In that case, it sounds like your machine shop has done a poor job of fitting the valves to the guides. It's not possible to use modern engine tight clearances on the older ones- - - -the valves get hot and sticky if they don't have enough clearance.
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
Love your enemies and drive 'em nuts!