He is a mechanic and he always uses lunati stuff just one of his routines, Ive never personally changed keepers but he said he dropped a valve in another motor years ago at the keeper and since has always changed the keepers every racing season, their cheap so why not I guess?
Anyway the valve broke at the bottom where it tapers down near the seat not at the top where the keeper is, I was thinking fatique was a factor since it broke at that point.