[MichiganMat]

see, I don't think of those as cracks as much as just burned material.

Bad compression? yes.
Leaking? yes
Catastrophic? im not convinced yet

Lots of cars burn their valves. Owners run them hot, electric fans stop working, thermostats wear out, scale builds up in the cooling system.

Maybe the wear and tear of near red-line RPMs will demand more strength from the valve head, I don't know. Is it common for valves to break off the stems?

we need to find an engine expert. John Walker maybe?