I installed a cometic .079 head gasket which was supposed to lower my compression to a safer 9:1, but after the install i didnt do a compression test so i dont know what it should read. even though my engine has 145k, before the head gasket it was between 205-215psi on all cylinders. now it reads 160, 165, 170, 175. I've only been boosting 6psi but i'm sure i f'ked something up. I dont think timing has to be retarded for 6psi so thats probably not the reason. would having the regular plugs do that much damage?

back to the question, what psi should the read after 9:1 gasket?

 

I have JE 9:1 pistons and got 175~180 across the board.

 

that sucks, so only one cylinder it doing its job

good excuse to rebuild, if only i had the money

 

No, if it was 50, 50, 50, 175, than only one cylinder would be doing it's job. Those aren't horribile numbers. With 145k miles I'm sure the rings are just getting worn out.