Lapping is also a good way to check for a slightly bent valve. It used to be the final operation of a machine shop valve job, but they got away from that with new valve grinding and seat fitting procedures that gave a better fit without using the abrasive compound. These days I use Prussian Blue instead of lapping compound to check valve seat position and width.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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