Quote Originally Posted by jim_in_dorris View Post
Good to know. I am concerned that 53cc combustion chambers with the flattop pistons will put me up over 10:1 compression, not exactly sure I could tune it properly. The 191 heads will yield 9:1, something that seems safer on an older motor with miles on it.
I bet if you put the numbers down correctly it would only be 9.5:1 with the 53cc heads. My 1983 305 was about 10.2:1 from the factory. Flat top pistons with 6cc worth of valve reliefs, .025" down the bore, .020" thick steel shim head gasket and the 53cc heads. Pulled a couple of 85-86 305s with the same heads that had dished pistons in them.