1970's Chevy NASCAR engine
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1970's Chevy NASCAR engine
I was told that after NASCAR went to a 358 cube rule in 1974, Chevy used smaller cubic inch versions of the big block and not the SBC. Is there any truth to this?
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Re: 1970's Chevy NASCAR engine
There was a driver named Greg Sacks who drove a Winston Cup Car at Daytona for Gary Nelson, Gary may not have owned the car but he was the brains behind the engine combination. Greg won that race (do not remember the exact year) i am guessing in the late 70's. I was told the engine was a de stroked Big Block, the reason of course was the B.B.C. cylinder head would flow more than the small block head at that time. Needless to say that was put to rest quickly, but that kind of thinking was part of what made NASCAR so interesting for gear heads at heart. Maybe some of the older guys who were in NASCAR back then can verify if this was true ? Mark H.
Re: 1970's Chevy NASCAR engine
SO the NASCAR 358 maximum engine size did not necessarily mean small blocks only?
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Re: 1970's Chevy NASCAR engine
A stock bore 396 was 4.094". a safe assume would be bored plus .030". it would take a 3.345" stroke to be 357.51 C.I. would be a RPM er in those days, pray the pieces stay together LOL . Mark H.
Re: 1970's Chevy NASCAR engine
Back before the strict 358" rule, NASCAR tried several wheelbase, weight, carburetion and cubic inch variables to handicap the hemi/semi-hemi/shotgun Boss heads. IIRC. I saw a 305" Superbird, a 396" Chevelle, 350" Chevelle, 405" and 397" hemi and a bunch of other weird shit. Having the factories trying to guess what NASCAR would ban or allow next was making everyone crazy, so that's when the 358" rule was initiated.
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Re: 1970's Chevy NASCAR engine
I think Chevrolets first real serious attempt at the NASCAR small block was the aluminum 18 degree head. Around 1980.
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Re: 1970's Chevy NASCAR engine
To me the biggest advancement in the GM camp was the introduction of the SB2 cylinder head with the totally new Intake port layout. Intake flow increased appx. 50 CFM over 18 degree heads. Mark H.
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Re: 1970's Chevy NASCAR engine
The first "downsize" from 427ci was 366. Bill Thomas Race cars out here had two 366( short deck , NOT truck) Nascar engines on pallets. Came right from Chevrolet Engineering. Ford also tested 366CI big and small block engines eventually going with the 351C based engine. Big block engines were "rules out" in '74 when Nascar began "dictating" what could and could not be used.
Re: 1970's Chevy NASCAR engine
I was doing a lot of cylinder head/manifold work for the Nascar teams during this time (all small blocks) and I'm pretty sure Sacks won the July race in '85 while driving for Digard. Nelson was the crew chief and they developed an aero/chassis package for that race that was outstanding.swampbuggy wrote: ↑Sat May 02, 2020 10:20 pm There was a driver named Greg Sacks who drove a Winston Cup Car at Daytona for Gary Nelson, Gary may not have owned the car but he was the brains behind the engine combination. Greg won that race (do not remember the exact year) i am guessing in the late 70's. I was told the engine was a de stroked Big Block, the reason of course was the B.B.C. cylinder head would flow more than the small block head at that time. Needless to say that was put to rest quickly, but that kind of thinking was part of what made NASCAR so interesting for gear heads at heart. Maybe some of the older guys who were in NASCAR back then can verify if this was true ? Mark H.
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Re: 1970's Chevy NASCAR engine
A good friend of mine ( lost him last year RIP Dave ) Dave Vaseleniuck was very involved in the first ever 358 run in nascar. Told me many stories about developing it. He did all of Davy Allison engines, development for Roger Penske, etc..
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Re: 1970's Chevy NASCAR engine
AFAIK, At the Atlanta 500, nascar mandated the 390cfm carb on all big blocks, effectively ending any competitive big block engines. There were a few incidents of big blocks still running after that, but AFAIK, none won. I was just a kid back then, but I did remember Richard Petty protesting a big block powered car passing him and saying, "there's no way that a big block could have passed me like that." Nascar inspected the car post race and found a nitrous bottle hidden under the dash. I don't remember whose car it was though.
That was the first time that I personally had heard of nitrous oxide being used in competition (although Smokey claimed that it "cleaned up the air a bit.")
That was the first time that I personally had heard of nitrous oxide being used in competition (although Smokey claimed that it "cleaned up the air a bit.")