Grumpy's old pro stock small blocks, hp

[rustang]

I was reading an old article on Grumpy's old pro stock motors circa 1972. HP claimed was 600hp with 331cuin. I was curious what heads were used. Would these have been double humps or some angle plug deal? What kind of rpm did they twist these things to and what kind of tricks were used?

I've seen old Pro Stock AMC heads that they would cut in half and weld one on top of the other, etc. (Wally Booth?) Would the SBC's have been that extensive?

[Stan Weiss]

To be accurate the AMC heads were not cut in half. It took 4 heads to make 2 good heads. One head was cut so the bottom part was larger than the top while the other was cut so the top part was larger than the bottom. The 2 larger pieces were welded together to made the new taller head.

Stan

[DaveMcLain]

Check out Grumpy's old book on the Chevrolet Racing Engine it has a lot of information on those engines and it's still an excellent read. Heads were 292 castings with VERY EXTENSIVE modification especially to the intake side. What's cool is also how many of the parts in the engine are regular production pieces. They were running the engine about 10,000 rpm.

[PackardV8]

I was there in the day and washed parts and pinned the rocker studs for many a short track SBC. Often the roller cam, lifters and valve springs were the only aftermarket internal parts. Still, having gotten used to aftermarket parts, I am continually amazed when I take apart a vintage race engine and see all those spindly stock SBC pieces in there. The Chevrolet engineers were tasked with building the lowest-priced OHV8 and given the directive to use as little iron, steel and aluminum as possible. When they were done, a ready-to-install engine cost Chevrolet about $55 to make. That it came to handle horsepower and RPM incredibly well was a happy accident.

We get used to seeing all the beefy aftermarket parts, but most are just for insurance and longevity. The stock parts would make horsepower for a while.

Speaking of round track, in the early days at Daytona, engine failures were the norm. Oils weren't that good and nobody knew about oil coolers. I've seen races where half the field dropped out with engine failures. None of the stock stuff was ready for 500 miles at full throttle and 6,000 RPMs. Pontiac was the first to figure out how to keep engines together around 1960 and they won most of the banked tracks.

Today, at 9,500 RPMS, failures are so rare, the whole engine program shop team would commit seppuku if they have an engine blow. But there's not a stock part anywhere on the car.

jack vines

[andyf]

Pick up a copy of Grumpy's book, it is a classic. He shows all the tricks they used on those heads. They spent a lot of time eating cast iron dust to make those cars fly.

[BrazilianZ28Camaro]

I was reading an old article on Grumpy's old pro stock motors circa 1972. HP claimed was 600hp with 331cuin.

According this guys , the power is a bit higher.

http://www.carcraft.com/techarticles/cc ... index.html

Only 680 HP @ 9000.

[DaveMcLain]

I went to a thing at the PRI show one year honoring the 40th anniversary of the Small block Chevy engine and I got to meet Jenkins, Yunick, Duntov and others who were involved with the design, development and racing of the engine and it was fascinating. I think that for the most part the original design engineers were amazed at how well their compromises with materials, strength, packaging etc worked out over the years. After all they never imagined or intended the engine to become the most modified engine ever!

I don't think that the car in that story is the real Vega. That car disappeared at the truck stop across from the drag strip in East St Louis.

[bigjoe1]

I saw Jenkins 331 on the dyno at E#delbrock, and it made 665 HP at 8400 RPM


JOE SHERMAN RACINGENGINES

[rally]

It amazing how the stock Chevy parts hold up under those RPM conditions back in those days. And i am old school Chevy drag racer, i built a BB drag race motor with Chevy factory pieces and never had a failure. Same with rods, good conditioning with a shot peen, mag, and good bolts i never lost a factory rod.

[SKeown]

I had a dragster that turned 8K with "pink" rods and stock rockers.

SKeown

[avengerengines]

I saw Jenkins 331 on the dyno at E#delbrock, and it made 665 HP at 8400 RPM


JOE SHERMAN RACINGENGINES

I messed with some modified production back then. We struggled to get near 500 hp with a 331. I said near 500.

[ClassicComp]

Seppuku!!! Jack cars arent your only hobby are they????????

[zums]

the only thing close to "stock " on jenkins small blocks were the blocks and cranks, i use stock very loosely

[rookie]

the only thing close to "stock " on jenkins small blocks were the blocks and cranks, i use stock very loosely

Aluminum rods?

[MrBo]

the only thing close to "stock " on jenkins small blocks were the blocks and cranks, i use stock very loosely

How about that nylon tooth timing gear and silent chain?