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Joined: Jan 2004
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Roar Offline OP
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I'm restorodding a 39 GMC track roadster I dug out of a backyard and need to do something to the small port head I have, anyone been there done that??
cheers;
Roar


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I'm not sure how serious the work I did can be considered but I did warm up a small port 270 head with decent results. You can click on the photo for a few more details.



I would say the results are pretty decent compared to stock, but not what I would call really aggressive. The motor pulls hard from idle up to about 4000 rpm. A lot better than the stock 228 did that I pulled out.

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Ken, neat looking setup.

Roar, how hot are you trying for? The small port head should do anything you want if it's a street engine. If it's a race piece there are too many variables without more info on your combination and what rules constraints you are operating under.

The track roadster sounds intersting, do you have any pictures?


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I think a stock 302 head fitted with 1.94/1.60 valves would best anything you could do with the small port heads.

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Very nice work work Ken! The valves seem just right for that chamber looks like you've done what can be done for that little head. What are those nice slugs? My 228 has big pop ups (stock)? so how much did you chop the head and block to get decent compression?
I'm looking at 1.94's from chevys.
This is a OLD car build probably after WW2 from a 1/2 ton 39 GMC P/u Eric, I'm redoing it as it was originally using only the old bits so no aeroquip--tho it was available surplus come to think of it. In those times there weren't very many standards but each track often had their own specs.
This car seems to have followed the 'junk class' rules: 270cu.in. a certain cockpit size, wheelbase, etc. It has a 34 Ford P/u grille surround and a pointy tail.
I don't plan to run it in the circle tracks but may be able to run at the Buttonwillow raceway course not too far away.
To me it's just doing a piece of what I like to: a recreation of a modified sports or racing car.
I do all my own work with exception of the heavy machining--have none of that serious machinery. This fits with the way cars were built then, most weren't works of art.
I'd really love running downdraft piping through the top of the head like Holbay did on the English Ford for Formula juniors. To that extent, I'd like to saw a damaged head up to see where the iron is.
Ive been building racing engines for a long time so this is the only problem I see with the GMC engine.
I'll keep the list posted as I go along.
cheers;
Roar


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Roar - the pistons are from J&E. The deck and heads were barely skimmed to clean them up. The smaller chamber 270 head with these pistons make about 9.5:1 compression.

I recently picked up a tri-carb intake and I am going to see what kind of difference that makes.

I would like to also try a big port head in the future - but I don't want to screw up the compression ratio in doing so.

Right now the motor has very good road manners - as a friend said "the exhaust makes the motor have a sound of authority" . . . LOL

It can pull my basically stock 1950 pickup up to 95 with a little effort in 3rd (direct drive) with a 3.73 rearend, not bad considering that the truck has the aerodynamics of a brick.


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