What the Bulley is talking about is called "staking" a valve in aircraft
terminology.  You place one end of a plastic or wooden rod up against the
valve stem and them give the rod a few whacks with a hammer.  This is supposed
to knock any carbon deposits on the sealing side of the valve loose and give
you better compression.  Worth a shot I guess before pulling the head, however
since you are going to have to remove the cam to get to the valves I don't
know how much actual time you are going to save doing this versus just
removing the whole head and inspecting it.
Have fun.
Ken Wilford
Van-Again
John 3:16