We checked with JMS' cylinder-head guru Pete Hillemeyer, who said the valves should look like they are sitting ON their seats rather than being flush with the combustion chamber as seen here on our Ford heads. That meant our seats were worn out and would need to be reground. Also, Hillemeyer showed us how to check the condition of the valve guides by wiggling the valve: The valve should slide in and out easily but not wobble back and forth during its travel. Our engine had previously undergone a cheapo rebuild that resulted in a few mismatched exhaust valves and bronze guides, which Hillemeyer doesn't like very much. He drilled out the bronze liners and replaced them with cast-iron ones.