Chevy Nova Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
1,642 Posts
Discussion Starter #1
I need a compression ratio estimate. I have a 30 over block with trw flat top pistons, and 64cc chamber heads and a 400 crank roughly what compression ratio would that give me? thanks
 

·
Registered
Joined
·
3,859 Posts
What size bore?

My 406 with flat tops, 74.5 cc heads comes out at 10.5 to 1 but I am running a really big solid roller so pump gas is not going to be a problem.
 

·
Registered
Joined
·
1,642 Posts
Discussion Starter #4
30 over stock 350 bore whatever that would be :rolleyes: Ill be running alluminum heads so it should help with heat disipation and detonation.
 

·
Registered
Joined
·
3,859 Posts
400 crank will be well over that 10 to 1 of your 350 with the same heads.
 

·
Registered
Joined
·
5,781 Posts
30 over stock 350 bore whatever that would be :rolleyes: Ill be running alluminum heads so it should help with heat disipation and detonation.
http://www.csgnetwork.com/compcalc.html

A 350 had a 4.000" bore. You have a 383, which is a +.030" 350 with a 3.75" stroke crank. Typical Mr. Gasket steel shim head gasket is probably .015-018" and I have no idea what cc to take off for valve reliefs. I just put -4cc in there. Also no idea about your motor's piston-to-deck. Just random guess and it is around 11.4

 

·
Registered
Joined
·
1,642 Posts
Discussion Starter #9
cool thanks guys I was hoping to be in the 11's or 12's
 

·
Registered
Joined
·
508 Posts
its going to be right around 11-1 depending on your gasket. and if you have a two valve relief or four. but either way it will be close to that. no more than 11.4-1 at most.
 
1 - 12 of 12 Posts
Top