hey all, just wondering if anyone knows if I can just shave my head 40thou without changing the bottom end.. wishing to up the compression a bit.. any replies are greatly appreciated! thanks, marc

I did mine but I put a h89 (a14) head on my a12 ,and I shaved it 60thou ,with no bottom end mods :)

Cheers

Yes you can.

Some people tend to mill them on a very slight angle as the majority of the combustion chamber volume is on the pushrod/cam side so by angle milling you are targeting the larger volume of the chamber thus making the procedure somewhat more effective in achieving 'more comp'. This angle milling procedure also ensures the valves are not situated as close to the crown as they would if it were milled level or square.

Whether you want to pursue that is up to you. I think most just deck them square.

Another way to get more compression ratio is to fit a thinner gasket. You can always put a thicker gasket back on but you can never (economically) replace the material you have machined off the head face.

The A12GX engine used a thinner head gasket.

Quote:

I think the original A10 head gaskets were also thinner? Can you confirm dd?

I also recommend the angle milling as Chris has stated.
It actually should improve ever so slightly the angle
of the inlet charge and swirl also.

I don't know about the A10 gasket thickness.

The best thing to do is use flat top pistons. Better than milling the head as it improves the quench performance.

thanks everyone, greatly appreciated! much performance difference with the shave?

Yes you can expect 2HP from the shave.