Alrite 273 guys heres some first hand info & results on the head gasket dia debate. I had comitic make me some .030 mls gaskets in 3.700 dia & thet fit the bore perfectly! heres the bad part the cyl head chamber is a little bigger than the bore so there is now some exposed steel gasket not doen anything & i figured it wouldnt be an issue...... Wrong! ive had her runnen about a total of 2 weeks ish & yesterday she started to randomly make a god awfull tick/konck until it droped #5 all together. Pulled spark plug to see strap bent over on it so i got the bore scope to see wtf happened! & found 3 small chunks of thin beat up steel in the hole that im assumeing is the "out in the open" part of the head gasket! See pic. got those chunks out & she runs like she did before!:cheers: i got sooooooo dam lucky it didnt trash the bore or valves just roughed up the top of the piston a little. soooo i guess match the gasket to the head from now on guys just a heads up!