bad valve seats?

[bcjjones]

What can cause multiple valve seats to go bad? The valves aren't bent nor burnt but about 8 valves aren't seating correctly.

Any help?

 

[slickers111]

Jumping timing..

 

[BogusSVO]

A badly warped head as the head bends into a U shape, the seats and guides can move .

The valves will grind straight, but will not seal on the seat

 

[bcjjones]

Timing was spot on....like I said the valves are not burnt nor bent

 

[jhicks92]

carbon build up maybe? or what bogus said, the head could be warped just a little.