i just picked up a set of 305 heads for my 355...i know they won't flow any better, but i was hoping the compression gain would make some power. can someone help me figure out what my CR would be with a 355 flat tops and (what i believe to be) 58cc combustion chambers. i looked on the internet for a compression ratio calculator, but couldn't find one. thanks guys.
-Jay

There are a couple linked in my sig.

Pat-
thanks for the page, but theres a problem. i haven't ever dug for enough into the top end to know the piston to deck clearance, compressed gasket thickness, or the head gasket bore...i'm guessing that the head gasket bore is matched to the cylinder bore, but im not sure. could you give me a ballpark estimate of how thick the head gasket is? thanks again.
-Jay

This might help (http://members.uia.net/pkelley2/DCR_FAQ.html). It is the DCR FAQ and answers your questions. For a flat top piston, 6cc is pretty common but they could be something else.

Also, it is possible to get the head gasket thickness without pulling a head. If you look closely around the head, you can see the gasket peeking out in places. You may be able to measure it with a dial caliper. If not, you might be able to tell if it is a comp or shim gasket.

stick a feeler guage in the head to block gap to get an idea of what gasket is in there, there should be gap visable at the end of the head