Can I turn my 70cc heads into 64cc heads?

[Guest V8Z]

I have a great deal on a set of Edelbrock performer RPM heads but they are 70cc combustion cambers. My 350 block has factory dished pistons and I am under the impression that the smaller the combustion chamber is the more my compression goes up and this make more power. Can I have the heads decked down to lower the cc of the chamber?? Thanks, Paul

[jnjdragracing]

Yes you can. But remember if you take it down to much you are stuck. Then you will have run a thicker head gasket. You can also have your deck cut. I had my 70cc heads cut down to 64 cc. Some of the turbo heads back in the early years were 58cc. Hope this helps.

 

John

 

I have a great deal on a set of Edelbrock performer RPM heads but they are 70cc combustion cambers. My 350 block has factory dished pistons and I am under the impression that the smaller the combustion chamber is the more my compression goes up and this make more power. Can I have the heads decked down to lower the cc of the chamber?? Thanks, Paul

[dr_hunt]

I have a great deal on a set of Edelbrock performer RPM heads but they are 70cc combustion cambers. My 350 block has factory dished pistons and I am under the impression that the smaller the combustion chamber is the more my compression goes up and this make more power. Can I have the heads decked down to lower the cc of the chamber?? Thanks, Paul

 

Yes, you can but the real way to build compression is with piston choice. Besides, with today's gas, high compression isn't the way to go. Cam selection would be critical to optimizing your current setup with the 70cc heads, which are good heads by the way. You'd be suprised what kind of HP you can make on low compression.

[Challenger]

I know the compression is raised when you shave the head but why? If you shave the head your displacement is lowered and you therefore take in less fuel/air. Isnt the intake volume to the stroke ratio the same? Pardon my stupidity.

[dr_hunt]

I know the compression is raised when you shave the head but why? If you shave the head your displacement is lowered and you therefore take in less fuel/air. Isnt the intake volume to the stroke ratio the same? Pardon my stupidity.

 

No, the displacement comes from the piston moving up and down in the cylinder. It squishes the air/fuel mix into the combustion chamber, so a smaller combustion chamber increases compression ratio which is the ratio of the uncompressed volume to the compressed volume.

 

Hope that helps.

[Guest V8Z]

I definitely do not want to change my pistons to flattops, so I should probaly just leave the heads 70cc and pick a good cam to work with the dished pistons? I first wanted to go with the GM ZZ4 heads because they have a 58cc chamber, but after reseacrhing I found that they are not the best of flowing heads. I'm thinking the edelbrock heads will be the best chioce in the long run.

[dr_hunt]

Actually AFR's are the king, but it depends on what you want in the car. You can make good reliable HP with those, it's a better choice than stock, unless your talking GM 18 degree heads.

 

I definitely do not want to change my pistons to flattops, so I should probaly just leave the heads 70cc and pick a good cam to work with the dished pistons? I first wanted to go with the GM ZZ4 heads because they have a 58cc chamber, but after reseacrhing I found that they are not the best of flowing heads. I'm thinking the edelbrock heads will be the best chioce in the long run.