I dont really know how word this right so I think I will use two questions together.

1. Would using a too thick a head gasket drop my compression by around 60psi ?
(^^^^ I Know that the answer to this is yes ^^^^)

2. What else would cause a consistent 60psi pressure drop across all four cylinders.


Has anyone ever had any problems with using a cometic gasket? I know they are particular about the mating surfaces on the block and head...

For quite some time I've been fighting with what I thought was an overfuelling issues but have learned that low compression combined with normal fuel pressure gives pretty much the same result.

Originally when I rebuilt the engine after getting my head back,I ran a compression test and vaguely remember getting around 75psi per cylinder... I just assumed that having consistent pressure

I ran another compression test today and got

1 2 3 4
DRY 68 76 76 71
WET 81 85 82 88


When I sent my head away to get skimmed and cleaned up, I measured the bore, extrusion of pistons from the block, the piston crown and the head volume (per cylinder) and gave them the figures. They reckoned I needed a 1.8mm head gasket to take it to standard compression.

I took that for granted as gospel and rebuilt my engine as such with a set of ARP studs and nuts as I am planning to run my t34.63 and greys on it.

Does anyone have any advice or suggestions? Should I just ditch the gasket and stick a group A head gasket on ? What thickness is a group A gasket and would the size be enough to give me my 60PSI back ?


Really appreciate your thoughts guys!!