Inliners International Forums General Discussion Hi Performance Grumman Olson Project

Hi Guys,

I've been checking out this site for a couple days now, seems pretty good.

I have an 83 Grumman Olson van (ex-delivery van) with a full aluminum body and a 292 straight six engine. I use the van for work and hauling tools. The motor is stock and possibly rebuilt. My first thought was to swap out the motor for a diesel or a SB 350 but I really like the sound of the motor so I did a search for performance 292 and came across this site.

My short term goal is to increase the power a bit and get some better fuel economy. Then later I would like to strap on a turbo for some good power, but nothing crazy. I don't like to buy things twice so I was hoping for a little direction from some experienced members.

I was thinking my first upgrade should be a Offenhauser intake and a 390 Holly carb. Then second upgrade would be a better flowing muffler. I was thinking about an MSD distributor with vac advance but I don't know the benefit from stock.

From there I would like to vet those bolt on lump things I've seen mentioned as well as some groovy engine covers etc. And finally the turbo, intercooler, BOV and boost retard timing of some sort.

If you don't mind, let me know some suggested parts/part numbers I should use or guidance.


Thanks
Dave

Neat project. I know where one has been sitting for 25 years. It has a 292 of unknown condition. If I buy it I'll probably swap in one of my 300 Fords.

Doesn't Tom Langdon at Stoveblt use a similar one to go to swap meets? Frenchtown, start looking for a P series Ford

Will the 390 Holley carb be a good choice for the stock motor? Will it also do ok if I decide to turbo it?

What about exhaust? It's 2.5" off the manifold then it appears to go to 2" and from the muffler it's 1-7/8" or 1.5" (haven't measured). Would it be fine to run 2.5" right through the muffler to the tip or should I drop to 2" after the muffler? I have read things about other engines needing the smaller exhaust pipe to help draw the exhaust away from the motor (i.e.: too big won't scavenge the exhaust). Regardless I will wrap the first few feet with header wrap to keep the heat down since the floor is aluminum and the exhaust heats it up pretty good.

Thanks for your help/advise.


Dave

Dave,

I'll propose 2 alternative twists...:

1) install TBI EFI on the 292 - all the parts can be had from the wreckers for cheap.

2) do a powertrain swap and install a 4200/4L60E out of a trialblazer. Engines can be had for under $1000 complete. If your near Calgary PNP has 2 in the yard now. The '02 is still intact.

Better fuel economy will be hard to do. You are moving a box. The 2-1/2 inch exhaust will add power and I would do it all the way back. You can get cast dual headers which will help also but make sure you still heat the intake for drivability especially in cold weather. A better flowing intake is a nice idea but you probably lose milage with bigger carb.

This sounds funny but anything you do will be for personal satisfaction. The cost of changes are usually never paid back in economy unless you keep something a long time and you are consistantly a driver who strives for fuel milage....Good Luck

Well "fuel economy" isn't my 100% goal but rather more power. So far in my experience when you give a vehicle more HP I find I don't need to squeeze the throttle are hard to get going. It usually results in a bit better "economy" however in turn I also like to jam on it more because there's more power to play with.

So with that being said, if I'm light on the throttle will a 4 barrel carb give me the same "economy" as I have now (i.e.: stay out of the secondaries) but in turn give me more jam when I ask for it?

I've never owned a carb vehicle so I don't know a thing about changing sizes and how they effect the ride.

Thanks

OK here's my take...I'd use a Clifford intake maniford with a Sean Murphy Induction rochester quadrajet and long tube headers. He's a master with them and the Clifford is a continous tapered intake which make for excellant intake velocity with small primaries. With near 50 cubic inches per cylinder the vauum signal is excellant for 90% of your driving. This is not a new idea as Pontiac used it on its OHC 6. Others have their ideas and this one is what I'd do if it were mine....(carb won't be cheap but what is today)....Good Luck

Jimmy Six,

Thanks for the suggestions. If I go with the Clifford intake would it be good to have the manifold heated with the radiator fluid? Would that eliminate the need for the tube that brings heat off the exhaust manifold up to the air cleaner?

A second question, It seems all of SMI Q-Jet carbs are large CFM units but I am under the impression I should be looking for a 390 or 400 CFM carb, is this correct?

OR is the 4bbl 390 CFM carb going to be too small and force me to always be into the secondaries in order to get anywhere?

I'm very green when it comes to Carbs and their CFMs etc. If i get a carb that is too large will that mean I will over fuel the engine.

Any advice on this stuff would be great.

thanks again.

Dave

Bump

Hey guys, just looking for some advise, I have a 390 carb lined up but I don't want to make the wrong purchase if it's not right for my application, thanks

UNLESS it is the 4cyl version List 6299 I think you can't go wrong with a 390 Holley for performance on the stock or near stock 292. I have clocked many carbs on the Gtech with my 292, the 390 Holley does not always win these "carb shootouts" but it always finishes 1st or right near 1st anyway. My list is 6390. The Holley 390 goes back as far as the 1957 Ford (1st use and in fact the 1st modern Holley 4bbl period). Holley shows List 8007 as the newer 390cfm you might get. Again I would stay away from the List 6299 4cyl carb tho I am not sure what is different inside.

What is the List on the one you are looking at? (On the side of the choke horn)

For performance AND gas mileage I think the Carter/Edelbrock is a good compromise. The 600 Carterbrock also finishes near the top in my carb shootouts even tho it is too big for this near stock 292, the engine doesnt seem to mind. The 500cfm version should be even better with its hi-response primary boosters.

Or the Qjet but I am not a Qjet expert. But the Pontiac OHC 6 ran a Qjet with good results!

Oh man, now you've got me thinking...

I thought too much CFM was bad. If 390 cfm is good for my stock 292 then how is a 600 cfm better?

That line of thinking gets thrown out when it comes to DCOEs

I ran 3 48 MM sidedraft Webers which are too big for my 250, but it was by far,,, the best induction set-up I ever ran for my street car. 4bbls,,,, carbs, yes you can go too big.

MBHD

MBHD, you seem to be quite knowledgable about Webers. How would 3X 40mm work on a near stock 250 engine. I think 45mm is the norm, but with large chokes would the 40mms be sufficient?

40's will work fine & for the most part less $$

You could change the chokes or inlarge them.

If you run those 40's I would think the throttle responce would be instant.

MBHD

inches is inches!
how many of you would run a 390 carb on a 283 (that you just bored .060"?) Well thats a 292 inch v-8. Most guys would run a 600 Holley on a a bored 283, or a 307, or 289 ford, or a 290 AMC. Heck, some guys try to put 750 double pumpers on them
My opinion the only reason for everybody liking (if they really do) a 390 has to be that it aint big enough to cause a problem with 250-292 six cylinder stockers (same can be said for 500 cfm holley 2 bbls). But its your money.
The trip side draft webs can work o.k. because a tuner can easily tune all the circuits on these webers and match it to the particular motor/cam needs-and you have virtually no manifolding losses since they mount nearly directly to the head ports.
Look to the junk yards and find much cheaper carb sources-stay away from smog era carbs. Study the rochester books available (especially doug roe's), check out the Holley and Carter books by SA. A little bit of buckshot lead can be tamped into the various emission passages in the smog carbs to help detox them and make them into some smooth running carb for very small coin.

A word of caution, It is better in all cases to err to the smaller size-you just cant put a trip set of 50mm webs DCOEs on a stocker and expect to tune the stumbles outta it!
your turn Hank

I would suggest you try out a set of DCOEs before you say, "they can work o.k." They are by far ,, the best carb combo you can run on the street, only thing that would be better is running side draft EFI throttle bodies.

I bought my 48 MM Webers w/a Cannon intake used, for a Datsun Z ,240-280 Z inline 6 engine for $200.00

I knew they were not the correct size for my 250 engine, but, heck, for $200 ,I thought I'd give it a try, what would I lose in trying?
The only thing that I definately noticed that the carbs were too big,, was when I could not tell much difference in power between 3/4 thottle & full throttle.
The person was asking about putting 3 40 MM DCOEs, those carbs will be really small when you actually find out the actual size the choke tubes are,,, tiny.

So in short, I would suggest anyone to try or use or beg someone to install a set of 3 DCOE Webers or eqivalant & come back on this board & tell us your opinion as compared to any single 4 bbl carb intake combo you ever used.

I am absolutely positive you would never go back to any single 4 bbl carb/intake.

I never tried out a set of 45 DCOEs ,but my car would have run mid to low 13's really easy w/the 48's, don't think switching to 45's back then would have made my car run in the 12's

You can get away with a lot more carb than actually needed w/side draft carbs as opposed to any single 4 bbl.

The actual CFM my 3 48 MM DCOEs was about 1100 cfm, see how good your single 4 bbl 1100 cfm carb responds.

No contest between the 2 scenarios,Webers hands down, period.
Remember my car has & always will be a street car, w/great street manners always being one of the top prioritys.

I have used & tried many,many 4 bbl carbs, & a few 2bbl carbs,,then I install the set of DCOEs.

I do know they are out the price range for most people, that
s including myself, BTW.
I had to buy a Clifford new intake & nice spherical ball bearing linkage cross shaft, & even though I got my DCOEs for $200, the intake was about $200 & linkage kit another $200.
So all together I still spent about $600, & that was a lot for me back when.

Now, I would never run naturally aspirated since I been into blower & turbocharged engines.

To keep costs down for the average car guy, I would not run DCOEs & a turbo to blow through, A plain 4 BBL & a turbo blowing through would be a much better way of making a lot of power & not needing very pricey DCOEs to do so.
Hope this some how makes some sort of sense to some people.


MBHD

Makes sense to me, Hank. Thanks for the input.

Funny, I did not use blue ink NOR A COMMA. Do you how to read a sentence without a comma?
Exxxcccuuussse me for not bowing the exhaulted throne of the Wop carb.
By the way what is a Datsun L6 motor? I've heard of the L16, L18, L20, L24, L26, L28, motors, but never an L6 motor, what exactly is that, judging by the other sizes, that must be a 600 cc (37cubic inch) engine. Must be a Calif. smog motor, not a federal engine.
What could you loose(or lose)in trying? Ya gotta type what you mean or else how can anyone understand the real meaning of the printed word.
1"=25.4 mm when I went to school back in '63. Therefore 40mm=1.57" is tiny huh? yah compared to the 2.25 (57mm)back barrels of a Q-Jet.
What if my 1000 cfm carb was a Carter Thermoquad with the"tiny" primaries, and vacuum controled secondaries?
As for as which wins "hands down", I firmly doubt either of us has the all knowing wherewithall or any published data to confirm such judgements no period.

bristowbob,
glad to help w/any input of my personal experience.
Also by the quote here:"Makes sense to me, Hank"
You understand what I was saying.

P,N,C,

Thanks for correcting my grammer. Comes in handy.

I guess you do not like my commas,,, or color, or?? O-well,,,,.

The Webers carbs are always listed in MM, not sure why you want it in the standard English measurement?

Just a FYI, my 48 MM blades are 1.90" x 6 blades,,,, not tiny.
Also,,,, the choke tubes I had on my 48 MM DCOEs, about 47MM, paper thin.

Also,,,,,,, 40MM throttle blade itself is not tiny, I am referring to the actual choke tubes, (read my previous post) the choke tubes would be tiny. BTW, that color is green, just a FYI


I do not know everything about DCOEs, not by a long shot, but I do know, you never used them, & that's OK, just passing info here that is true & correct by saying the DCOEs are the better way to go on a "L6" (that means inline 6 for you, just saying) engine as compared to a plain jane single 4bbl , & that's what the subject I am referring to is all about. Not proper names for engines, just a general L6 I would say is sufficient, it's a commonly used term,,,,,, meaning inline 6.

An L6 stands for inline six ,quess you do not know that,, we are talking about using 3 DCOE carbs ,not 2 DCOEs for the L16, or L18, which are L4's, Inline 4 engine.

The L16 & L20 engines you listed is incorrect.
Here are the correct 4 cly engine designations. Just some FYI.
1.1 L13
1.2 L14
1.3 L16
1.4 L16S
1.5 L16T
1.6 L16P
1.7 L18
1.8 L18S
1.9 L18T
1.10 L18P
1.11 L20B
1.12 L22
1.13 LZ (competition)
1.14 LD20/LD20T


Here are the inline 6 eng's correct designations. Just so you know.
2.1 L20/L20A
2.2 L20ET
2.3 L20P
2.4 L23
2.5 L24
2.6 L24E
2.7 L26
2.8 L28
2.9 L28E
2.10 L28ET
2.11 LD28
2.12 L2.9 ~ 3.2
Funny you mention Q-Jet & thermalbog, I have used both of them & again,, no comparision between those 2 carbs & the set of 3 DCOE carbs, Webers are still hands down winner,, I do not need printed data for myself to know what works better,I have driven on the street with them & I raced almost every carb install against friends w/there track/street cars, thats enough proof in my book, maybe not for some, & that's fine, some people need to go through the process themselves to find out first hand even though there are printed catalogs stateing the ultimate power would be achieved by installing side draft carbs such as DCOEs.(Clifford)

I never could afford DCOE carbs, & that is why I did try so many different carbs in the quest for ultimate power for my L6 (paraphrased)as stated in the Clifford catalogs.
I would think that I went above & beyond the average L6 enthusiast of trying out so many different carbs.
All my money (what little I had) & all my free time I had was put into my L6 Camaro,,& that's also w/girlfriends complaining about how much time I spent on my Camaro.
I knew all along that a set of DCOEs would be the best all around power for my L6,, I just could not ever afford a set.

I would have thought Jack Clifford did do some type of testing on DCOEs,or maybe he recieved his info from racers or other published stats on Webers?
Kay Sisslle,Mike Kirby, Mike Barile & many others has used DCOEs with great success,, I think there are probably other carbs available now-a-days & w/a correctly designed intake manifold that can make more power than DCOEs.

But like I said,it's hard to surpass the the driveability, fuel metering of a nice set of DCOEs, other than going w/fuel injection.

*Warning*: This post will include ,mispellings & Typographical errors, & in general not the correct use of the english language.
MBHD

Gosh Hank,
are you always so quick to get defensive? If you would calmly go re-read Preacher No Choir's post, you will find that he was not bad-mouthing Webers, rather his distaste was directed at the 390cfm Holley. After he questioned the reasoning for wanting to use a 390 cfm carb on a 292 when most of us would not think twice about using a 600 cfm carb(or larger)on an equivalently sized Chevy, Ford, or AMC V-8, he then went on to explain why a Weber would work fine in this application. You took exception with the "O.K." semantics and in doing so, completely missed the point of the post.

I, for one, would like to know: when you use an L- designation in front of a number, when does it simply mean an inline configured engine and when does it refer to Datsun's code for a particular engine? Apparently Datsun has/had 26 different engines (according to your list) all whose designation is prefixed with an L. I think we can all agree, that in this isolated instance it is NOT as straight forward as you imply. As I see it, an L6 could indeed be Datsun's 27th engine with an L designation or it could mean an inline 6 cylinder(one of Datsun's 12 in this context). Just so you know.

fasteddie

Now give that man a few gold stars after his name...He can read and write!!!
Hard to sell snakeoil to someone who can read and write!
(uuuh that was supposed to be in PLAID colors)

Now where is that plaid button?

MBHD

Why, it's between the blue one and the green one, of course!

fasteddie

Hey guys,

I haven't had a chance to sit down and relax for a while, but now I'm back. I still have the Grumman, I put 20" chrome wheels on it, LED markers all around, rebuilt the monojet carb along with new cap, rotor, wires, plugs, air cleaner, fuel filter, etc.

The 3 spd turbo 400 tranny is ok but i want lower RPM on the hwy with my 4.10 gears so i bought a 700R4 that needs to go in. Along with 3" suspension drop all the way around.

At this point the van runs good but i'm starting to think about the future. I want more power! Can someone tell me what i can expect to get for performance numbers if I put an Offenhauser intake with a 600 or 650 economy 4bbl carb and a 2.5" exhaust on the stock exhaust manifold.

I like the old school motor and I would love to jazz it up with some aluminum covers from Offenhauser but i don't see the point if i can't achieve some decent power. I can't have this van off the road for more than a weekend because I need it for work so pulling the 292 and doing a major rebuild is not really an option. If I'm going to rebuild a motor i was thinking of a SBC 350 only because it's an easy swap with tons of bolt on goodies available on the market along with cheap prices. But, at the same time "everyone" has a 350 and i like the 292 which would be awesome to keep and tweek; however, to be honest it's a slug to drive and I dont want to waste my money on performance parts if it won't give me good power.

what is the stock 292 HP and what should i expect to see with the mods i mentioned above.

thanks
Dave

If your heart's not in it get the 350 or better yet a big block. You have to want a 292 to make it worth while. If you must swap it get a 4.2. Beater

Dave,
Here is a range for you to think about.
I ran these numbers with the DeuceCoupe Gonkulator computer which is a pretty good estimator. I assumed your big van weighs about 4500 lb, sound right?

Stock 292,
165hp or so:
19.39 at 66.1 1/4 mile seconds and mph
believe it or not this is faster than most of the early powerglide Novas of 62-63.

Stock 292 with 4bbl and headers and duals:
190hp
18.20 at 71.2
Your average v8 car of the 1950s ran about like this.
It is slow but liveable, you dont feel like you have to floor it at every light.
One of my many "rules of thumb" is that if your quarter mile gets a full second faster, it is a Different Car and will feel like it. So this gain fits that rule - as do the next ones.

Built 292, mild cam and work to cylinder head
280hp or so
16.65 at 79.1
My Pinto just out of college ran about like this.
None of the 924 Porches or Beemers would run against me, they knew they would lose.

Not enough?
How bout a TURBO?
I used the computer to "pluck" this turbo 292 out of Tom Lowe's El Camino, here is how it does in your big Van:
469hp
14.79 at 92.5
That will put the hurt to numerous GTO's and 409 Impalas. Not all, but some of them.

So that is a range of what to expect.
The van is HEAVY and pushes a lot of air too.
For example, if that last TURBO setup was in a Caprice instead, same weight but better aero, you'd run
14.15 at 100mph, 7 carlengths faster.

For non-turbo cars on the street, my own rule if, if you want it to run FAST, take the curb weight (4500) and divide by 10.
You need AT LEAST that many cubic inches (ie 454) or you will be fighting it all the way.
You decide!

do yourself a favor and install a cummins 4bt diesel. more torque than a 350 chevy and 25+ mpg. they was retrofits in those vans. there a direct bolt in and up to the th400. i have one myself. call for more info if you like
bob
1-423-384-8938

I have a 4bt in a willys jeep wagon project. Can't wait to get that one on the road. Neat engines.