Ok 3.875 pistons
4" stroke
.030 cometic
.510 lift
Is it correct that I need the cc measurements of the headsto calculate my true compression?Heads were milled. I believe my machinest mentioned 77cc's does that sound right?

 

to be sure of compression, it's best to measure deck height and chamber volume...using the onfo you gave my calculator says 10.17 compressiom...that's assuming zero deck height