Help! head gaskets

[howard blackburn]

I have recently purchased a Goodwrench LT1 350 com ratio 8.5.1. I have noticed that the head gaskets on this engine are alot thicker than the ones on an L81 engine that I have just stripped. 1981 corvette. If I use the thinner gaskets which are very thin metal type what will the compression ratio go up to on the LT1 engine?

 

[Crimson Thunder]

I don't know about the exact figures because we don't know the exact thickness of the gaskets to do the math,but it probably wouldn't be worth the cost of new gaskets and replacing the torque to yield head bolts.

 

[howard blackburn]

thanks sharkcar going to get micrometer to mesure gaskets

 

[Rodney Gold]

For every 1mm difference in gasket height , with a 4" bore , the difference is 8cc. In all likelyhood , the difference tween gaskets (compressed) is less than .5mm , so in essence , your "gain" is 4-5cc using thinner gaskets.
To put it into perspective , lets say you have 76cc heads , 20cc tween cylinder TDC and heads and a swept volume of 712cc per cyl (5.7l divided by 8) , the comp ratio is
total vol / compressed vol
IE 808/96 = 8.4 :1
Decrease the compressed vol by 5cc and the numbers become 803/91 = 8.8:1
Changing to 64cc heads in this scenario , using stock gasket , will bump you up to 9.5:1

 

[howard blackburn]

thanks rodney

 

[Crimson Thunder]

The heads on your crate motor may already have 64cc heads on it now.I have the older 300 hp crate motor from GMPP and the iron heads on it are 64cc.You may want to run the heads numbers at Mortec.com to make sure.

 

[howard blackburn]

thanks sharky will do that