Thinner head gasket with cam

[racerguy]

Hey everyone
Im running a 305 with comp cams xe268. It runs great by the way. The motor has flat top pistons, and stock, ported heads. Ive been thinking about a thinner head gasket to boost compression. Should I be concerned about the valves hitting the pistons?

[Doober]

If the block is stock the pistons are probably close to .025 in the hole, a .015 compressed gasket should be fine (stock replacements are typically around .040").

[GreaseDog]

Just be aware that running a .015 shim gasket it will rely more one the block and head mating surfaces to be more flat and true that a .040 gasket will. I'm during here looking at a 120k 350 that a set of Fel Pro 1094s didn't live 10k on. Deck surfaces were impeccably cleaned before they were installed, but just clean wasn't good enough.

[racerguy]

great info. thanks guys. my main concern was whether or not the valves will hit the pistons. also thank you for bringing the deck surface topic into play. I will keep that in mind when making the modification.

[racerguy]

ok so i have one more question. I guess the word "shim" just doesnt fit right. Is the shim gasket actually a gasket? Or is it just used as a shim with a regular head gasket? I guess i need to know more about these shim gaskets before i get too excited and mess this thing up.

[GreaseDog]

No, it is not a' shim' so to speak, but it does not compress like a stock replacement' composition' gasket like your standard parts store replacement gasket. That is why it is more picky about surface finish and flatness.

[racerguy]

ohh ok. I get it now. some of the terms used confuse me sometimes. thanks for the info