Z1OwnersClub GB

Hi, new to this forum, I am restoring a z9 A4, think the head might be warped, what is the max that can be skimmed off it.

Thanks in advance

hi don, welcome aboard, it would be very unusual to have a warped head. I'd have it checked by a specialist engineer or possibly a fellow member in your area. anymore information of the symptoms? obviously a hard one to accurately diagnose,but there are plenty of experienced guys here willing to help. cheers mark

Beware !
Before doing anything you need to check that the cams rotate freely in their shells with the head off.
Do each one separately whilst bolted down with their caps and the valves out.
If they spin free then you are safe to skim the head.
The head can be skimmed right up to the valve seats but this obviously raises the compression substantially so you would obviously take off the bare minimum to achieve a flat surface.
0.5mm off equals an approx 2cc reduction in combustion chamber volume and a 1 point increase in comp, so 9 to 1 would become around 10 to 1.

zed1015 wrote:Beware !
Before doing anything you need to check that the cams rotate freely in their shells with the head off.
Do each one separately whilst bolted down with their caps and the valves out.
If they spin free then you are safe to skim the head.
The head can be skimmed right up to the valve seats but this obviously raises the compression substantially so you would obviously take off the bare minimum to achieve a flat surface.
0.5mm off equals an approx 2cc reduction in combustion chamber volume and a 1 point increase in comp, so 9 to 1 would become around 10 to 1.

+1 rob, you're the man i hoped would add a reply. cheers m

Cheers, thank you