i am in the process of rebuilding my engine, the head i have has had a few skims in its life, the cooper o ring is sitting flush with the alley on the head. will i still be able to use this head ?
(the valves arent sitting above.)

 

find out the thickness of the head and go from there, as that's just one of the many problems caused if it's too thin as there'd not be enough meat left by the valve seats to allow cooling and they'd more than likely just crumble away in no time at all.

 

They don't crumble they fall out, but if too near seats can be pinned in.
tabetha