Good Morning,

I have an 83mm engine bore. Could I run an 84mm head gasket?

I know you don't want the head gasket diameter to be smaller than the bore, but is there any harm in the head gasket diameter being bigger?

Only things I could think of is maybe carbon build up on the block deck and head where the gap would be. I also dont know if it would mess with the combustion having that little extra gap there.

I never checked or noticed myself, but I heard the OEM headgaske is 81.5mm for a b series engine that has a 81mm bore. So if its ok from Honda then maybe there is nothing to worry about.

Any thoughts are appreciated.

 

get an 83mm gasket from golden eagle.

 

hi.

You can use a gasket which is larger than the bore in points but not a whole number.... like it can be 83.5mm max if your engine bore is 83mm but if you use 84mm then the effects under high temperature could be fatal and might result in the gasket to leak again.

 

if however you use 82.5mm or smaller gasket for a 83mm engine bore.. then the upper part of the piston might get in contact with the gasket which can result in a knocking noise and it wouldn't be pretty.

 

Thanks for the information. Could you elaborate more as to why the high temps could affect a larger gasket and be fatal?

 

Oversizing and undersizing a head gasket produces a pronounced edge that stick out, or creates a small cavity in the gasket area. Extreme pressure from combustion will allow the gasket to potentially blow out sooner than a gasket that is near flush.

A larger gasket is obviously a problem because of possible piston interference, and may actually heat the exposed part of the gasket enough to flash melt.