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Topic: Compression ratio

in Forum: C3 Engines

Compression ratio

Posted: 12/8/20 4:36pm Message 1 of 5
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Cana, VA - USA
Joined: 7/3/2016
Posts: 372
Vette(s): 1975 Stingray 71 350 engine Flat top pistons Sniper fuel injection Hyperspark ignition Vintage Air air conditioning Borgeson power steering box

Does anyone know what the compression ratio may be for a 350 engine bored .030 over with flat-top pistons?

The heads are 76cc and the head gasket compressed thickness is .041.

 

 




   

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Re: Compression ratio

Posted: 12/8/20 5:33pm Message 2 of 5
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Equinunk, PA - USA
Joined: 10/31/2007
Posts: 2465
Vette(s): 1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.

Close to 9.3 to 1. Depends on the cam too.




Re: Compression ratio

Posted: 12/8/20 7:49pm Message 3 of 5
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Overland Park, KS - USA
Joined: 7/9/2003
Posts: 914
Vette(s): 1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day. 2023 Accelerate Yellow HTC Stingray

A stock '73 L-82 had 76 cc. heads, steel head gasket, and flat top pistons with a slight valve relief and was rated 9.0 CR.




1973 L-82 4 spd

Re: Compression ratio

Posted: 3/5/21 1:32pm Message 4 of 5
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Troutdale, OR - USA
Joined: 3/4/2021
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Vette(s): 1968 Roadster - 327cid 350 hp - Both Tops - My dad was the original owner, and now, I'm in the process of restoring it to like new condition.

Here is a great compression ratio calculator. 

Compression Ratio Calculator

I'm rebuilding my 1968 327, and the calculator says that I'm at 9.74:1...just right for 350hp on premium pump gas.




Re: Compression ratio

Posted: 3/5/21 5:07pm Message 5 of 5
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Cana, VA - USA
Joined: 7/3/2016
Posts: 372
Vette(s): 1975 Stingray 71 350 engine Flat top pistons Sniper fuel injection Hyperspark ignition Vintage Air air conditioning Borgeson power steering box
Rich Wahne said:

Here is a great compression ratio calculator. 

Compression Ratio Calculator

I'm rebuilding my 1968 327, and the calculator says that I'm at 9.74:1...just right for 350hp on premium pump gas.


Thanks!  This is a handy tool.  Mine comes out to 9.62 CR.

I always liked the 327.  When I was 17 I bought a 360 HP crate engine from GM for my '62 Chevy II.  That was one high-revving powerful engine.  Wish I still had both of those!




   

in Forum: C3 Engines


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