Inliners International Forums General Discussion Hi Performance Performance Enhancements for a Chevy 250

Your car is great!
I love most any Buick from 63 to 72. I'm currently working on a 64 Wildcat (I hate to admit on this forum because it has a nailhead in it).

If I were you, I'd keep the 250, keep reading, save some money and crank your 250 upto 250 or better horse. In that lightweight car, I'm sure you'll be pleasantly surprised.

Definitely do something with the three speed. I know your pain. My son and I just did about the same thing you your doing, except we did it in a 67 Chevy C20 (quite abit heavier than your Special). We ran it in the original form for about a two months before we started tearing it apart and, I have to say, the three on the tree was unbelievably AWFUL to deal with. Absolutely no power on the highway until you hit 55 or so (several minutes into the acceleration), we were in disbelief that it was made with that trans and engine in such a heavy truck.
We put in a T5, and WOW, what a difference. Then we went through the engine and that helped more than the T5 did. I strongly recommend the 5 speed.

In case you forgot how I started this - that is GREAT car in great original shape.

The nice thing about a hot rod build up is that you don't have to do it all at once. You may find it easier to do if in sections. I looked up your make model and year and it said a six came with 3.23's. Which would be a good match for you. I'd double check it to be sure. Another thing is what kind of gas you'll be using. While a higher compression ratio 194 head may help the compression, it won't help your pocket book unless it's dirt cheap. Also, be careful, some 194's came with Siamesed exhaust ports. They haven't made them in years. You might be better off using 307 flat top pistons and the stock head. What ever you do, enjoy the fact it is a unique car that's all yours.

Just a quick comment.
The 194 cyl head I used when my car ran the best normally aspirated ,12.1 compression,happened to be a Siamesed exhaust port type.

I will double check if for sure, as I had a few 194 cyl heads lying around.


MBHD

well I don't mean it like that. I just want to keep the block. That was the basis that it was built on so I want to build on it even more. I don't plan on selling it any time soon ;-).

actually, now that I look at the T-5, it looks like a fantastic option over a muncie or saginaw. But here are some concerns... It looks like it was used in 80's-90's cars so would it still fit the splines for my driveshaft and clutch and would I need a new bellhousing? Because that seems like a LOT of money.

T5's came in S10 trucks also, and they seem to be the better choice for swapping in to other early trucks because of shifter positioning. I see them in the classifieds in our local paper and craigslist all the time for less that $100 bucks from time to time.

Snowman,
Way Phat video you made, I like the pop-up comments.
Over the years I have found at least one practical use for high school math and physics - I built my own computer program for torque/horsepower and et/mph. So I applied my "DeuceCoupe Gonkulator" to your car, and your dad's Stage 1.
The Car Life road test of a 1968 400-T400 Stage 1 shows
14.40 at 93.0mph
My Gonkulator computed
14.80 at 92.2 on its first try, and
14.47 at 92.6 after upping traction a bit.
About the only practical change that helped was a modern 2-1/4 Flowmaster or SuperTurbo exhaust, computed to
14.30 at 94.0
So, if your dad runs a well tuned stock Stage 1, that is what you'll be up against. Can it be done?

Well, nobody road tested a Special 250-3spd that I know of, but the Gonkulator computer said you will run:
18.38 at 72.3mph
If the engine is in good shape I'd suggest taking it to the strip and try it. You'll never get that bone stock data again.

I swapped in a T5 and 4.10 posi for a computed
18.05 at 74.4
That is actually a big improevement, but there is so far to go.
Note, I've not done a T5 swap (yet) but per your questions above, if you can, hit the yard and get everything from flywheel and bellhousing through the driveshaft. A good yard will make a nice deal on all that stuff, then you have it all.

Well back to the story. Your 6cyl now finishes the 1/4 mile about 400 feet behind your dad's car. It would be hard to tell a Skylark from a Chevelle at that distance. What to do?

If you're following Tom Lowe's 250 dyno test series in the long thread below, Tom's first step is a stock 250, plus 4v, plus headers. I did this to your computer car and Gonkulated:
Stock 68 Special, 250-T5
Single 3" exhaust or dual 2-1/4"
250+4v+headers
16.51 at 82.0mph
That will feel like a whole new car and will now give some 289 Mustangs a good run but not your dad's Stage 1.
So I went right for the limit -
The last dyno run Tom plans is a fairly mild 250, with a low boost Turbo. I put this very streetable engine in your car and the Gonkulator said:
14.23 at 96.9mph
You and your dad will be right even to 60mph, but you should finish about a carlength ahead. A race that close is a real rush, my wife has had one or two of those herself and loves it.

I didn't think that mild turbo would take on the Stage 1, but if Tom Lowe's dyno results turn out like the Gonkulator says, it is possible. Stay tuned.

Nice car BTW!

Thanks DeuceCoupe, I have a question though... what is 4v? when you say "250+4v+headers"? 4 barrel? and I don't plan on putting a turbo in it because of the expense and my FIRM belief that turbos should ONLY EVER be put into 80's+ cars.

Back to some T-5 questions... would the length of the tranny and the position of the shifter be a problem for my bench seats? for people who haven't read... THIS IS IN A 69 BUICK SPECIAL DELUXE (with a B post). Which is a coupe. NOT A TRUCK. and what new stuff would I need as opposed to going with a saginaw (which I already have a 3 speed of in it) or muncie? Wouldn't I need pretty much a new drivetrain besides the rear end as in the clutch -> bellhousing -> tranny -> and driveshaft? I just checked and the clutch plate center diameter needed for the t-5 is smaller by a 1/16 of an inch. Could I use the current mechanical clutching setup I have in the car now? or would I need to get a different one for the T-5. Besides those questions, what is specific to a transmission? I'm assuming the clutch plate and driveshaft for sure because of the diameter and splines but what else? Thanks.

I like your car snowman. Brought back memories of a '72 2dr post Skylark I used to have.

Snowman,
Yes, 4v means 4-barrel.
Well ok, if you don't want to go the turbo route, the other top combo that Tom Lowe plans to dyno is a 250 with a barely-streetable cam and Webers. I do mean streetable, I ran a cam that wild in my old 2-liter Pinto of all things. It was liveable, at least in Northern CA. Not sure how it would be on a sub-zero NW Illinois morning though.

So I gonkulated the cam+Webers combo in your car, with a 4.56 gear and the T-5:
14.32 at 95.5.
Once again it will be a close race, but you'll need the 4.56 gear and T-5. And, I bet the Weber setup would be as pricey as a turbo, since you have to build the 250 either way - to survive the turbo pressure, or to survive the 6500rpm shift points of the Weber combo. It is just hard to get a 250 to keep up with a 400 Stage 1 in the same car body!

haha alright. I hear ya. What would be the advantage of 3 singles over a 4 barrel? It seems like the 4 barrel's secondaries would help the most with performance but then again this is my first car and I can't exactly compare my experience... And you are right. It would be INSANELY expensive.

LOL, there is NO way I can run a 4.56 in a daily driver. and I actually doubt it has a 4.10 in it. But when I replace the rear end and put a posi in, it will probably be a 3.83 or a 3.50something. But the BW T-5 having OD will help. But I really need those questions I asked in my last post about the T-5 answered so I'll know how expensive it'll be and if it'll even be feasible to put it in there.

My plan right now is for my dad and I to go to the GS Nationals in middle May and see if they'll let me run the 1/4 mile there. I checked around all of the tracks near memphis and all of the strips near here that are within 2 hours are ALL 1/8 miles. So hopefully I get that bone-stock run in and posted on here. Then in maybe 2 years right before I go off to college. I'll go to the GS Nationals again with my dad and run it again after all of the upgrades.

One thing I have found with T5's and performance. They are weak. The good stock ones, behind Camaro V8's are rated at around 300 ft lbs tq.
I have used one in a Chevelle from a mustang GT (also broke it with a V8) , but my chevelle had bucket seats. Shifter came up in almost the exact proper location. A muncie will put it in the perfect location. My dad has a 66 chevelle that came with a 4 speed muncie and bench seat, so the shifters for bench seat were available.

Just look & see all those 5.0 Rustangs had T-5 trans,they can take a bit of abuse from a V-8 302.

Sure they all will break after you keep beating on them.
There are world class T5's which are better.

But honestly,your 250 6 will not put a beating on the T5 like those Fox body mustang guys put them through.

They (fox body mustangs) have what you call recipe suspensions,put a few upgrades of rear suspension upgrades ,slicks,or sticky DR's & the run 1.6 60 ft times,which is pretty hard on those T-5's but they still lasted a short while.

Like I stated earlier,,,I don't think you will put a beating on a T5 trans like those mustangs do,,,,unless you get serious about drag racing your car,that would be a different story .

For an everyday driver & reasonable price,(I assume you dont have an endless bank account) The T5 is a very good trans,,,but if you beat on them,run slicks & side step the clutch @ 5000 RPM,just like almost any trans, they will eventually break.

A T5 from a V-8 application will be a better choice.

I used a couple T50 5 speed trans from a Chevy Monza(4 ,cyl models),super low 1st gear,like .95 OD in my Camaro 250 6 ,they would have lasted a long time if I did not beat on them.

Bought those from junkyard cars. Made them look like a 3 speed(hung a couple linkage rods on the outside) so I got them for a lower price $75 ,this was many years ago.

This was also the time I got the best mileage w/those tranys,21-22 MPG.
W/the T-5 you can cut @ weld & reposition a shifter handle where you need it. Because the shifter location will be a bit further back than w/a muncie.
With todays gas prices, you should get a trans & take advantage of one w/an OD.


MBHD

Now that I look at it. How on EARTH will that huge thing fit into my car? It looks like it is a lot bigger than a saginaw and I don't think there is any way that tranny crossmember is low enough to fit it. What would I need to put it in?

Read all you can find about T5s. There are lots of variations in strength, ratios, OD ratios, clutch splines, shifter locations, bolt patterns,and opinions about how well they work. At this point I have a built one from an S10 in my '53 Chevy pickup with a strong 270 GMC in front of it. I have abused it and it is still there. The rear gears are 3.55s. First gear is a bit too low and it is a tossup as to which gear to take off in. The shifter is so sloppy that shifting back into first instead of third from second is a worry. The OD in it is the lower of the choices. I have the stuff to fix the shifter and I have a 3.08 rear end to try. My son's '54 Stude wagon Has a WC T5 behind a supercharged built 300" Stude V8 and 4.27 rear end. It made several round trips from Nevada to Texas pulling a U-Haul at 70-80 all day and got around 17mpg. The rear end became the weak link. Go to out Tech Tips and read the T5 Page for starters. There is a lot on Stovebolt and the HAMB. Beater

Agreed, look over in our "Tech tips" there's an entire section along with a link or two. Not as hard as it seems.

Would a 500cfm edelbrock be too big for my 250 with headers and this cam? http://www.summitracing.com/parts/CCA-K61-246-4/ Do you guys have any suggestions for another cam?

That is a big cam. It will have a nasty idle. I think their RPM range is off (1500-5500) Bet it is more like 2200-6500.

The 500 will be OK but a smaller 4 bbl will work better. Maybe a 390 holley.

Maybe pick a cam with .050 duration of around 210-215 and lift under .525 . Tom

X2 ,that cam is pretty stout for your engine. Too much IMO.

At the most 218 @ .050 w/Rhoads lifters,or a solid tappet (but you'll need to adjust the valves once in a while )

I used a few sets of Rhoads lifters w/a few Clifford cams,never liked there cams BTW.
The Rhoads sounds cool like solid tappet cams, a little loud,but to each his own.

I switched to solid cams strictly for better performance over hyd cams & they definately did that.
I don't mind adjusting the lash once in a while.

I tried a few quadrajet carbs ,Spreadbore style,never could get it to run that great,but I am pretty sure if you could get one sorted out they could run pretty good a long w/decent mileage.
They ran those carbs (Stock)on the Ponitac L6 230 & 250 engines w/10.5:1 compression (off the top of my head)

I will say when I tried the Quadrajet carb w/the Clifford intake manifold the carb did not get a strong signal to work that great,it was however a little bit more driveable/streetable w/the Offy intake.

The factory Sprint 215 HP? Pontiac 4bbl intake resembles (SP) the Clifford intake. So I think that GM had the Quadrajet figured out for the Pontiac L6 230 & 250.

MBHD

Alright. After reading around a bit and looking at my options... I am COMPLETELY lost. I never thought about a lot of the factors in choosing a cam. Can someone break down the important parts of a cam and what type of lifters, pushrods, springs, etc. to get? Like sounds and performance and everything.

By "nasty" do you mean unstable or cool sounding or what? I always seem terms like that referring to the idle but I don't know if it is a good or bad thing.

What type of stuff would I have to do to the 194 head to use a nice performance cam?

Thanks

Carb, sure. You can run that even with the stock cam.
I am doing it right now with a 500cfm Autlite carb. A little big but the cam and other stuff will grow your engine into it.

That cam is a little wild, but if you can still ponder that T5+4.56 rear it will work. (That rear is not so bad - with a mild 0.75 overdrive of the T5, you have effectively a 3.42 gear which is liveable even on the freeway. And, with that cam, your engine won't be happy cruising much under 3000 anyway.

Here is what the Gonkulator says about your Buick, stock 250, Clifford and 500 Edel, Headers, Stock cam, T5, 4.56:
Torq 219 at 3000
Powr 168 at 4700
16.72 at 80.5

Now add the Comp 230-230 cam:
Torq 231 at 4000
Powr 218 at 5500
15.81 at 86.1

Yup, it works, at least the Gonkulator thinks so.
I'd go thru the engine first though since I was shifting the Gonkulator at 5800, pretty high for a tired original 250.
Next up would be a fancy cylinder head.

When you say 500cfm on your Autolite, is it a 4 barrel? Also, what would be the advantage of a 4 barrel over a 2 barrel in a 250? It seems like whenever you opened up the secondaries, it would just drown it. But you think after everything and the cam, a 500cfm 4 barrel wouldn't drown it if I floored it?

Snowman,
Yes the 500cfm Autolite I'm talking about is a 4-barrel, a "1.12" Autolite 4100 used from 1958-1967 or so. Vacuum secondary, like the 390 Holley. 500 Edel "air valve" secondary is similar in that it opens only when it wants to, not just because you floor it.

Advantages of a 2-barrel (the kind where both barrels open at once) for the street are:
1. They are cheap.
2. They are simple.
3. They have fewer idle circuits than some 4 barrels so can be better on smog.
4. They work great on 3x2v multi-carb setups.
5. They make great parts carbs for 4-barrels.
6. Good door stops, too.
7. They are also great if a 2-barrel intake is all you have.
I can't think of any other advantages of them.

Now, a PROGRESSIVE 2-barrel, like the 5200 Holley/Weber, the ex-Pinto etc. carb, is a good street setup. Only one barrel is used for cruising, but then when you floor it, both barrels open when you ask them to (it is a mechanical secondary).

Like any mechanical secondary progressive carbs (2-barrel or 4-barrel), sure you can bog the car by opening all the barrels at once. So you just have to ease into them on launch. The advantage is, on shifting a stick car, when you floor it again, they all open NOW, not fractions of a second later which could cost you the race.

Note the other guys' responses on that 230-230 cam - 'nasty' means if you floor it much below 3000, it will quit - literally. That nasty. At idle it will be tolerable on warm summer days with well-behaved carburetors, but 'nasty' when not warmed up. Nasty there means so rough it will load up in the wintertime and flood at some of those long, long traffic lights, stall, and you won't be able to start it again for maybe hours. It will sound really "Phat", but not very liveable. It will run like a big block v8 though, in that you'll be stopping for gas every 100 miles or less.

I just Gonk'd that cam for you because you will need to get pretty "nasty" with that 250 to keep up with your dad's Stage 1 car, else use a hair dryer (turbo). Or "NOSS".

Yup, you have a lot of choices to make, easiest would be to be happy even if you don't run 14s like that Stage 1 car. One of the best times I had in high school was helping to get a friend's 326-2v / powerglide Tempest from the high-17s to the mid-17s by adding a 4v. It still wasn't a "money winner" on Telegraph Rd back in Michigan, but we were happy with what we did, that's all that matters.

Snowman,
You have alot of decisions to make, but, unless your indendently wealthy, I think you first need to determine what's your budget and then determine where to get the most bang for your buck.
p.s. - I think that is alot of money for a cam kit. I purchased my entire engine kit that included a Comp Cam and Comp Cam lifters for $415. The kit included all name brand parts - Cloyes, Durabond, Clevite, Sealed power, Hastings. Shop around before you give up your money. Spend it on a set of Langdon Headers or some head work instead.

Again - good luck and remember

well now you've made me want a dual two barrel setup. Are there any good intakes for that setup besides a offy 5414 (or maybe that was a triple...)? I looked at clifford but didn't see one.

And as for the carbs... do you guys have suggestions? My price limit for each would be maybe $125 used for each. I found an edel 500cfm for $98 used but how would you compare that the edle 500cfm + 4 barrel intake vs. dual 2 barrels + intake in the categories of price and performance. (I know I'm kind of backtracking on my other questions but in this particular comparison, what do you think?).

What would you guys suggest for a cam since apparently I don't really know how to pick one? I was looking at comp cams but now I'm kind of lost as to which to choose. http://www.compperformancegroupstores.co...e=CHEV466Cam194

And by the way, for those of you that have headers on a 250 or the like, how did you get your headers to go out the back? The only headers that I've found that would fit a non-truck 250 have stopped at weird angles that would be nearly impossible for me to find a way to weld pipes out the back. Would these http://www.cliffordperformance.net/Merch...egory_Code=C250 be too long for a car or would it not make a difference whether it was a car or truck? because something like this http://www.cliffordperformance.net/Merch...egory_Code=C250 would be hard to weld up an exhaust system because its angles.

Thanks

I hear what you are saying. I've already thought about this a good bit but as of now I have a little over $150 and I've been looking around on craigslist and ebay for good prices. My plan as of now is headers/exhaust system -> intake/carb -> cam/lifters/springs -> other stuff (with transmission somewhere in there which'll probably be a christmas present or something) -> other engine stuff -> have a soda -> watch tv -> body work. Alright the last couple of things were a joke but I'm not particularly concerned with how it looks right now.

The hotrod headers will fit your chassis. I have used them in a chevelle. It is hard to keep them sealed up.

I recomend a small 4 bbl( 390 holley list 8007) and a Comp 260 cam. That is a start and then work on the head. That is where you can gain some good power too. Tom

by hotrod headers, do you mean the truck headers? http://www.cliffordperformance.net/Merch...egory_Code=C250 because I know the other ones will work but it's a matter of getting pipes to come up to the right place but the truck headers are already at the bottom which is much more convenient.

And why do you reccommend a 4 barrel over 2 2-barrel setup?

What kind of stuff could I do to the head? Get a 194, install lumps, and...

Send your 194 cylinder head (when you get one) to Twisted6 , AKA Larry, or Sissells, Mike K, to properly unshroud the larger intake valve you would install into your 194 small chamber cyl head.

Do you want a solid camshaft or a hyd camshaft?

MBHD

What do you mean unshroud? and I'm not sure what the difference is but my first instinct says solid. And I was thinking about getting the 268 comp cam.

whenever you opened up the secondaries, it would just drown it

Backwards.
Carburetors don't regulate fuel, they regulate air.
Engine demand controls the fuel.

So for a clear cut answer... If I ran...

Maybe triple single barrel intake - http://www.summitracing.com/parts/OFY-5414/
or
Maybe dual 2 barrel intake - Are there any?

3 singles or 2 barrel(s) - Any ideas on a kind or CFM?

268 Grind Cam - http://www.summitracing.com/parts/CCA-K61-244-4/
Headers - http://www.cliffordperformance.net/Merch...egory_Code=C250 (would these fit?)
Heads - Ported and polished
HEI Distributor

Would all of those work together and make some kick ass power? :-) Thanks

We are always tempted, especially at the beginning, when we are hoping to make more horsepower, to assume that if some modification is good, more would be even better: "If some's good, more's better!" It is not always so.

You have received some wise counsel from experienced hands on this forum. Start with a small four-barrel carburetor, a relatively mild camshaft, and headers. Get that combination to run right, and you will see an immediate increase in power. Then, looking for more power, you can work on the head -- porting, lumps, larger valves, more compression, whatever. Once you have all of that working together, then you might be able to use a more radical camshaft and more carburetion. It is far better to make progress in stages -- and much less expensive -- than to go all-out at the beginning.

All of these things cost money and time, and the "more" is also more complicated and more difficult to tune and drive in traffic. If you try to have "more" before you have mastered "some," then after a few misadventures on the side of the road you are quite likely to pull the whole thing out and buy a "350" from the salvage yard. That's where many of us have accumulated some of our less expensive parts for inlines, from folk whose "want" exceeds their knowledge and their "wherewith."

You can likely make some serious power with the combination that you have suggested. You will do well to get there in stages, learning and paying as you go. We hope that you do good and do it well. It is hard to watch someone learn the hard way.

God's Peace to you.

d
Inliner #1450

Haha thanks. It's just that I'm going off to college in a few years and I'm not going to have hardly any tools after then for a long time (probably about 6 years since I'm planning on getting a masters in computer engineering or computer science). So I just want to get everything I can done so that I can be done with the engine and mechanical stuff when I leave for college (at least til I graduate and get my own tool collection started). So I don't have a whole lot more questions but I'll probably think up some soon. I just got a fair amount of money from selling some iPhone parts so I'll try to buy Santucci's book. Thanks for all of your help guys! :-)

Snowman;

I have a 1971 Chevy Nova that is very similar in size to your Special. Take a look at the links at the bottom of my sig and check out the pictures of my car build. You can see what the 4bbl and manifold look like. Also see how you could do the exhaust from the Langdon's dual cast iron headers. Mine is a 250 as well with a Saginaw 4 speed that has a 3.11:1 1st gear.

When you say that, do you mean that it would bone-stock or after all these upgrades? Because I can just run on the primaries until I get all of the other stuff

That cam is as big you could go w/what you are looking for,,,but,,,, you need Rhoads lifters to use that cam.
Or go w/a cam of about 210-212 degress duration @ .050,, & not need Rhoads lifters.
Comp cams will grind any specs you want for a cam,just another thought. Like a cam w/a lobe separation of 112 degrees instead of 110,,, to smooth out the idle,a bit more streetable & help bottom end power a tad.

Honestly,I would use the Langdon cast iron header manifolds, less headache,should not get leaks,,will last a lot longer & most likely would not be down much on power as compared to tubular headers.
An Edelbrock 500 CFM 4 bbl carb,less problems,as compared to Holleys. Plus Edlebrock sell a complete tunning kit for that carb also. Metering rods,jets, springs ,etc.

Cyl head,as I stated earlier,& a must get if possible ,, the small chamber 194 head,to raise compression, & lumps & larger valves.
HEI is good.
For the most part,the polishing on cylinder heads is just mainly for cosmetic reasons.

As stated earlier ,you can do these upgrades in stages,,, easier on the wallet.

MBHD

Now here's what I don't understand... If these http://www.stoveboltengineco.com/acartpro/product.asp?productid=171 are the headers you are talking about, how on EARTH am I going to get pipes welded up to go out the back? Because then I would need to get a pipe that is bent at like 63.524692 degrees whereas those truck headers are already pre-bent from the factory and I would just weld up 45 degree angles easily for the under the car stuff.

pull the whole thing out and buy a "350" from the salvage yard

This happens way too frequently: "buyer's remorse", when they look at the cost per HP and realize what a bargain even a used V8 is.
You should only be considering this if you understand that this is not a cost-effective way to make the car fast (which is nitrous), but it's an excellent way to make it interesting, memorable, fun, and educational. You learn nothing by putting in a crate motor.
I'm working on a 1937 Harley engine, which will probably never make more than 70 HP (original is about 38) instead of a shovelhead, blah because it hasn't been done and I'm inventing it as I go along.

Well I don't really want a V8. I want to keep the car original because I'm kind of sick of how people take some crap car, stick a huge engine in it and think it's cool... because it's not. What's cool is making the best of what you have. I was given a 69 Buick Special Deluxe with a Chevy 250 Straight six... and I'm not going to stick a 455 in it and get a new paint job and think I'm the cat's pajamas. I'm going to keep it original (unless the block gets destroyed somehow) and make the best of what I have. As long as I'm happy, then it's all good. And it is also an incredibly rare combo (250 and 3 in the tree stick (which I'll make a 4 or 5 speed)). My dad has been messing around with 68/69 Buicks forever and he has never seen either one of those things in any of the cars he has seen and he's owned 5 or 6 of them (all 350s or 400s). And it's just going to be fun to take people for a fun ride and then pop the hood and show em what's been throwing em around. Like I said, I'm going to make the best of what I have and I'm going to have a hell of a good time doing it.