Hi

Car came in with misfire on removing head number 4 valve seat had come out, had seat and 4 valves replaced new hydraulics, refitted head but now on same cylinder misfire below 12000 rpm.

Running compression shows it low on this cylinder,cylinder leak back test shows everything sealing OK. I know cam lobs are sweated on and i think i am wondering if one as moved slightly causing this and possible cause of valve seat going, but don't know how i am going to prove it as possibly only a few thousands out

Any body have issues before?

Michael