Here it is, not all the way done with the 292 testing and you guys (and I ) want to do the same thing to a 250.

I have a few of them and fellow inliners do too.
Presently all the parts are ready and at the shop to do comparison testing
5 heads, stock, stock lump, 1.84 lump, 1.94 lump, high comp 1.94 lump
8 cams (Same used on 292)
2 intakes, OFFY VS Clifford
and some other things.

The dyno is also setup for this type engine. To dyno the 292 took lots of effort, money and supplies. Most of that would not have to be duplicated to do a 250. I am up for the task.
Need help with :
cost of dyno time
parts swaps
1 good shortblock

Strokersix has mentioned he has a good 230 and asked if I have 250 pistons.
I have 250 pistons. I will talk with him about getting a 250 lower end together.

Cost to dyno the 292 was in total 1800.00 and change . 400 of that being being supplies at the shop, like making and hooking up the exhaust, mounting engine ect. So true dyno time was around 1400.00. 4hrs fri, 9-8pm sat and 9-5 sunday. I expect the same for the 250.
So around 1500.00 should cover it.

Data collected would be fully shared with people who help support this dyno session. So if you donate atleast 20.00, you are in the full loop. Not all info will be put out on this site. Lets see how many are interested in this.

What do you guy's think? Tom

Tom:

I like the idea of more research and I'll send more money for 230/250 dyno time. I appreciate all your work, Tom.

JimRJ

Since I'm getting my 250 ready for my truck I'm very interested in this one for sure. I'd like to see if EFI-DIY would offer a TBI setup to try out???????????


Randy S. Hager
Venus, TX

Tom , I didn't get in last time. If your going again- I want in. You say go. I'LL chip in. 1 OL REDNECK

I am in again. Looking forward to the 250 results.

Rob

I'm in again. As I run a 250, I will be especially interested in your findings.
Al

Tom,
Of course, count me in same as on the 292.

Suggestion, if Strokersix has a stout 230 already offered, why not a 230 dyno session?

The 250 is right between 230 and 292 (or eh, 301) so would be easy to interpolate the extra 20cid from 230 to 250.

And from 230 it's not far down to 194 which some folks still have.

With the fewer inches, issues like too much port might come up on the 230 that were not a problem on the 301.

Either way, 230 or 250, I'm in.

Only thing I am not sure about is the 230 crank,,,does it have all 12 counter weights?

If not,,,it might like to vibrate a little too much @ the higher RPMs.

I have a 194 steel crank,( same stroke as 230 ), & it does not have 12 counter weights.

MBHD

I'd support a 250 dyno day as well. I suspect most late-model Inliners run the 250 anyway. The 292 is not an easy drop-in for cars, like the 250, for most enthusiasts.

My offer to borrow the Clifford 3X2, and Algon, manifolds stands for either engine for a high RPM test. The Clifford intake will need the carbs rebuilt and linkage made and the Algon setup will need everything but the intake, linkage, injectors etc. I don't have a pump or any of the accessories. Maybe some other Inliners can provide carbs or mechanical FI resources.

Talked with strokersix. He is willing to build a new shortblock 250. It will have a very good lower end with 6" Crower rods and custom aftermarket (light) pistons. I even have a lite weight GM crank that could be used.
It would be a flat top piston engine with Zero deck.

Chevy2inreno, the 3x2 and algon setup would cost valuable dyno time to get running properly. What we would be looking for is like with the 292, start with stock head / cam and work our way up. Just like most people do when building their ride.

I'd be willing to bet the 250 can match or surpass a simular built 292, mainly because it can rev better and that is where HP comes into the equation.

Hank, From the cranks I have seen, they are 12 counterweight. Only the earliest of engines got the 6 weight cranks.

Tom

I'm in. The two engines should be as much alike as possible so we can compare apples to apples. There will be enough information to keep us jawing for a long time. It is already evident that no matter what evidence is presented it won't convince everyone, but we knew that. Let us know when to send the dough. Beater

Even though the shorter stroke engines dont have near the harmonic problems a 292 has, the fully counterweighted cranks are better in dampening them, and are smoother running.

I'm in too.

If we can get 30 people in at 50 apiece or 50 people in at 30 apiece, that would hit the dyno cost target.

All the parts are on me as they are ready to go. The short block is Strokersix's. Labor on my part is free and anyone is welcome to come and help.
Will try to pick a date in early January to run it.

PM me if interested in supporting this and are shy to broadcast it.
Also feel free to email me tom@12bolt.com

This could be a very interesting test session. Tom

Beater - hmmm it would be easier shipping wise if your megasquirt was ready... no pesky customs people to deal with.

If anyone has three side draft webers & manifold to lend,,,that would be great,,,,,using that intake & carbs is AWESOME!!!!!!

Talk about torque increase!!!



MBHD

Testing a 250 as opposed to a 230 might give those thinking of building a 230 the incentive to step up and go with the extra cubes. Since the difference in the two engines is the stroke, it might offer more of a torque advantage than they realize. What to do about those interested in a 194 is hard to say. With the large selection in the different performance levels of heads being tested, im sure a head for all engine sizes is available for the 194-292 to suit the needs of everyone wanting to build a mild or wild engine combo.

Pesky customs people? Marc they keep us safe! No telling what would be shipped in here if they weren't looking out for us. (real beer) But one way or another I see I'll get no rest until I finish the Megasquirt. So I'll get back to work on it and if there's interest in it I could box it up. Beater (one of many Toms)

i've got 250 i'm about to put into my truck. i missed the 292 dyno, but i'll be in for this one. just let me know. will the block be bored? or did i miss that?

I'll send funds for the 250 dyno also, as I did for the 292 dyno. Personally, I'd like to see some other camshafts tested.

Comp Cams 260H (0.489 lift/212 0.050 duration) so often mentioned as a recommendation for the 250.
Isky 256 Supercam (0.492 lift/202 0.050 duration) or Schneider 256H (0.470 lift/204 0.050 duration) for those wanting a little more low end torgue.


Can exhaust systems be tested?
Original stock cast manifold.
292 cast manifold
Langdon cast headers
Clifford short tube headers
Long tube headers

Exhaust is a hard thing to test. It takes time and money to make the couplings/ pipes. The headers were relatively easy.

I am in for the cams, Can anybody supply those? Just from the #'s the comp 260H should be a good street choice. Even in a 292. Remember they need timing gears and thrust plates, I can also get, but they add additional cost.

Beater/EFI,
There are a couple problems with the TBI thing. First is the fuel system, this room is not setup yet for the fuel pressure needed or the return line. 2nd would eat valuable time to tune the TBI. 3rd there would be no real power gain over a carb. Once tuned, probably more torq.

Hank,
I agree, to test a weber setup would be great, who has one and also has what is needed to tune them?

I will also be in for the 250 dyno runs as I was for the 292 dyno runs. Just say when its a go and its in the mail.

Tom,
Me too. Count me in for fifty again, and remember, I've got that Comp Cams 268H w/ plate, wheel, & even lifters if you want to try it. wish I could swap it for 'new' Chevelle oil pickup tube..........had more interference problems so I/m out and opened up again. This time #3 has nearly rubbed a hole in the pipe.

Sorry to hear that , Joe. I remember when doing mine, had to really work on getting the clearance for the crank and rods.

There is one of the cams, Comp 268H

Who has a Comp 260H? Or the other 2 grinds? Tom

I'm in for this. I would vote for testing a 230, since I have one myself. It's also in between the 250 and 194.

In my case, I have a good running 230 with good compression and oil pressure so I will be doing bolt ons-head, intake, cam-before I do a complete rebuild.

Tom, we ran (3)sidedraft Webers on Cotton's engine for almost a whole season. Even though they had real sharp throttle response and excellent idle characteristics, and allowed us to set a few class and division records, the (3) Holley 2 bbls. we switched over to made almost 40 HP more.

I very much like Winter's suggestion of dyno testing exhaust systems if that is possible.

Maybe once the carb jetting is dialed in for the current headers, it might be ok to skip the sensors if that is making it hard to test exhaust systems. There might be some real surprises in comparing the various exhaust iron to exhaust headers.

Maybe even a test of the stock 1v carb and intake too?

Tom,

Re TBI

For a dyno pull the only real tuning required is idle, off idle tranisiton to WOT and WOT. The mid-range normally used for driving is not seen during a pull except for the off idle trasistion.

If the AFR from previous pulls on a carb were entered into the AFR target table and a wideband O2 sensor used to gather actual AFR data by logging the pull with the MS tuning interface you would only need 2-3 pulls to have a fully tuned system.

The tuning process involves data logging a pull, then use the fuel curve optimization s/w. Once the optimization application on the laptop is running then the datalog, and tuneup file for the logged run are opened. The tuneup file contains the fuel table, AFR target table and spark table.
Once opened the optimization anaylsis is run which will adjust the fuel table rich or lean based on the AFR target table and the datalog. The resulting fuel table is then loaded into the EFI controller and a confirmation dyno pull made with logging enabled.

Repeat the above process once and you have a fully tuned system. This whole process would take no more than 15 min's including the 2 dyno pulls.

Idle and off idle tuning does not have to be precise and can be done in 2-3 min's. If the AFR is a bit off at idle/off idle it doesn't matter.

As for the fuel system I think Beater has the complete tank/pump/lines ready to roll.

If it wasn't so difficult to get there from here I'd come down to handle the tuning.

I'm in again for $100.00, Talked to Tom Langdon (oredering more parts again) and he wants in too. He didn't know about the 292 until close to the date so he would like to get an advance notice of the date when it's decided.

Just a question,,,how would you think the 3 2 bbl Holley carbs & intake would work on the street?

What was the RPM range of that set-up?

MBHD

He does make a good point, I say that chuckling.

We are aiming at street engines.

Jalopy, I will see if Tom can lone a set of the cast headers for dyno use. We did find the EGT never got high, so no need to add the temp bungs. Still would need to bend up pipes.

EFI,
I am still not sold on trying a TBI. And you know EFI is nothing new to me. EFI is awesome for tuning. It would be alot more work and not sure if anything would be proved. It is proven on many Vthings how much power they can support.

Well they are only available in 350 CFM as the smallest, so even(3) of them would probably be to big for most street 6's. However, a lot of the older vintage hotrodders use the small Rochester 2 bbls. with 2 or 3 carbs on inlines, so maybe that could be a possibility for a multi-carb setup that would be streetable and not to much CFM. They were like the old tri-power GTO's back in the 60's. I forgot also, that the Webers will fit under the hoods of most cars since their side draft, the Holley's will make you have to cut a hole in the hood and use a hood scoop in some cars.

What was the RPM range for that 3 2 bbl set-up?


MBHD

In the Comp rear engine dragster, it was launched at around 5000 RPM and shifted at 7200.

Tom

I think you will pick up power from better fuel control. That said you can only lead a horse to water.....

The EFI is just too much of a pain to do. There are many more important things that need to be swapped and checked. A glick with a EFI unit could cost a 1/2 day. That I am not willing to sacrifice.
I run EFI on my car and know it is the cats meow for tuning, just not willing to do it on a motor that is designated to test parts and theories.

By the way, what do you do with that horse once you lead him to water?

You let him stand there an figure it out himself. duh. lmao

I prefer my horses under the hood.

On the 3-2v setups:

They may not be too big although admittedly they take a lot of tuning. As you probably know, the 2v carbs' CFM are rated at 3.0" Hg, whereas 4v CFM are (usually) rated at 1.5" Hg. So, a trio of 350cfm Holleys, if rated by the 4v rating, does not flow 3*350=1050cfm, but rather about 750cfm total.

It can get even better:
The smallest 2300 Holley 2v I've found is not the "350" (about 250cfm using 4v rating) but rather the 1-1/16" venturi Holley which I rate at about "265" cfm, or 190cfm on the 4v rating. Three of these carbs would give 570cfm with the 4v rating which is just about the size Tom used on the 292 tests. Not so bad.
I have one of these carbs, it is List 2463, a factory AMC application. These small 2300's dont exactly grow on trees but they are around.

As you said, the little Rochesters are similar. The 283-2v carbs are pretty common and were about "278" cfm (2v rating) or 184cfm on the 4v rating. So a trio of them is only 552cfm.

With three of either the smallest Holley 2300s or the small Rochester 2g carbs the 250 dyno engine should be happy enough, but they are still time consuming to set up unless somebody has already dialed a setup in on their own street engine.

I'm glad the 250 dyno will give us a "Part 2", so much data will come out of this even if Tom can't do all the ideas.

One of our local guys runs 3 Webbers on his 292. I'll talk to him at our meeting Saturday. Maybe the shot at fame would get him to switch for a while. Probably get some of the members to kick in beer and help with the switch. It'll be tough!

Tom:

I have another check headed your way (via snail mail) today. Use it to finish up the 292 pulls or on this next project as you see fit.

I know this would NOT be a possible 250 configuration to test but the results (or lack of them) would sure be interesting:

Suppose you take the best 250 combination you achieve in your future dyno pulls and simply moved all the components over to the 292 tall deck block with the only change being a switch to the necessarily long (7.425" cc ? - yikes!) connecting rod to arrive back at a zero deck. I'd be very curious to see imperical dyno proof of the benefits (if there are actually any at all) of a long rod configuration and its significant improvement of the rod:stroke ratio.

If I did the math correctly, the resulting ratio would go from 1.6:1 for the 250 block to something like 2.1:1 for the 292 block - all other things remaining equal.

It may be that the better rod ratio will only show an increase in performance in a maximum effort race engine and show no measureable impact at all on a street motor. And even if there were a positive impact, is it even remotely worth what the cost of the custom rods (and perhaps piston package) would be? Probably not but it would be interesting to know for sure . . .

Russ

Thankyou Russk,

The dyno charges as of now were more than what I recieved from you guy's by abit.
Total recieved was an amazing 1405.00 from about 30 of you! So the charges are off by about 400.00. I am ok with that.

There is more running to be done yet and hope to get more clean runs this weekend.

Guy's the multicarb thing is a tough one. The only way I'd be interested in doing it is if someone had a good running setup to try. It would take alot of time for me to set one up (jetting and such). Tom

I have stated before ,,I ran 3 48 MM side draft weber DCOE's w/something around 46 MM choke tubes,(not much smaller than the throttle valves.

The carbs were too big for my 250,,,but,,, with those carbs,,that were even too big,,,made more power,,,more torque,,,better streetability than any 2 bbl ,4 bbl, clifford or offy intake combo I ever tried,,,& believe me I tried almost all popular carb combos & even not so popular carbs,(thermoquad)example) with both the clifford & offy intakes.

I just wish I started off with the Webers first thing,,I would have won a lot more races w/those ;-)

I think the 3 48MM webers flowed about 1100 SCFM.

It seems w/Webers,,,it's kinda hard to over carb.


MBHD

Hank, was there a ballance tube on your Webber setup, or was it like 'normal' Webbers? (ie, no ballance tube)

Nexxussian,,


no balance tube,,I had the Clifford/Weber intake.

With Webers,,I think it is as close as you will get to fuel injection & still be carburated.


MBHD

Here's Steve's Webbers. Webbers

This may be an area where Tom Langdon could help???? He's done enough of them by now he should have the jetting etc. pretty well base lined. Multi Webers are a nice carb but not as affordable for most of us as a standard Offy with 3 carbs. Now if we ever go for a race engine dyno test they should be included along with some big carb and mechanical fuel injection setups. My 1 cent.

Looks like we're headed for a third set of tests using the best set up from these and a bunch of carbs and injectors. Then there's the whole boost thing. Tom what are you doing for the next couple of years? Did you say your wife used the word "crazy"? I feel the best information to be gained in the 250 tests is to repeat the 292 tests as closely as possible. After all we don;t want to answer all the questions in the first episode. You've got to leave room for a sequel or two. Didn't you guys read Harry Potter? I see a trilogy in our future.:D Beater

Well, before we spend too much more dough, we could almost buy a dyno for what we will end up spending for several more dyno sessions....then you could test virtually any combo imagineable with only time being the main contribution to deal with.

I like that idea CNC. Dyno connections (harness, hoses, stands, etc.) all set up for inlines. No rush to get out of the way either.

Xactly, sometimes you just have to see if the end justifies the means, before you realize you could have bought one for what you payed someone else to do....just thinking ahead. Seems like this can be an ongoing R&D project for these engines, so why not!

Lets buy one and set it up at Tom's house. Then we could all use it when we want and Tom could help us. Oh yea, his family, well we could put it at my house. No help though. I think there's a chassis dyno around here that could be had for cheap. Beater

Tom, check your paypal, now to interject some probable faulty logic, if the Clifford produced more torque and hp across the board on the 292 if the same occours on the first few 250 tests do you need to change manifolds for each cam and/or head change on the next pulls? Trying to save you some labor and maybe free up some time for other tests.

I am interested in this effort and may contribute. I haven't been watching the 292 thread that closely, so I'd have to figure out what the plan is. I'm interested in the 260H cam since that's what I'm using and also the lump types and intake/exhaust options.

If we are trying to trade off different heads and cams for primarily street engines, why start with a relatively exotic short block with high end internals? Couldn't you do all the same with something closer to stock?

67pete,
We are testing this engine and the 292 for street driven/ proven combo's. Each cam, intake, head is tested. Idle vac readings are taken and pulls start at 2500 rpm and go till the hp falls off.

A stock built lower end would do the job. But repeatability is what is desired. After the dust settles, There would certainly be a home for the motor.
For the 250 build, the components would be setup for longevity. Crank/ rods/pistons balanced. Forged pistons, crower rods (have them).
With the time/labor invested, all would be wasted if the base of the test mule started to decline during running of all the pulls.

I am all for a test of the Comp series of cams for the 250. Can someone get them to donate them? I have tried and got no help. Tom

Tom, i've gotten Comp to contribute to several of my engine building tech articles in the past, i'll give my contact there a shout this week and bring him up to speed so far on what we have done with the 292. They have been pretty easy to get contributions from in the past, at least for me, so if you can get me some specific part #'s before I contact him, that will help me know how to proceed.

Guys, my 250 originally came with a .600 lift cam that I removed because it wasn't streetable. Appears to be barely broken in but I didn't see any markings or numbers so I don't really know what it is. I supposed it can be measured.

At any rate, if you want to add it to the mix, I'll be glad to donate it to the cause.

Tom, I have the CompCam 260 in mine along with the head you did... Alum pistons, 60 over. Offy intake, Clifford truck headers, Edelbrock 500. Is that close to one of the configurations in the plan?

Kerry, i'd say that combo is spot on for the components we have available, except for the camshaft. Tom sent me a list this morning of the Comp cams he would like me to try and get from them, the 260H being one of them. I'll make a call and see what shakes loose.

I'm not opposed to pulling my Edelbrock and loaning it for the test but it is on my car and I'd a short turnaround. Don't know the issue with shipping a gas smelling carb these days either.

Tom;
Money order is in the mail.
Thanks, Al #4802

Al, james, Jalopy, and others,
Thankyou again for your help. Glad to see the support!

Kerry,
I do have a Edelbrock 500 and 600 sitting here. Why don't you bring that roadster up and we will have some fun!

I am presently getting the pieces together to form up the 250 lower end. Try to pick a date in January. We will see what happens.

Tom

I wouldn't be surprised if you get a ride one of these days Tom.

Tom, on the 292 thread you mention that you're pushing the 292 to 5400 RPM and that's into the concern range.

Of course with all the problems and crap with my 250 I'm not sure what to believe but the guy I bought it from said that the builder said his engines (built for the Nascar dirt track series in VA) would turn 6000 all day.

I doubt that my engine will ever see close to 5000 but just wondering...given the shorter stroke, what is the RPM range for a flat top alum piston, small block rods, balanced 250?

I turn my 250 to 7000-7500 rpm ,w/supercharger. . flat tops w/stock rods.

If you have a good damper on the crankshaft,,,they will turn higher rpms.

My 250 engines would never want to go over 5500 with a stock damper.


MBHD

Hank, what's the failure mode associated with "would never want to go over 5500 with a stock damper"? Damper explodes, crank breaks, pistons self destruct, or?

No failure,,,it just would get so much harmonics going on you would be loosing power,,,you could go higher RPM,but would not get anymore HP by doing so.

Switching to a good damper would allow you to go higher RPM & actually make more power.

My engines were all balanced pistons & rods weighed exactly all the same.
Zero balance the crank assy's.

MBHD

I think unable to reach performance potential due to harmonics qualifies as a failure mode.

I do not see it that way,I'm thinking failure = broke something,,I changed the damper & then would go to 7500 RPM.Which reached beyond my performance expected,AKA potential.
But,,,to each his own.


It was a learning process,,no company tells you straight out,,,,,if you want to rev your inline over 5500,,,you must get a different damper,,,that was back when I used to talk to Jack Clifford for advise, & I must say,,,most advise I got from him & his staff was pretty bogus. IMO




MBHD

Kerry,
To answer your question. 6000 is a safe rpm for a 250 if built correct. They will go much higher in RPM but those are different engines than we run. The valve springs you have will also allow you 6K rpm. Tom

hello! i lurk on here from time to time but dont do much posting. But this seems like such a good cause I'm in too. I just sent some money via paypal. im interested especially because this fits in with my 63 nova. it currently has a 230 with clifford 270h cam, intake, and headers. It has the 390 holley and a head that i ported myself and shaped the intake boss into a wing with 1.94 valves. I have a 250 sitting in the garage so this will be great for a possible build down the road. Keep up the good work this is great stuff!

I ran a 57 Chevy 283 "270 hp" in Junior Stock back in the 60s. We were allowed 55 lbs. on the valve seats and I saw 7200 rpms every run. Of course that was a solid lifter cam and the springs would fall off real bad after 10 to 15 runs. I run 90 lbs.on the seats,194/160 valves, opened up pockets,NO LUMPS,zero deck,flat top pistons and 262/ 500 lift cam by Lanati in my 250 and like you say 6000 is no problem..but from 5000 on it just stops pulling hard. As some one on this board said "not too much cam..Just not enough motor".. The balancer issue is something I need to look into more... J

Ok guy's,
Pulling a greasy 250 down and going to document the build on it. This will be the 250 for the dyno tests.
It will be fully balanced with:
Custom pistons (flat tops)
Crower Billet rods (allready have them)
zero decked
Allign honed mains
Find out overbore after teardown, try to keep to a minumum. This lower end will be reved to a higher rpm on the dyno for testing.

Thanks for the contributions so far on this 250. Tom

Hey Tom:

I have a lot of other things right now pulling money out of the wallet but if the dyno run is not until Feb I'll send you some money. I'm getting the garage cleaned out so I can get my 250 built up too. First up.....balance rods and pistons.(cast flat tops) Box says that they are weight matched but,"I'll be the judge of that"! I will be keeping an eye on this thread!

Randy S. Hager
Venus, TX
Still designing the Berta type head!

Yeah, I think the 292 dyno testing came a little quickly for some that wanted to participate, but couldn't, because it did happen on short notice. Tom and I both wanted to test a new Hydraulic roller cam conversion on the 292 that I have developed, so maybe we can test it on the 250. I also have designed and prototyped some exhaust port plates for these heads as well that we didn't get a good chance to give a thorough shakedown either, but so far they look very promising. So there is still several new products being developed for these engines that hopefully will have a little more time to tweak and perfect this time around. So it just isn't existing products being tested, its also new technology being developed as well.

I was getting curious about the status of your Berta head project.

CNC-Dude:

Very interested to see how your hydraulic roller cam works out, as well as your exhaust port plates. Sure would like to see some photos of each when you have the time.

I'm also curious about the Berta head project. I think you suggested some reshaping of the ports to improve (lower RPM) velocity might be worth looking at. In any event, if a new aluminum version of this head were to come to market at a price point similar to the CI small Ford head, I can't imagine that it wouldn't be purchased in significant enough numbers to be profitable.

Russ

Russ, the exhaust port plates was something I threw at Tom in the last days of testing. He was already overwhelmed with combos we had pre-planned to test, so naturally, we weren't able to evaluate them to their fullest potential. But right off the bat, I saw several changes that needed to be made immediately with the initial design, so that will give me an opportunity to rectify them, and then test them further. Also, since you have interests in the Ford 300's, im already seeing crossover potential for these plates with that engine as well, so don't worry, im already thinking way ahead.

Clyde @ PES Made these same plates years ago.CNC dude is not the only one working on these.When clude first did these plates they were not ment to be bolted in. As He told me many yrs back.

Mine are designed similar to others that companies that also make them that require no welding at all. I have never seen the style that PES makes, so I can't say what is required to be able to use their brand. But like Larry mentioned, I have also heard they require welding for installation, so making a version that will allow them to be installed without welding, or even any machine work, as mine are, is going to increase the marketing potential, I think, because of the greater ease in which they can be installed by the end user. Also, patent protection will also be an added feature incorporated into mine, so before this product will be revealed, that will be in place first.

CNC-Dude:

The Berta head will take some time to get through the design phase. I have hand drawn some port sketches but still need to have them done with CAD and check it out in 3D. One of the design issues is that I want 360 degree water flow around the exhaust ports and I'm having a mental block about it. I hate getting old. I'm only half century old. I would like to check out your roller cam for my 250. Do you think that a profile similar to the 262 V6 would work for an inline engine? I'm only looking for max torque and I'm running a 4L60/700R4 trans and 3:73 gears with 28.7 tall rear tires. Well......as soon as I get it all together that is!

Tom; A C-note will be in tomorrows mail. Hurry! Wish I could afford more. (I do know how to pronounce Lowe)
SOB

After going over the the dyno sheets for the 292 I have a question for the 250 test and that is will it be necessary to run as many head and cam changes on the 250? After the baseline test, if the Offy intake with cam 2 and Clifford with cam 2 are run and say cam 3 w/Offy and then the Clifford and the numerical spread in the readings is like or close to the 292 we should be able to mathematically predict at least the intake hp gains for the other cams without swapping intakes? I would still like to see a multicarb setup tested to see if the spreading out of the fuel charge has any significance. Any possible date yet for the 250 dyno pulls??

I know this isn't much of a concern for some looking for all out power, but is there a way to test fuel consumption?

Based on a stock head vs a lumped head, etc. Say, x-amount of fuel and record how long the motor will run on it? Giving us a comparitive look at how headwork can effect all aspects of an engine?

Just a random idea that might be fun to play with, since it's a controlled test environment. ALthough it might not be very cost effective.

-Sam.

That can be figured out using the FuelMass(lb/hr) readings and the EGT (exhaust gas tempertures) to give you a good idea of fuel effiency. These dyno runs were for a street engine combination and not for an all out comp engine. When Tom get the rest of the stuff out of the way you can probably read the results in the 12 Port News.

Ahh, ok. I kinda figured there'd be a better way than a crude x-amount of fuel in y-minutes, kinda thing.

And since it was/is a street test, maybe it's of more importance than I initially thought.

And Tom, please let us know a set date, etc. And when you'd like contributions in by.

-Sam.

Jalopy,
I am working on getting a 3 weber side draft setup to test with. Hope that helps.
You are correct , not as many head/ cam swaps will need to be done. Still would probably test about 6 cams. It is good to see what works and at what ranges it works.

Sam,
The BSFC#'s are exactly what you need. They show how efficient the engine is operating, atleast for us @ wide open throttle.
The lower the #, the more more efficient the engine.

No date is picked yet, Going to get started with the lower end after the new year, glad the 292 was done before the Christmas rush! Tom
Tom

You will be impressed if you can run the Webers.

What size 45 MM's?


MBHD

Not sure, will find out at a later date. This is just being hopefull. Tom

I've been thinking of one of the brazil intakes for 3x2bbls. The sidedraft webers work great as long as they're kept tuned, but because of the individual runner design, if one carb goes sour you lose 1/3 of your power.. I think our freind from FL sells these on ebay but Ive never seen one sell yet so I havce no idea of his price. http://www.engineracing.com.br/coletor%2...aquecimento.htm

The 3X2 ,2bbls should work pretty good.

The only problem I had when running 3 DCOEs of comming out of tune was just the carbs being out of sync,just a couple minutes w/a motorcycle carbs stick (mercury stick) hooked up & easy adjustment.

Even when they did come out of adjustment,it would be easy to feel the roughness & idle & when slowly excellerating,,,W.O.T. could not tell the difference if they were out of sync.

Changing jets ,emulsion tubes etc, have got to be the most simple things to do on DCOE's(Sidedraft Webers) ,no draining of the float bowls, reuse top gasket,etc,simple ,simple ,simple.

MBHD

Jalopy, the intake manifold in this link is roughly $325 USD + the shipping and duties. Tom already has an intake from another vendor lined up for the dyno testing with the Webers. There just isn't an inexpensive way to buy that stuff from Brazil, because the duties and shipping that someone has to pay to get it here in the US are going to have those costs factored into the resale price of the item when you buy it from them, plus whatever markup for profit they also add to it to stick you with.

Yep, they ream you to ship & import/export to the US & Brazil.

I bought my SPA turbo manifold for $120 US ,but we had a friend that would fly to the US & have it as carry on luggage.


MBHD

That sounds like the best deal you could ever ask for there. Knowing someone that is going there would be awesome to get a carry-on item like that on the plane.

I picked up a 292 exhaust manifold last year in Idaho. I went to a garage sale and for $2.00 got a old suitcase. Packed it in foam rubber and checked it as luggage and boarded plane. Picked up after flight with no problem. Days later opened suitcase to find they had opened and checked. There was a printed note inside telling me they had checked. I can just imagine this day and time if you carried that thing through the air port that it would throw those folks into a tizzy, especially being on a international flight !!

When they look or check the manifold,you just state,you are bringing it for repair. Same for cylinder heads etc.

Carry on on luggage not check in luggage.


MBHD

Was not trying to doubt what you were saying ...Just never thought about claiming what you had in hand. Now I remember a guy flying back from Alaska with his finger in a ice cooler.... coming back to the lower states to have it reattached.

Was not trying to doubt what you were saying ...Just never thought about claiming what you had in hand. Now I remember a guy flying back from Alaska with his finger in a ice cooler.... coming back to the lower states to have it reattached.

Last year my son flew from Texas to California with almost a full Harley front end, including the wheel, in pieces as a carry on. The only question was, "What is that?" We have carried a lot of parts on plains but don't ever try it with a tool. They don't like that. Beater

I am an A/C mechanic along w/co-workers that fly the airlines sometimes to go fix A/C ,they go through w/there carry on bags w/tools all the time.


MBHD

It's kind of an interesting situation. This is probably how everyone else feels when they need stuff from america.

Trying to get my brother who goes to Uraguay a few times a year to bring one back in his carry on luggage, Would like the complete engine from there.

Hank, it all depends on what tools, they get downright pissy about screwdrivers and gasket scrapers.

Of course if you can jumpseat on your own airline it helps, alot. I guess they figure if you already know where the crash axe is stowed the other implements aren't too critical.



Yeah, I sould love to be able to bring some of that kind of stuff from the countries I could get them from for a few projects I have. But then I'd have to be able to afford the part, the import duties, AND airfare. (dang)

Lets get back to the 250 Dyno info!

Here is a thought for the next 250 dyno.

Tom can use some intake port dividers for the 250 dyno session.

I noticed his statement about how good his intake port dividers makes more power w/no dyno proof.
Track proof is not reliable as was pointed out earlier. Tire pressures being different, temps of the day, alititude,standard degree day & so-on.You had an off day.

I have no doubt that w/his deviders installed ,the idle improved,better throttle response,why,? increased air velocity through the intake port.
Would probably get simular,(not as much) results by using the offy intake manifold instead of the Clifford he is currently using.

By deviding the intake port & making the intake port window so small,you could possibly see an increase in your low end power,but in the upstairs dept of higher RPM,it will make less power,the head can't breath w/that type of devider.

When you install intake port deviders it will severely cut the flow CFM wise to the intake ports,not just by a little ,,by a lot.

Now w/Tom posting w/the 194 cyl head is down flow about 20 or so CFM as compared to the open chamber head,thus making less power, would'nt you think this can be or could be a posible contradiction?

How can you can more power if you loose CFM flow of you cylinder head? His dyno session of the 194 cyl head proved it made less power everywhere, the 194 head was down in flow.


Turbo 6 has already proved this idea is false w/dynoing.

He had used intake port deviders as to make sure all the cylinders were getting close to the same amounts of fuel.

With the intake port deviders,his power was down on the dyno,so he had to up the boost pressure to make equivelent HP w/no deviders.

W/the deviders installed, the intake port window has become too small to flow good. It is a restriction.BIG TIME!

That being said,,when you are forcing air/fuel into a poorly designed intake port such as our siamesed ports,, design is not as affected/critical as in a N/A engine.

Tom,
dont take this personal,,just thinking about what other items you could add to the dyno session.

And as far as every car nut wants to be different,well some people like recipe combos. Such as getting info from Toms dyno session.
Proven parts for a no hassle install.

Some guys just would like to go to a store & purchase recipe/combo & not have to think about it.

So car nuts are all different,that's all.

MBHD

We have discussed doing it. And it would be interesting to see if there is anything to it. But also remember Hank, that you are thinking of putting a port divider into a stock sized port. And your right, you will reduce the port window significantly, and might not even get much gain above a certain point. If you go to Glen Self's website, you will see how a Comp Eliminator size port looks, and that divding a port that is that large, such as my friend Darren did, wont be the same as dividing a stock size port. A race intake port is over 1-5/8" tall by 2-5/8" wide, so opening up the port opening to compensate for the divider will have to be done, or your correct, you will probably have no benefit from dividing it. The whole lump port vs. the divided port is going to require a completely different approach one to the other, and trying to adapt or use previous thinking from a lump port perspective, and applying it to the divided port concept might not show any advantage when done that way. I don't think it is going to be as easy as just putting a divider in the stock size port, and voila, you have a giant increase. You are going to have to open up the port to obviously regain some port area that was lost from putting the divder in place to start with, so that is where the R&D starts.

Hank,
I will probably test divided ports with the 250, am working on that now.
Remember with my turbo 292 and dividers. They helped me because of the Multiport EFI, it was a scavenging problem between opposing cylinders not a flow problem.

The head, being worked up has much widened intake to manifold port and the height is also increased. Now just need to make a nice divider. Tom

Tom,
The deviders also helped w/Turbo 6's carbed engine,so it's not just a multi port thing..

Now that you have installed your deviders,you may have helped the scavenging problem you have now a flow problem now & it's limiting your potential HP & torque,AKA ,,flow problem. It's just not as apparent w/the turbo stuffing the air in your cylinders.

The only way the deviders work (by flowing OK)is when you make the intake port so huge, it's not practical for a street car. I have done this about 20 years ago.
Quote:"This is not what the average Guy will want to do for a street engine"

Goodluck on you quest!

MBHD

Scott -
I've been trying to get in touch with Darren Davis to talk about his work to the lump port head. The last number I had for him was at the header shop. Could you please give me an up-dated contact number?

Also, I did learn some interesting information from Sherman.

Thanks,
Bob

I don't think I have any current info on Darren either.

Is leelites sending one of his prepped 350 + CFM heads to Tom for dyno testing ?

Just thought I'd ask.


MBHD

Yep!

Great , I hope Tom will flow that head as well.

MBHD

I think Lee is doing it before he sends it. I think its cool he is wanting to participate, even though he isn't a member any longer.

Well ,at any rate ,the dyno test of his head will make or break him.

For his sake & rep, it better be outstanding.

We shall see.

My friend had already proved him wrong about the siamessed port & his views & thoughts.

Maybe, he can pull a rabbit out of a hat.

He still keeps bashing people on the BB,hes lucky Tom has a sense of humor or ? & would even consider using a cyl head from him.
He should be very thankfull for the upcomming opportunity to prove his theorys.
His cyl head better flow 330 + cfm as he tried to sell me one of his 350 + cfm heads through a private PM, but could not give me a price.

MBHD

You can tell by his recent auction, that he has toned his comments down quite a bit on there, and has even spoken to Larry recently as he mentioned. So, I think he has finally set aside his emotions and differences, and made peace with those he has had hard feelings with and moved on. And he seems to be comfortable with letting Tom test his head without feeling he will be biased against it one way or the other, and fairly evaluate it without prejudice. And is ready to accept the results whatever they might be.

Ebay has been deleteing his auctions & have been warning him about his auctions, he is forced to calm down, otherwise he cannot sell anything on Ebay.

Have not seen his recent auctions.

MBHD

I thought you might have seen it, and thats why you mentioned if he was giving Tom a cylinder head to test.

Lee did not say this head flows 350 cfm. But I believe he is supplying a flow test, or atleast I hope so.
Told him I would go thru the head to be sure parts are upto snuff, hate to see a loose keeper ruin the engine. He was ok with that. He is setting it up for the cams specs I gave him.

Maybe Larry or Hank could provide and worked up "194" head and show how they can be made to work. I would really like to see one work good.

Got a 3 weber(type) side draft carb setup coming. From 1/2 way around the world! How is that for support!

Thanks for all the contributions, just finished paying for the 292 dyno this weekend. The 250 will be more out of immediate pocket because of the shortblock build. It is for a good cause and glad I am able to offer up the service. Tom

Just curious how many hrs where used for the dyno session, Rate per hr?

I for one do not have any spare time to work on anything, let alone work up a cylinder head,,between work & kids & wife having different work schedule. It's nuts!

Right now ,I am baby sitting the whole day on my days off while the wife works.

The little one is throwing up all over the place,,,nuts, I tell you nuts.

MBHD

Delete.

Scott, your pal Tom asked me to remove them. So I did.
Tom does not like him & Tom does not call him for advise,which is a wise choice.

You should listen to both sides of the story before reacting.

Look @ what you buddy posts on ebay, he sure is the real deal.
A real work.

I think you owe me an appology.
He is giving you stuff in hopes to find someone that will listen to him. & you fell for it.

I believe Mike Kirby has stated you can believe in Leelites as much as you can trust Joe Deppe.
I'm done.

http://cgi.ebay.com/ebaymotors/Chevy-Inl...sQ5fAccessories

I removed my post as well, as per Tom's request.

Now lets all move on back to the discussion at hand.

Just curious Hank, did you personally ever deal with Leelites?

Ok
First off I said I was done here as to posting. Now I am going to
OPEN my Mouth once again. So first off I never called Lee secondly I listen to what He was saying I never said Much of anything. THEN I see His Normal BS on Ebay Saying I said this ot that which to is BS The Guy always talks in circles Or changes the questions around when he is asked one. and still ONE never gets the answer they asked and That I still see. If I or others are doing things so wrong.Then what the H*ll is the problem giveing the right answer/s when asked. So to me Personal Oppion here it's still the sameOle bag Of crap.
He takes what anyone has to say and turns it around an then out comes the BS.

And Scott so as to him speaking to me (and has even spoken to Larry several times in the last few weeks,) That is a Load of BS
I maybe spoke with him once in the past MO.ANd I let him do all the talking i never said much of anything.
So take what ever you want to hear they way you think it is.I know not everyone is in or was in the Lime light of things like sone think they may have been.
Now you all have a Great day and Injoy your chats.

PS if anyone wishs or see this as a Bashing Then so be it. It's the way you maybe reading it.
It's MY 2cent an once agian I'm done.

No, I choose not to get a headache, but my friend has &,,,,,,,,, coo-coo.

So, Tom, I heard a while back that you were planning on doing some dyno tests on a 250. Is that still going on? Are you looking for donations? It's hard to find much about it here. Beater

Yep, the tests will be going on. This weather has slowed me down. Had to clear my shop to get the F450 4X4 flatbed in there. Talk about leaving the freezer door open. That truck has a winters worth of ice and snow stuck to it, and winter is only about 2 weeks old! It took over 24 hrs to thaw it out. Now to change the fuel pump.

Next the 250 will go in the shop and be dismembered for rebuild. Only the one divided head to work on also. The rest of the parts are still ready from the 292 dyno tests.

Contributions are coming in. Got one from SOB, Bill Mulholland from down in Texas, sounds like they are also getting a taste of winter (not liking it much either).

If anyone is interested in helping, here is the wish list.
Possibly 3 cams from Compcams
3 cam timing gears from cloyes
funds to help pay for dyno time

If anyone wants contribute funds, here are the 2 ways

Paypal to tom@12bolt.com
(send it as a gift and they don't seem to take out fees)

or by mail

Tom Lowe
3063 200th st
Dysart, Iowa 52224

Telephone 319 476 2172 evenings 6-10 pm

Anyone who contributes get the data collected from the tests. For the 292 dyno tests, over 50 contributors helped make it happen. Some from far away in other countries. Contributors are also kept confidential. I do have a 250 dyno list of contributors started. Thanks again to those who have allready.

Now out to change that fuel pump. Tom


Fuel pump is done now, fuel at 50 psi really helps make that diesel roar.

Tom -
Just wondering how your magazine article was progressing. Will it run before the 250 tests or will you wait until after they are done?

Bob

I'm going to call Al Gore and find out where all that Global Warming is going on and move there. It snowed here a week or so before Christmas and I got stuck on my way home from work New Years Eve. My first act of the new year was to walk back down with a set of chains and a shovel New Years morning and get the Yukon, 1/4 mile from home. The snow is mostly off the road today but we are getting more tomorrow. I've just got to get the dozer fixed and cut more wood in the summer. Sorry to whine I'm sure efi-diy is really cold. I'll send $$$. Beater

Bob,
The article is going good, most of that is in Scott's hands now. He is a much better writer than I.

Doubt it will be in a mag before Dynoing the 250. From reading articles in many mags, they seem to be about 3-4 months slow. Tom

Tom,
What size & brand side draft carbs are you going to use?

Do you have any 194 heads flow tested w/a 1.85 -1.90" range intake valves installed?

Would it be possible to test a cyl head w/these size valves for the dyno runs & have the head milled a bit more (than the previous 194 head) for more compression?

MBHD

Do not know the brand, they are just not a familiar carb to me. Believe they are 45 mm.

As far as the 194 head. Not going to build any with small valves. The 1.84 valve in that head will not flow as well as a 1.84 in a open chamber head. Will rerun the one run on the 292. May open the chambers some. To match a open chamber heads clearance, might as well started with a open chamber head.

I personally think there is more power to be had with different techniques than a "194" head. Which has also been proven to me with flow tests and dyno.

Still open to someone supplying a prepped "194"head. Tom

The 250 is definately started now. The boy and I tore down the donor 250 today and took it in to be hot tanked. Next the machine work will start. The motor was a 76' 250 with a 1bbl integrated head. The head is in the iron pile now. It had to be as heavy as the block!

Recieved the 3 weber side draft on Friday. Carbs are also coming.

A few more contributions have came in and thankyou's to you guy's.

Taking pictures as we go on the teardown and build. Tom

Tom are we looking at Feb. or March for the next tests?? If we wait too long will the dyno costs go up?

Jalopy,
Not sure on a date yet. Just yesterday( Fri) the block was hot tanked and magnafluxed. That all looks good. Preliminary checks indicate a .040 overbore. Block will be decked and bored next week, then order the pistons. Crank will need to be turned and balanced. The dyno has a Pontiac on it now. The operator was teasing me and said when running the Pontiac, the dyno popped up a message stating to test only 1 inline 6 at a time as the torq reading was too high. The Pont is a big cube sucker and was pegging the tq beyond the 500 ft pd mark closer to 600 ft pnds.

The lower end should go together relatively fast. The top end stuff is still ready from the 292 tests. Still aiming for later feb. Anyone interested in coming here to help? I know my local club will. Maybe some of you guy's could come too. Tom

Pistons ordered today, block did bore to .040. Deck height measured 9.135 so ordered pistons for a zero deck and pure flat tops. Crank was deburred and going into the grinder on Fri. Tom

Tom, Exactly where is the measurement taken for the deck height? Crank pin center at TDC to top of deck? Beater

Recieved the OER/Weber carbs and extra parts from 1/2 way around the world! He also sent a new side draft intake. Now that is stepping up to help out with the 250 dyno tests. Will be interesting to see how it runs with this setup compared to the normal parts.
Pistons should be here in a 1 1/2 weeks. Tom

You are going to ask yourself,why didn't I buy & run side drafts years ago,instead of this dumb 4 barrel carb & intake manifold.

It will impress you if there jetted correctly.

As always,how bout some pics?


MBHD

One reason not to run the weber type carbs. No choke. Would not work well in my climate. He sent the carbs with 40mm chokes? (venturis). Also 36mm and 32mm.


Got the crank back. It is turned .010/.010. I deburred it before taking it in, oil holes are all chamfered now. Really looks nice!
Cam, rod and main bearings are all ordered. Crank is getting balanced next. Got the new oil pump, will disassemble and deburr it.

Block work includes:
Plugging the oil bypass (like full oil filtration all the time), plug the front timing gear oil spout.
Deburr the internal block.
Chamfer the cylinders near the intake/ exh valves ( better flow).

Get a couple more cams ready with timing gears.

When pistons get here, get rods/ pistons balanced up.

Winter is going fast if I keep this up. Tom

Some Webers have a cold start circuit (choke), others don't, it is very easy to flood the engine and wet plugs using the cold start mechanism, as it very crude in operation. The accepted technique for cold starting is as follows:-

Allow the float chambers to fill if you have an electric pump, this should take about 5-10 seconds, fully depress the accelerator rapidly four times, then on a light throttle, turn the engine over, if it does not start immediately, repeat the procedure three times. The engine should fire, but may need 'nursing' for a minute or two before it will idle, gentle prodding of the accelerator should keep it alive long enough for it to warm up. If the engine does not fire within three attempts, then try five or six pumps. If this does not work, depress the accelerator fully and hold it open while turning the engine over for 5 to 15 seconds, then close the accelerator and try again.

A different guys quote:
And cold starts are no problem since they have an accellerator pump and a cold start ... My Alfa with webers started easily in zero deg weather. ... That aside, a properly tuned IR set-up using Weber DCOE, IDA, ...

On difficult to start engines with carburetors, waiting 20 to 30 seconds after pumping the accelerator pedal several times before starting also helps. This allows some time for the gasoline to evaporate in the manifold. This technique works well on the second or third try if necessary, but does require patience.

I'll ask my friend Steve how he got his truck started to get to our chapter meeting tomorrow. He's bee running 3 Webbers for many years. Beater

This is where I came in.

Enough about the choke. This engine will start just fine in a controlled dyno cell enviroment.

More interested in power output. Tom

Tom, I thought my 68 250 block already was full flow filterd! also why the timing gear oil blockoff. Herb 3241

Herb,
These series of engines are full flow filtered. But at startup, with thick oil viscousity, there is a bypass that can and will open. This will allow unfiltered oil to bypass the filter. GM put this in so that when dummy's did not change their oil and the filter became plugged, the motor would still have oil pressure.

I plug the front oil spout to keep more oil for the crank/ rods. Later Gm engines did not use this feature. Plenty of oil flying around down there. Tom

I see that Leo's book states that for street use,, eliminating the oil director to the gears is fine.

But,,what about for race/street double duty cars?

Anyone?


MBHD

We always removed and plugged all of ours, as does most everyone that I know that raced/races these engines, there is so much oil slash and spray inside the engine,especially from behind the front main and front cam bearing journal the timing gears will get plenty of oil on them.

MBHD,
I keep the oil director to lube the gears, on a turbo car the pressure of opening the exhaust valve is very great because of the extreme cylinder pressure, therefore the force between the crank gear and cam gear is greater, I don't have any problem with a lack of oil pressure or volume with a HV/HP oil pump.

Just my thoughts,

Harry

Sent a email out to all contributors. It is the schedule of tests to be run. If anyone was missed please contact me.

There is one recieved over the weekend not added to the list. Will be this evening.

Got a bunch of test scheduled. Have atleast 7 cams to choose from and 4 different head configurations. Testing a divided port and maybe will even turbo it! Blow thru down and dirty. Tom

Any requests?

Had a present sitting on the porch today! 6 shiny forged pistons all wrapped up pretty. Looks like I have some work to get done now. Tom

Pics would be nice. Hint ,hint.
What are they flat tops?
No valve reliefs?
Dished?

MBHD

I didn't get schedule, will be in Iowa today and one day next week,

Just got back from the shop. Block is now deburred and the cylinders are chamfered. Then worked on some heads.
Block will get honed next with a tq plate and head studs. then cleaned again for final assy.

Jalopy,
I sent the email out the same as with the 292 tests. Checked and you are on the list. Will send out again. Subject of email will be 250 dyno day.

Hank, Took plenty of pic's, wife went to a program and took the camera. Will get some posted later. Tom

Here are some pics of parts and some cylinder reliefs. Tom

The line is top ring travel, or with safety margin of X" added?
Is the width a function of head diameter?

Please ask questions in layman terms.

The top ring land is down .300 and the chamfers go down .150. Should be no ring sealing problems. If you look at the way the valves are located offcenter of the cylinder, these chamfers will remove the sharp 90 degree edge the airflow hits leaving the intake valve. Tom

I'm used to relieving a flathead cylinder (different purpose, obviously), but we normally stopped the relief depth at 1/16" minimum above the highest point of top ring travel, to prevent the ring from getting too hot. They don't appear to suffer any damage from passing right into the relief, provided it's not too wide. If you have to do this, be sure to make a small radius at the edge to help the ring jump in and out (like a 2-stroke exhaust port).
A common recco for valve relief used to be a minimum of .100" larger radius than the valve head.
Depth to whatever is indicated (1/32" is pointless - but it makes you feel better! some engines will take 3/16" deep.
Shape: by moving the 2 cardboard circles (bore, and valve @ OD + .200") away from each other until the crescent of overlap is the relief depth; this determines how far along the wall the cut extends. It's going to look like yours, but easier to duplicate in all cylinders.

What I've never seen done or discussed: without making the relief depth greater, is making a roll-over radius at the top (using as much of the gasket surface as possible) to start the relief helpful?

Dyno 250 Predictions:
Some of you may recall I made some "Gonkulator" predictions of the 292 dyno tests before they were run. The predictions matched the test series fairly well, although I did correct the dyno data horsepower by about 4hp, that is my estimate of a correction to full open headers vs the (2" or 2-1/4 pipes I forget) used.

With that, the Gonkulator averaged same as the dyno overall, with a scatter (standard deviation) of 3% or 4%, ie a scatter of about 10 ftlb and 8hp or so.

So, on to the upcoming 250 dyno runs.
Run-for-run, my Gonkulator is predicting that the 250 will come in about 14% lower on torque and 6% lower on horsepower than the 292. We should be able to see this since 5 runs (as I count them) are repeat runs - the 250 will be dyno'd with exactly the same cam/head/manifolds as on a prior 292 dyno.

One reason the 250 hangs in there so well is that for most of its runs, the 292 only had 8.80 compression. I am calculating the 250's compression at 9.76 with the flat tops - Tom does that sound about right?

Especially fun will be the weber tests, I am predicting well over 300hp for the weber and the biggest cam planned.

With the 70cc heads it will be right at 10.03-1 for the compression with zero deck and a .040 gasket.

With the latest 12 port aluminum.Kirby/Sissle head,mild 250 build that Mike dynoed it & it made just over 300 - 310HP

IIRC? It was in a Hot Rod article?

MBHD

This should make for an interesting comparison. We are expecting to see over 300 with this testing.

MBHD
I think that is the June 2005 Hot Rod?
The 12-port fuelie 250 dyno'd at 315hp, my guess is about the same exhaust restriction as Tom Lowe's plan. Guessing the fuelie setup is about the same as weber power, adding tlowe's hottest cam would add about 20hp per the Gonkulator. Knock off about 5hp for compression (10.5 vs 10.0) so if the June 2005 Hot Rod engine had tlowe's cam and compression, it would have made maybe 315+20-5=330hp. I am Gonkulating about 310hp for tlowe's top dyno test, so that means the 12-port head would be adding about 20hp vs the ported, lumped, big valve stock head at this level of build. We will see!!!

I do expect to see over 300 hp.
The compression calculated was also 9.76, but will be lower because of the cylinder notching, should have caught those filings and CCed them(dang nab it).

Yes many of the same 292 tests will be done again and many are not. @ new cam's will be brought into the equation and a set of Langdons sweet exhaust manifolds and to kick it all off in the end , amild blow through turbo setup. Lots of work indeed.

Beater, Your coming , right?

Seriously, there will be some big time wrenching taking place, more hands always lighten the load. Tom

If you haven't closed it up already a little modeling clay can be used to reform the "missing" metal and then cc that.

True, It is not closed up. Just yesterday started balancing the crank. To start the rear 1/2 was nearly perfect and the front 1/2 was off by 18 gms on the non counterweight side! Talk about creative weight reduction. Tom

Tom, just stick a piston in a bore and cc it, then you can just subtract the difference in volume that an un-notched bore is from it. Its the same process you use to measure the effective dome or dish volume of a piston.

Going to work later, so been working on the 250. Crank is balanced to within 1/2 gram front and rear. Rods are also done. Those Crower rods are kinda heavy. 670 gms. But built like battering rams. To handle together has a sound like high quality wrench's have.
Will get the chamfer CC's figured in. Tom

Tlowe,

If you can open up your 194 head,by laying back the chamber wall for better airflow.

Then mill the head as much as possible to raise the compression.

Just a suggestion.

MBHD

Tom,

You still collecting money for the dyno day 250? If so, how much are you looking for and how would I get it to you?

Dodgy,
I am still collecting money for the 250 dyno session. There are a few ways to get it to me.
Paypal to tom@12bolt.com

or send it

Tom Lowe
3063 200th st
Dysart, Iowa 52224

All contributors will be added to the email list to share the info.


Still trying to narrow down to the dyno dates. Looking at the first and second weekends in April. Does that fit with anyone elses schedule? Got lots of fun tests scheduled.

Lower end is all balanced, next to hone block, reclean it and assemble it. Tom

Tom, what's your best guess as to the difference in the cast iron Langdons vs the Clifford tube headers?

Kerry,
I think it really matters to the rpm the engine will see. They will be very close in power upto around 5k and then the headers will come out on top. Difference being 10-15 hp.

To be sure this idea is to be tested.
Planning on testing Langdons cast iron manifolds against headers with a moderate cam or 2.

Also plan on comparing Offy and Clifford intakes again, a bunch of street worthy cams and some not so street worthy along with lumps vs no lumps too.
Even have a fully divided head to mate with a divided intake. Lots of stuff planned and not going to be enough time.

Thankyou to all contributors! I am putting together another sheet with the planned runs (current stuff) and will redistribute it out by the end of week. Tom

Here it goes. Dates are picked.
Fri, Sat, sun April 2,3,4 and the remainder Fri, Sat, Sun April 9, 10, 11.

Anyone interested in helping, contact me.

A email was also sent out to contributors, if you did not get a email from me, contact me.

This is going to be fun, I can almost hear the roaring now. Tom

Had a guy moment, wife took care of that. She reminded me Easter is on the 4th. So no dynoing that day. Still planning it to be a go for the other dates. Tom

Here is a correctly laid back chamber on my aluminum cyl head.



Any thought on this?

MBHD

Sorry Hank, The "194" closed chamber head is not in the cards for the 250 tests. It was proven without a doubt to me that with the same work done to a open chamber head , the open chamber produced more power. The average guy doing port work on his head will not know what is needed to be done for the "194" head to wake up.

I think you are better to start with a open chamber head to start with.

Maybe you could supply that aluminum head for testing. I will provide shipping. Thoughts?

Tom,
sorry to hear you will not be testing the 194 head.
I thought the tests were going to be the same heads tested w/the 292?
Now with you having custom higher compression pistons ,running the small chamber head should show more torque, & you are also running larger camshafts that require higher compression will also complement this small chamber cyl head.

You do not need to the cyl head work yourself. Sure it cost $ ,but that's what it takes sometimes to get the most out of a cylinder head.
That is why there are professional shops that can do this type of work.
Like Sissels,Larry,A.K.A. twisted6 & others.
Twisted6 has done a small chmber cylinder head for a record holding Camaro in it's class.
They made no other changes other than swapping out the big chamber head to the small chamber 194 head & saw a .3 seconds faster in the 1/4 mile.
This same 194 head actually flowed a bit better than the open chamber head that was on there. But that is not where the .3 seconds faster came from, it was mostly from the torque increase from the increased compression, I would think,maybe Twisted6 will chime in on this,as he is directly involved w/the car & knows better than I. Larry?

The port lay out is pretty close to the same if not indenticle as the big chamber head.
The only major difference is the chamber wall is too close & shrouds the valve
With that being said,,,
You need to find a way to properly unshroud the small chamber head to flow equal to the big chamber head.
As I mentioned ealier,the ports are the same. So,it's not the ports that is limiting the airflow.
It's the chamber wall too close to the intake valve.

Do you have old hacked up small chamber heads to try some more serious unshrouding?

An average guy will not know how to work on there heads & get them to flow good,if you do not know what you are doing to a cylinder head,you can actually lose airflow/CFM.

Not trying to scare anyone from working on there own cylinder heads hear.
Are average guys sending you there cylinder heads for you to do the work? If so, why,it's so simple to work on correct?
Plus you need the correct tooling etc.

I can't tell you have many times my friends cylinder head shop have recieved cyl heads that have been ported @ home & basically detroyed the cyl head,& or just absolutely killed the airflow.
Customers even try to do certain machine operations @ home.
Then they send there heads to my friends shop to do a valve job.
Some are so bad,the shop refuses to do any work on there heads.

I do know how to port heads,I know what a good flowing port should look like,but I do not have the experience to correctly do a high performance valve job,I leave that for my friend.
My friend is much better porting than me & has much more experiences on different chamber shapes & what type of porting is needed for best overall CFM numbers.
Not sure why you are asking to borrow my cylinder head as you already have 2 or 3 of the 12 port heads?

My aluminum head has 2.08 intake valves & flows 320 cfm @ .600 lift.
It has street porting ,not an all out full on comp port job,w/bigger valves.
Still a work in progress,it's not done yet.

Seat angles,seat widths,throat shapes,air entry into the port are all very criticle.
This stuff you do not learn overnight ,or in a year,it takes a lot of R&D work.

Not trying to rag on you,I think it's just a better idea to send your heads to a professional cyl head shop than to possibly screw up a cylinder head.
Two cents thrown & then some,sorry for the ranting everyone.
I just know HP & torque all starts w/the cylinder head & to get a great cylinder head working ,most will need to send to someone that knows what they are doing.
I would like everyone to show up/beat up on those V-8 thingys.

Peace!

MBHD

Update.
The dyno has another V8 going on it to break in a cam. He says it will be off on Fri. So the 250 is slow getting in place on the dyno. Hopefully Sat will be a run day. I will also perform runs during the week. The following weekend will be a all out thrash to test as many combos as time will allow. Sat and Sun are scheduled that weekend.

Getting all my ducks in a row and keeping fingers crossed that all goes smooth.
Lots of cams, intakes, carbs, and exhaust to be done. Tom

Goodluck w/the testing & trashing ;-)

MBHD

I second that!!

Me 3

Been working on the weber intake and throttle mech. It has to pull from the side. It has been fully assembled, just needed to make a bracket for the dyno to hook to.
The engine looks good and hope to get it bolted down on fri and get it all hooked up for sat. Start it on Sat. Parts will be flying then. The following weekend will also be a fury of wrenching.
There is so many things to keep track of, feel like I'm getting married or having a kid.

Tom

I sent Tom a writeup with a bunch of computer "Gonkulator" predictions for all the runs. Gonkulator says the low-boost Turbo (mild cam) will NOT make the most horsepower, but rather the webers and biggest cam, 16hp more than the Turbo. But the Turbo computes to make the most torque by far, 66ftlb more than the Webers.

Just for fun I computed each of the dyno builds in my own 63 Nova SS. Street build, 200-4r and 3.25 gears.
Mildest (stock+4v+headers) computed to 16.02 at 82.1.
Hottest cam and webers computed to 14.38 at 95.7.
Turbo / mild cam, the winner, computed to 13.72 at 98.1.

Soon we will know how the computer Gonkulator fares vs the dyno!

Good luck again Tom.

Duece,
Hoping the 250 dyno beats the Gonkulator! Engine is not running yet, but will be in the morning.Your calcs came close last time.

My real work kept me away and could not get enough done tonight. It is bolted down, valves lashed, oil in. Intake/ exh need to go on. The main part is I have to modify the dyno for the 6. The water tank is on the pass side infront of the cam. I move it and all the water valves, ect to the drivers side for the 6's. It takes about 1/2 hr for this. Tom

What damper is going to be used on the 250?

MBHD

Day 1 on the Dyno is done!
Tested 3 cams, 2 intakes and 2 carbs.
Put another rumor to rest.






Offy intake will not perform better than a Clifford. I know this will raise some eyebrows, but it is true. Tested a 390 4 bbl, Truck headers, 1.84 lump head and Clifford 264 hyd cam with both intakes. Clifford produced more tq across the entire RPM range( 2500-5600).

Here are some #'s so far.
Cam 2 Mild street cam 240hp @ 5000 274 tq @ 3800
Cam 3 moderate street cam Offy 252hp @ 5000 278 tq 4100
Cam 3 " " Clifford 269 hp 5500 283 tq 4400
Cam 4 Moderate street cam Cliff 280 hp 5900 283 tq @ 4100

Next goes on a bigger 1.94 valved head, expect more power. Then test the weber intake, the turbo setup and a divided port intake/ head. Lots more fun to go! And no burns.

Have 5 more cams to test. 2 that are bigger solid lift units. Expect to see rpms to 7000.

Will run a few times after work this week and next Sat and Sun if needed. Tom

Glad it all went well.

I would hope you are running a stub stack, or something to help smooth out the airflow into the carb.

As far as the intakes go,,,I would suggest people to try them both out & see what the diferences are. That type of testing would be real world,put it on the street testing.

I have tested both intakes,with many different carbs.

The Offy is the hands down winner also better for mileage.
Now if you want the better top end power by about 3000 + RPM,then yes,, the Clifford would be the one to use.
Just my two cents.



MBHD

Hank,
Have not used a stub stack on this engine yet, did on the 292. Will with the bigger cams.

The Clifford had 4 lbs more tq @ 2500 rpm and 19 more @ 5600 rpm.
How is that not more usable on the street? This is a real world test. Another thing, the engine was more efficient with fuel. Also shown in the BSFC #'s. The tq is there...


You also say people should try both intakes and decide. I agree. Who can afford to have both? That is why the dyno testing is taking place. To put #'s with modifications done, to be logical with parts used, and dispell long held misconceptions about building these engines for the street.

A 280 HP 255 inline 6 is no slouch, especially with a modest cam and a reasonable build. With the next head 10-15Hp will be welcome. Got my fingers crossed. Tom

One of the reasons for the clifford to have run better is the Lump ported head. If you wanted to do a better/fair test try it with out a lump ported head.

JM2¢ on Clifford vs. Offenhauser:
The Clifford 42-4501 has larger plenum volume, which means more mass available to any open valve with the same carburetor flow, but also a weaker signal from the intake valve to the venturi at all times (of course, when engine speed is high enough this fades out).
The Clifford also has a larger radius between the front and rear runners to the plenum, which will improve flow at higher speed.
As either engine size or RPM go up, the Clifford will have a bigger power advantage.
I know it's not within the goals of this test (can't do everything - only the ones that would be helpful to most builders), but IMHO where space permits the Clifford might benefit from 1 or 2" spacers between the runners and the ports (of course, this makes it much wider, linkage and fuel line problems, etc.), and also perhaps a 1" spacer under the carburetor (especially a 390, etc.).

The Offy 5416 looks like what they made out of plumbing fixtures in 1940 to add a second carburetor - and before they were willing to admit that the factory manifolds weren't that bad as to contour and design (just too small). The smaller plenum permits leaner jetting and better mileage at low to moderate speeds with no loss of response.
With a small engine at moderate speed (194, stock cam) the power difference will be small.

Can you pick up cylinder to cylinder mixture distribution differences? Any manifold may also change which runners are favored as RPM varies, etc.

When the 292 was ran. There were temp sensors in every header tube. No differences were found with either intake , cam, carb combo. The even fuel distribution was surprising. So on the 250 I got lazy and only hooked up 2 sensors. One on front and one on rear. No difference in temps seen this time either. Tom

That's a great point as when I ran my tests w/the two manifolds,w/just the adaptor plate, I also tried using 1" open hole spacer,1", 4 hole spacer,2" open & 4 hole spacers.
I did not have any lump ports.


MBHD

That is exactly what I am saying,,,,you would need to try these manifolds out on the street,,,your street car engine does not start out @ 2500 RPM.
I realize you cannot start the dyno pull idle or @ 1000 or 1500 RPM,but cars or trucks can, & that is 1 part of the reason a dyno is not a tell all absolute truth.
Even a chassis dyno is not real world driving situations,you can simulate road driving conditions,but it still is just a tool & should be used as such.
When you actually drive your vehicles from idle & up on the street or track,it will be a different condition than a engine or chassis dyno.

MBHD

With you running this dyno testing it does not dispell all misconceptions,& like I said you cant prove any misconceptions unless you are pulling from idle to 2000 or so RPM

I have always said the Clifford makes more power in the 2000 + rpm range. Nothing is being proven different to me in these dyno tests,@ least not so far ;-)

Yup - stock Powerglide + tall gears needs power at 1,500 RPM for daily traffic. Even many stick drivers don't use 2,500 until their doing parkway speed.

All of that testing was done in the first 292 dyno tests 6 months ago, and the Clifford was still superior then, as it is now. Lumps or no lumps, it matters not. As panic pointed out, the Offy is a much older and cruder designed intake, the Clifford is/was designed in more recent times with a more performance minded clientele in mind..

Well, unless you are running a converter of say 2000+ stall ,low rear gear ratio,you won't mind the sluggish/mushy bottom end the Clifford intake will give you.

Also,, if you have stock compression,stock low stall converter,you will not like the Clifford intake anything below 2000 RPM, which by the way is most of your day to day driving RPM.

I did not mind using the Clifford intake,because I have a junk Darrel Young,3500 stall converter that could only muster up to 2800 & 4.10 rear gears w/higher than stock compression.
Don't get me wrong here,the Clifford intake is a better intake for higher RPM,just not off idle.

MBHD

I have had both but I didn't drive the clifford enough to have an opinion. I will say this, I rarely hit 3000 rpm and with a stick, I want the balls at 1000-2000 rpm. That will be 90% of my driving. And yes, I'm just an old fart.

On my stock tired 250, 3-on-the-tree Nova, 3.08 gear, the Clifford did lose some low end on the Gtech vs the 1v intake. Made up for it on top, result was just about even with the 1v. And, the stock 250 (or smaller) is the wrong place for a Clifford, so I don't think it's too bad considering that.

As for part throttle, well, once I got everything sealed, I can let the clutch out at idle - foot off the gas, and take off. True, I can't really floor it below 2000-2500 but it drives off idle just fine, just not as good on gas as the 1v.

I've not driven the Offy (like many others I can't afford both) so this is just a partial opinion, but I am encouraged by Tom's results with the big Clifford.

Speaking of those results:
I made Gonkulator predictions on the 292 before Tom ran the dyno. The dyno horsepower came in consistently lower than the Gonkulator by a few percent. I thought maybe it was exhaust restriction out of the dyno, but now wonder if it was internal friction in the 292, more than I expected/computed.

Because, Tom's first 250 dyno tests are coming in HIGHER horsepower than the Gonkulator, by about 7 percent so far. That 250 is doing really well. Maybe it is a nice loose build, maybe that chamfer in the bore is helping, maybe I was wrong in assuming any exhaust dyno restriction or something but the dyno tests are making me debate whether to build up a 250 or 292.

Thanks for the update Tom, we await more exciting news.

It would be nice if someone could run both the OffY and the Clifford. Maybe they could start another post with the results.



Duece,
When opening the 292 lower end up, the 2 middle cam bearings were mushroomed out. They are durabonds. So bad that the oil holes got covered by smooshed metal. When changing cams, they had to be forced out ( with hammer).
I am sure these bearings were costing power in 2 ways. One in frictional loses and second by allowing the cam to flex against the spring pressure of the valves. Thus causing irratic lift and duration.
The 292 was definately louder than this 250 and I am sure this was the noise. Probably would have gained 10 hp or more with the 292.

The exhaust for the dyno is a good loose design. Just last week a 400 SBC was done and produced 600 hp and 590 tq. It sounded sweet!

W/the 292 ,4.120" stroke you are dealing w/alot more harmonics I would think than the 3.52" stroke of the 250.

Harmonics absolutly kills power of the engine.

I did test both intakes & various carbs & raced against my friends dead consistant street car, it was not just a seat of the pants test.

I guess it's hard to imagine what I've been saying about these intakes "is what it is".

DeuceCoupe ,compared a Stock 1 bbl carb to a 4 bbl clifford & the results were the same,w.a Gtech,which BTW are pretty damm accurate.

The stock 1 bbl carb will actually take off better than a 4bbl & Clifford,,,imagine that.


MBHD

Was at the shop after work. Changed the 1.84 lump open chamber head to a 1.94 open chamber head. Got it all hooked up, valves ran and water in engine. Will fire it up on tues eve and see if it makes more power, it did with the 292, so am assuming the same here. Fingers are crossed.

This head has 1.94 intakes and 1.6 exh. Both are Ferrea. Using Comp cams new ultra magnum rockers, they are nice. This head has the HI-FLOW bolt in lumps installed as did the 1.84 head. Tom

I thought the 1.84 lump head is an open/big chamber head?

You can save some money & get just as good quality valve as Ferrea valves if you are interested.

MBHD

There all open chamber heads, its just a figure of speech im sure.

Yes, all the heads I am running are open chambers.
70CC chambers.
What brand valve are you reffering too?

I've never seen a Gen-3 open chamber head.

Panic, these heads are all around the 72-74cc range and were the production heads on most 250 and 292. The 194 casting heads are the smaller chambered ones and end up being in the 60cc range when big valves are added and surfaced a little bit.

Some casual video.

http://www.youtube.com/watch?v=5uVNQFkIZXc

Sorry, I meant that they're all quench (part of the chamber surface is flush with the gasket surface), and the bore isn't completely exposed at TDC. An example of a wedge chamber with inclined valves, but open chamber is the Chrysler B/RB 906 and 452.
Except for intentional smog (like these), some 2-strokes, and some hemis, closed is pretty much universal (and mandatory on sidevalves). All 4 valve and pent-roof I can thick of are closed, although the "closed" sections are really small.

Yes, they all have quench and are not like the 906 or 452 heads.

Ran the 250 tonight with the 1.94 open chambered lump head (70 CC). Made another 5 hp. Our weather is crap right now, with high humidity and changing temps. It also moved the rpm range slightly higher, now the dyno is set for 6500 rpm. Peak is now 6100-6200 rpm.
A 390 Holley will flow 420+ cfm also, It is now a limiting factor. On goes the 600 holley. Tom

Next things to try: Same cam/ head
Langdons cast iron headers
Weber intake/ carbs with headers
4 more cams
The crude turbo setup.

Thankyou to the guy's that are still contributing. Anyone missed by my emails, do not be shy. I have a sending list that just gets added to. And no it is not too late to help. This weekend will be a busy one. My email is tom@12bolt.com .

If the dyno guy offered his 650 DP, I would throw that in the mix as well.

My 65 SS Malibu V-8 350 SBC loved that 650 DP I put on it.
I know I said the "V" word sorry.

Sometimes what does not work on paper/calculations, actually works in actual testing.

Case in point, a female street racer/track car years ago had a 64 Nova SBC 350 w/a Weiand 150 size ? super charger. All the calculations ,blower books,B&M caculator, etc,said all it needed max,was a 750,which is what she was using (750 DP).
Well ,they had an 850 DP carb lying around & said ,what the heck,lets try it, well gues what,she ran 1/2 second faster in the 1/4 mile.

Morral of the story,,,think outside the box of time & time again proven recipes.

I was always told the 48 DCOE Webers were too big for my 254 L6,,,but with even that being said ,I ran them anyways,the Webers I ran w/12.1:1 compression was the fastest my 254 ever ran normally aspirated,period.

Heck, I bought the DCOEs for $200,,so I could not loose, even if they did not run good, I could always sell them for more than $200,right?

4 bbl carbs are a different story as compared to DCOEs,but w/all my trials & errors & R&D through the years,& even tried a Thermoquad 850 CFM carb,just to see how it worked on my 254.

Have you guys ever heard of anyone trying to use an 850 Thermoquad carb on a 254 CI L6?
I was young & foolish maybe,but @ least I tried many different carbs & a couple intake manifolds for the ultimate quest & search for the most power I could get out of my Chevy 250, +.030 = 254.

I think a 650 DP could be managable. Just a thought.



MBHD

In the video, the last pull seen was the 3rd of 4 pulls. After the 4th pull. The 650 DP was put on and tested, lost tq across the range and also down on Hp on top end. We did try. It almost never hurts to try.

Langdon cast headers are on and will be tested on Thurs even. Same cam and 390 carb. Tom

Yeah, I kinda was thinking it would loose torque & HP,but @ least you tried it.

I had the best luck w/ Carter AFB 400 & 500 AFB's,I even used a couple Carter AVS 625's,but it seemed a bit too much & could not get the secondaries to come in at just the right time.

When you get the side drafts on & working good,the torque increase should be a big amount.

Any guess on how much HP loss w/the cast iron headers?
I am guessing not too much if any by this engine build,but hey, I could be wrong.

MBHD

It would be interesting to see what a good QJet would do. Say one off a low HP 327. Adjust the air door rate and max open position to dial the airflow back. The stock eliminator guys make em fly...

Tom, do you think perhaps a 650 vacuum secondary would give better results??? They are in a sense "self regulating" in that the primary airflow creates the signal to open the secondaries....even though rated at 650 the end result could be 550-600 deoending upon the engines needs......based on efi's input: didn't G.M. put a q-jet on the pontiac ohc 6?.....time and expense are factors I know but it might be worth a try if you have access to either one......checked out the video; great stuff you're doing.....for years I've been running on seat of the pants feel and gut level intuition, good to see some hard data.....fats

The Pontiac Sprint 4bbl engine had factory installed spreadbore Q-jet carbs,I even pulled them off those cars from a junkyard.

I just heard they were 650 CFM Q-jets, but I did not think GM made A 650 CFM spreadbore Q-jet.

Maybe the old style squarebore Q-jets were that size?
MBHD

Hank and KS,
Yes I heard same about the Pontiac OHC-6, as I heard it those Qjets had a very stiff air valve so that where rated (std 1.5" Hg) the air valve was still partly shut, on purpose, so they did not flow the normal Qjet 750cfm but rather only 650cfm.

I've not heard of a 650cfm vac sec Holley, just a 600, then a 715cfm downleg (excellent carb) first used in 1963 on the 427 Ford.

I think the 650 Double Pumper is still a straight leg booster like the 600 Vac Sec, and the added 50cfm of air is likely not needed. To get dogleg boosters you'd have to go to a 700 double pumper or the 715 vac sec.

So if the 650dp didn't run as good, it is likely coming down to which carb the engine "likes" better. If it is happy with the 600, that is probably the one to go with.

I think you could do an entire dyno weekend just dialing in a carb to a given combo. Then, if you changed cam, intake, or headers, it would no longer be optimum. All you can do in a short weekend is have a carb that all the combos are fairly happy with and show good AFR. I don't envy Tom's rushed task, it is easier for me to sit here and type.

All the calculations ,blower books,B&M caculator, etc,said all it needed max,was a 750,which is what she was using (750 DP)

There are variables we don't know, but just a guess:
350" @ 90% VE, 6,000 peak power = 547 CFM @ 1.5" Hg vacuum.
10 psi boost at sea level (14.7 etc.) is 1.68:1 pressure ratio.
547 × 168 = 919 CFM.

The QJ air door (secondary air valve) rate can limit the total CFM on the back side if the spring is tight enough, but it also controls the secondary metering rod position (on a Holley, the diaphragm can be anywhere, and the PV still opens when you want), so if it's tight the motor gets less fuel. Not opening to 90° also creates a flow bias which will affect front vs. rear if the carb is positioned with shafts across the engine (like on a V8).
A TQ works pretty similar, but has an extra tuning headache: the air valve linkage is part of the choke linkage, and getting them both to work (on a street car) took several hours (Chrysler 360).
A 250 would have to turn pretty fast to get an improvement with a 650. Assuming 95% VE, even 7,000 RPM needs only about 529 CFM. If I were trying a 650 here, I'd run slightly smaller high speed bleeds to compensate for the lack of WOT vacuum rather than rely entirely on PVCR changes.

Ran the Langdon headers tonight. They sure quiet down the entire engine. Fit was great and sealed perfect. Tq was down as to be expected, but they held their own until the rpm got up there.

All I can say is they don't give up much to the headers and would be perfect for a reliable sealed exhaust on a peppy street build.

Taking a vac day for Fri. Webers are going on. Got my fingers crossed that all goes well. They tune much differently than I am used to. It will be interesting.

The turbo and a bunch of cam changes are set for the remainder of the day and Sat. Will save a big cam for last. Tom

Videos please. ;-)
The last one was excellent!


MBHD

Thanks, but that one was crued. Really works best when my daughter tapes, she knows how to film, nicely. Will certainly get more vids, I have lots from the 292 and more from the 250. Believe me they are getting taped in HD 1080P. I can't download from home. Used to when the movies were made with dig camera, these HD 1080 movies are giant in size compared to those. Tom

Ok , back from a long day at the shop.

Ran the 3 side draft setup. It was somewhat of a bear to fit it up. Hit the front header tube, also the header tube braces. Sanded the intake to fix that.

Engine started pretty good and idled high, had trouble getting a good idle. Ran some light pulls and found good tq readings and response. Decided idle was not so important and ran pulls to 6200 rpm. tq would hold 290+ for more Rpm than the 4 bbl did and saw the first 290+ hp #'s. Strangely the hp would drop about20-30 hp at the same place it did with Langdons Headers.
So we put the 4 bbl back on and duplicated the problem, after checking valve springs, ignition and compression it was found out the balancer was loose.

That is where the problem lies. Harmonics have got me by the tail. On Sat the motor is getting pulled and opened up for inspection. The balancer was wiggling and upon trying to pull it it wedged, so decided to wait till morning for a cold engine.

If needed, I have more cranks and can balance it for installation. Also have a good quality HP GM balancer. Still have alot of test planned and hate to quit now.

Well enough for today, just poured a big margurita and going to watch a movie with the kids. Tom

That's too bad the damper did not do it's job.

When I was using stock damper,my engine would only turn to 6000 RPM or so,but struggleing to get there also.

I did nothing else to my engine but install the 8" GM damper & man,what a difference! Smooth up to 6000+ RPM.
It wanted to rev much quicker also.

I later installed my Paxton supercharger blowing through 3 48 MM Weber DCOE's & it would want to go to 7500 RPM

I run a stock 8" HP GM damper. This damper totally smoothed out my engine & I turned to 7500 RPM w/it,not too wise w/a cast unit,but I did so anyways,because of no money @ the time.

I have heard good things & bad things w/fluid dampers.

My new engine will have a Vector damper.

Sounds like another test w/a good damper & Langdon headers .

MBHD
Previous quote" Any guess on how much HP loss w/the cast iron headers?
I am guessing not too much if any by this engine build,but hey, I could be wrong"

Sorry abut the trouble. How was the movie? Tom

Quite relaxing. Thankyou. My boy is 10 and said proudly it was rated R. So then we watched it. Cloudy with a chance of meat balls. I think his R rating was meant to be Really funny for kids.

Packing up stuff to take to the shop,
crank
balancer
bearings

Got my fingers crossed for the teardown/ inspection. Tom

What damper are you going to use now?

MBHD

He used a Fluidamper on the 292, maybe he'll stick it on there.

That was the damper that failed.

We took the engine from the stand and opened it up. Flywheel shook loose too. Bearings all look great but the crank snout is destroyed.
Had 2 spare cranks. Measured them both up, picked the better one, balanced it, polished it, cleaned it and put it in. The engine is now back on the dyno with locktighted flywheel bolts and a GM HP 8" balancer. It balely cleared the Clifford 2 peice cover. Had to remove 2 bolts from cover for it to clear. Ready to start on Mon. Tom

The only way I had goodluck from the flywheel bolts from coming loose was use red locktight,metal foldover tabs,then on top of that I used JB weld over the bolts & foldover tabs.

But all this shaking & coming loose was due to using a stock L6 damper,after I used the 8" HP GM damper,my engine totally smoothed out.

Yes ,if you use countersink screws on the clifford timing cover,it clears the damper.

MBHD

Tom was this the fluid damper off of the 292?

What is the 8" GM HP damper you guys are using? Is that a small block v8 part?

The 250 was using the fluidamper that was also used on the 292. The crank snout is toast. Will get pics. It tried to weld to the timing gear and crank snout.

The GM 8" HP balancer is a GM performance part for 350 SBC. It is used on all ZZ4 crate engines and is the same one used on the 1970 350 LT1. Had to recreate the timing tab as the 8" diameter was much larger than the old damper.

I know the V8 damper produces better results than the original (or none), but the actual tuned RPM doesn't align with the bad patches in an L6 except by coincidence.
How fast the motor turns only determines how many vibration points it will reach, not where they're located.
The factors that determine this are mostly crank length (number of cylinders in a row, number of main bearings) and stiffness (journal diameter, journal overlap, stroke length), and a SBC is much shorter with the same bore pitch, 2/3 the # of cylinders (+ 1 rod width, etc.) in a bank than a 250. This extra stiffness moves the RPM points wayyy up on the scale, which means the 250 will not reach most of them (and may not line up with any).
To actually predict how many do, I'd need the resonant frequency of a 250 crank in Hz (the 194, 215, 230 cranks will be almost identical, the 292 slightly lower).
Just a guess: if the 250 is 230 Hz, its critical points will be the 3rd at 4,600, 2-1/2nd at 5,520, and 2nd at 6,900 RPM (the others are weaker). Even a long, weak V8 crank (Buick nailhead) is over 300 Hz (up to 450); let's use 350 Hz which gives critical points with the 6th at 3,500, 3rd at 7,000 and and 2-1/2nd at 8,400 RPM (the 2nd is too high).
There is a nice match at 6,900 - 7,000 but it's the only one, and it depends on the data. The entire range from 3,000 to perhaps 6,700 has no matches.

Does this damper require any machine work to fit a L6 Chevy and being 8" cause any interference with the water pump pulley and belt alignment..??

Part #12555879

Recommended source?

Scrapiron: My small block Streetdampr I shortened the damper hub to tuck the damper in as close as possible to the timing cover. Next time I'll counterbore the timing gear instead for a more robust damper connection.

If you don't mind the damper sticking out a bit then I think it's a bolt on deal without modification. Can't say for sure on the GM damper but it's probably similar.

Panic, is thet stuff always going on in your head? It must hurt sometimes. No wonder you used to be so cranky! Wow, That is a lot of thinking. So you are saying that the charistics of a given crank can be used to predict at what rpm harmonics will cause problems and then a dampener can be built to even them out at several different rpms? I thiought they just kind of deadened them as they came by. Beater

I would think cranks can also be balanced so it will run smoother @ high RPM & run a little rough in the lower RPM range.
I'll ask Dave @ "The Balance Shop"

When I used to road race a two stroke GP bike & other 2 stroke engines,I keep on breaking cranks because the class made us use the stock heavy flywheel.

I had my friend Dave @ The Balance Shop ,balance the crank so it would run smoother @ high RPM ,,& it did just that,a lot smoother & just pulled cleaner all the way up to 13,000 RPM,eventually the crank still broke,but it did last longer than w/a stock crank & with stock/original balance.

Originally the engine turned to 8500 RPM,& the crank would last a full season.


MBHD

the charistics of a given crank can be used to predict at what rpm harmonics will cause problems

Yah, but the analysis is really complicated even using ex$pensive software. The point is not to detect some metaphysical, sub-atomic internal property, but to find out when a given piece of metal will ring in sympathy to an external shock. It's just a big, weird-shaped tuning fork (no power or compression forces apply here) and it "rings" at a certain frequency - long and thin makes a deeper tone (lower Hertz frequency) than short and thick (higher). Big bearings raise the tone, long stroke lowers it.
Depending on the firing order, number of cylinders, bank angle etc. there are specific "orders" that will stress the crank, and frequency determines the RPM at which these occur.
Where “O” is the number of the order, and Hz is the frequency
RPM = Hz × 60 ÷ O
Hz = RPM ÷ 60 × O
For an L6, the critical orders are (strongest harmonic first) the 3rd, then 2-1/2th, 2nd, and 6th (the 9th is smaller, 1st is outside the normal RPM range).
I made a stab at how it might be estimated by suspending the surgically-clean, undamaged crankshaft in a soundless environment, and either:
A. striking it smartly with a brass hammer, and using a microphone to record the sound, then reading the oscilloscope trace to get the frequency, or
B. using a tone generator to excite the crank by slowly passing through the suspect period (200-250 Hz for an L6) while intently watching an attached .010" wire for vibration?

No one thought it will work, but they couldn't say why.

Measure the torsional stiffness by torque versus deflection. Then measure the polar moment (correct term for rotating inertia?) by hanging from a soft spring, twist and release, and measure oscillation period. Combine the two and you should be able to calculate natural frequencies.

I think so anyway.

Hank, thats called "over balance", we did it. Winston Cup and many race classes that have engines that run in the high RPM range like that also have done it for 20 years or so. It definately helps. Its easier to do on engines that use bobweights to balance them, because you just cheat the bobweights by the amount you want to "over balance" it. On an inline that doesn't use bobweights, its a little more difficult, but it can be done.

So how exactly do you overbalance in inline? Add 100g bobweight to each crankpin? I'n not sure what that will accomplish. Please explain.

Measure the torsional stiffness by torque versus deflection

But... that's not something I can do. The crank flexes in normal service perhaps 1/4 to 1/2°; I can't make an accurate measurement that small, and I'd need a fixture sunk into the ground to anchor the crank (my lathe only weighs a few hundred pounds, and will lift right off the floor).

If you examine the crank, there are huge counterweights to both provide inertia and oppose the dead weight of the rod throw 180° away.
I've read many articles on L6 balancing, and have yet to see a specific recco as to what mass the individual counterweights carry, or even the total imbalance.
Obviously, 100% of the rotating weight is included (pin, arm, bearings, rod big end), but what (if any) opposes the reciprocating weight?
Why are some counterweights heavier?
The only definition is what it's not: it isn't a percentage of the reciprocating weight (which is what V8s require).

An example of a very complex analysis of crankshaft design, with almost nothing on exactly what determines counterweight mass:
http://www.bacomatic.org/~dw/library/angle/angle.htm

Just a thought: the well-known "perfect inertial balance" of an L6 is not a physical analysis, but theoretical.
In practice, each pin and its components is opposed by another cylinder on an opposing stroke (unlike L4, V8, etc.).
Where's the difference?
The other cylinder is (at best) next to it (not exactly opposite) such as the #3 & 4 (the balanced #1 & 6 are at opposite ends, duh), and the forces between them bend the crank at the web connecting them. The counterweight provides opposing weight as close as possible to the actual pin (on both sides).
But, again, what does it weigh, and why?

Here are pics of a few things.
bad balancer/ crank
Langdon cast headers
3 side draft OER carb setup.

By my understanding:

Inline six counterwieghts are there to reduce crank bending loads and bearing loads. They do not contribute to a smooth running engine in terms of externally felt vibration.

Not true on other engine configurations such as v8. v8 has unbalanced forces and will vibrate externally. The externaly felt vibrations can be altered by changing the recip factor or under/over balance.

For example, balance factors on motorcycle engines are chosen so the engine vibrates fore/aft instead of up/down for rider comfort.

A torque wrench, dial indicator, and a little creativity will get you torque/deflection.

Polar moment of inertia (not sure if this is correct term?) is a little tougher but also obtainable with a stopwatch and some more creativity.

Combine the two and you should be able to calculate first order natural frequency of the crank, damper, flywheel assembly. Don't ask me to do it though, my math is rusty.

Im surprised to see this in a 250. You usually have these type of issues in a 292, with loose flywheel bolts and balancers.

Panic, you may give the people at http://www.bonal.com a call. Their equipment is meant for stress relief but finding the first harmonic frequency is a required step to using the equipment properly. Very knowledgeable folks on harmonics.

But, again, what does it weigh, and why?

Panic,
When I built my 321 inch Jimmy I used a 308 Hudson rod, Pontiac pin and a custom JE piston. I saved more than 1.25 pounds per cylinder. I tried to find out how much weight to remove from the crank counterweights to compensate for the reduced weight but was unable to find anything.

Any thoughts/formulas,etc?.

Ron

I believe,what ever you remove from recipricating (SP) weight ,should be the same amount of weight you should remove on the counter weights,,,but that's just a guess.

At least that's what I remembered that was removed from when I ran a lighter or heavier piston,on a single cylinder MC engine.

MBHD

Single cylinder engines like that and the Briggs 5 HP engines are balanced with a bobweight, and probably don't follow the same principles as a "neutral" crank that doesn't use bobweights for balancing.

Had the 250 running again this evening. Sounded good , again. Idle is a little different with the heavier balancer and 5 lb heavier crank. Oil pressure was also good. While warming it up found a oil leak from one of those removed timing cover bolts. Blah! Thought the bolt hole was blind on the back side. Cleaned it and sealed with silicon. Let sit overnight to dry. Hit it again on tues. Tom

Wow,,that damper took a beating. Looks worse than any of mine that went bad & in much less time.

Are you going to retest the Langdon headers again?
I am thinking the damper was loose on those tests & caused a loss in HP @ the upper RPM range (due to vibration) where you stated they held there own until the upper RPM's.

MBHD

Hmm

Looks like the fluidamper was loose on the crank. To work effectively the need like 0.001-0.002" interference fit.

Comparing the Langdon headers verses the long tube headers dyno data, surprisingly, the big difference was in the low 2500 to 2800 rpm range where the long tube headers delivered 13 to 20 ft.lbs more torque. The 1500 to 2500 rpm torque readings would have been interesting, if they had been available.

Any info on what size and style the side draft carbs were?

Panic:

Inline six counterwieghts are there to reduce crank bending loads and bearing loads. I don't know but suspect this is the reason GM changed form 6 to 12 weight cranks for 250/292 engines. Weights opposite each crankpin should result in less crankshaft bending and lower bearing loads.

As to how much, I expect that is a compromise of cost, manufacturability, crank fatigue durability, and bearing life.

As mentioned above, removing counterweight proportional to reduced recip mass is probably a safe bet.

ACH57,
The side drafts are 45's, fitted with 36mm chokes, also have 40 mm and 32mm chokes available.


The balancer had a nice fit for both the 292 and the 250. Who knows what could have went wrong. Tom

Should use the 40 MM chokes.

My 48's had paper thin chokes, like 46 MM.

It's take a lot of time & lots of jets to get them dialed in,not to mention the correct emultion tubes.

MBHD

May do that yet.

On tues night, the motor was back up to snuff making 285 hp. Tonight, bolt on the turbo stuff, turn down the timing and see what happens. Might not run tonight, but will try. Tom

All the turbo stuff is bolted on.
Thurs after work, will fire it up with out the turbo charge tube and get carb setup, make a few light pulls. Then turn down the timingand get the boost dialed in and nail it. When You see the pics (none taken yet) it is a throw down turbo setup, yet funtional. Tom

I'm back from the shop! Got a few trophy burns this time too. Turbo motors have more hot parts!

Used a SPA turbo manifold, turbonetics wastegate, a old Air Research T04 and a holley 500 2 bbl carb in blow thru mode.

Wastegate held the boost perfectly at 5 psi and we saw a 33% gain in tq! 87 Ft lbs to be exact. This little 250 thought it was a good running 350 chevy. Also saw the 345 hp in the #'s. But the tq was king for the runs.

It was a crude setup and put together from scrouged parts. This was done mainly to show how easy it is and some of the power gains that can be seen. We had hoses blow apart because there was no blow off valve. So when coming back down in rpm from a pull the throttle had to go slow to not build up excess boost and blow the hoses.

All in all, it was a success and definately more power can be had from this turbo setup. Boost was almost instant and the engine never missed a lick. What a fun night. Got plenty of vid, I think my hands were shaking from the excitement. Plenty of tuning needed to be done. Tom

Very nice!

If I had know then what I know now, I would have turboed a long time ago.


MBHD

Thats awesome Tom!

I'm stoked to see those kind of numbers from very limited boost. It seriusley makes me consider a hairdryer for my car. Curse that shock tower on the Chevy II front subframe...

Can't wait to hear some more of your opinions from this set of dyno day. Awesome work as always.

-Sam.

Sam, for inner fender well clearance issues, theres always a Paxton or Vortech....I'd like to see what 15-16 psi will do with one of these on a 292 for the street.

Oh I've considered retro-fitting a centifugal blower. The boost would be a joy! However, the initial start up of buying a blower keeps detering me. After I get the car on the road though, then I can start saving pennys for some compressed air..Who knows how many years that'll be, haha.

If that 250 took to making that much hp and torque with only 5 lbs of boost...15-16 with a 292 would be a terror. I like the idea...:D

-Sam.

There are many aftermarket front subframes for the early Novas.
You get way better suspension, brakes etc, then the SPA manifold should work.
You guys that dont want to go that route,just run a stock or SPA exhaust manifold & run the exhaust pipe to the turbo on the passenger side.
Or , run the exhaust pipe to the front on the drivers side in the same location as Bosanovas.
Tlowe, what are the specs on that old turbo? T4 .96 Turbine side?

MBHD

Thanks guy's!
It was alot of fun. That little 250 would hunker down and pull. With 10 psi, bigger carb, intercoller and timing control it would scream.

The turbo is a .94 exhaust housing , it boosts great. Originally came on a Old Accel V8 turbo kit. Imagine that turbo on a 350 SBC. Way too small.

Here are the vids. and more. I have a bunch

http://www.youtube.com/watch?v=PLmUO-fJtH0
http://www.youtube.com/watch?v=9QOdLPA7N68&feature=email

Cool,
your video says it's a .96 housing. No biggie.
What kind of torque did it get up to?

Are all the tests using pump gas,91,93 octane?


MBHD

Sorry, it is a .96, get mixed up with all the #'s. Tq in the 340's were seen, it was always above 320 ish.

Add a intercooler, adjustable fuel pressure reg ,10 psi and look out.

The timing was run low to be conservative with the DIY setup, mixture was also rich and the fuel also conservative with 110 sunoco. No need to damage the motor for simple tests. So more power can be rung out of even a 5 psi setup. Tom

Cool,conservative on the timing? 20 total? It seems you run a good amount on your elky.

How rich was the A/F?
MBHD

Remember Tom's ruinning EFI on the elky - much more precise and controllable

I know that but,, IIRC Tlowe runs about 30-32 degrees on the Elky?
20 to mid 20's on my Syclone is considered agressive timing.
But stock boost pressure is 14.7 PSI.


MBHD

I do not run 30-32 degrees on the Elky. Atleast not at WOT under boost. On the highway, yep run 45 at times.


Started this DIY turbo 250 with low timing (25) and increased it with our comfort level, esp with the minimal amount of control the engine had. Ended at 29 degrees. I am sure with a intercooler, the right compression, cam, ect the timing could go much higher. Not what we were doing here. Just trying to show what gains could be seen with a throwdown turbo setup. Tom

Sent out the turbo data, anyone not getting it, contact me. May change to a divided head and intake this evening. We will see how it goes. Tom

Tom,
I see that in all of your pics with the Holley that the carb is oriented 'parallel' to the head. I've read that it should be turned 90 degrees for a more even fuel distribution to all cylinders. Is what I've read been correct? Or did you do this due to ease and the fact that your secondaries are open all the time during the dyno tests.
'Parallel' orientation makes the throttle linkage hookup VERY easy. I say this due to the amount of time and effort it took for me to get my linkage fabricated to hook it up with 'perpendicular' orientation. Which is recommended for a street chassis or doesn't it matter?
Keep up the good work!

For street use, I have also mounted the carb like you suggest. Bellcranks can be very hard for some guys.

With the dyno being WOT most of the time, it really did not matter. It was also easier to hook up the throttle, except for the side draft intake.

I suspect that bell-cranks may be commercially available as aircraft controls or battle-bot parts, will keep looking.

Panic, try these guys; bought some from them years back: http://www.columbiaairmotive.com/index.htm

Mr.Gasket has offered them for a long time for use with tunnel rams that have sideways mounted carbs.

Here is the last pic.
Picked up all the parts from the shop. Had them on the truck and thought, perfect moment to capture. You will also see the dyno 292 sitting there. Glad I have a BIG box on the truck.

Nice assortment of parts.

BTW,who made that torque plate Goodson?

How did that long runner 4 bbl intake work?
Must have been a pig in the low RPMs?
I never ran one of these intakes,just going on looks.

MBHD

Achkhmmm?

The 2 stools are an anomaly. Can't imagine you had much time to use them!

Sure have plenty of time.

Man Tom that is a lot of stuff! It gives us a better Idea of what you did and ho many times you did it. I have not located the new Car Craft yet, but I'm looking. Beater

I heard the Car crafts are all sold out! It has a red mustang on the cover and is the July issue.

My daughter, who usually will not be caught dead talking to me, was very eager to take pic's ( from a lofted up forklift perch). Maybe someday she will think I'm ok. Tom

Drew,
Good point! They were used very briefly at times. Now I just need to get all the parts organized and get the 2nd Elco in the shop. Time to make it power it self. Getting tired of pushing it around. Let those stools collect some dust. Tom

Tom I really enjoyed the visit we had in Cedar Rapids! I really enjoyed the DYNO sheets! You've really out done yourself and are a great credit to the club. Thank you - 1 OL REDNECK

What is the thing with the Car Craft? Did I miss something?