I am currently looking at Summit's engine rebuild kits in their new catalog. All of these engine kits list the head volume as 64 cc and I have 76 cc heads I know that my ratio will be lower, but by how much? The two kits I am looking at have the following ratio's.
10.9 with 64 cc, what with 76?
12.2 with 64 cc, what with 76?
I need to know because I still plan to use pump gas, and the max around here at the local stations is 94 octane, (Sunoco). Thank you very much

compression depends on more than head cc, like dishes pistons and head gasket thickness. Id say u lose alomost a point of compression going from 64-76cc heads. that Is a very rough estimate though. The less valve relief in the piston that you have, the more change youll see between the head sizes.


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91 RS W/carbed 350, Vortec heads, performer rpm, Comp cams Xtreme energy 280 grind. BFG Drag radials. 3.42 posi,Corvette servoed 700r4, ****ty stock converter
13.24@104