Headgasket for .020 over.

[91DSMdave]

I have done some research and havent been able to get a comfortable answer. I have a .020 motor i will be putting together. I have read that stock bore is 85mm correct? And .020 over would be 85.5mm? STM's Website says that their cometic tri-layer comes in 85.5 STANDARD bore and .020 over 86mm? Extreme PSI doesnt state overbore. I just want to make sure, being that i read .020 over is 85.5mm and STM says its 86mm. Which should i use? If .020 over is 85.5mm, i would get a better seal and sleep better at night knowing its dead on. Just need to get facts straight

Also have to order rings, so i really need to know

 

[shadow001dsm]

85.5 is what i used

 

[GRAVEDIGGER]

.020" over is 85.5mm..... PERIOD

.040" over would put you at the 86mm, or 86.016 to be exact.

 

[91DSMdave]

So STM has it listed wrong. Bet that's great sure as hell confused me . Thanks guys.