My speedshop called the valve supplier where they bought the valves from when we rebuild the engine. He says it's turning the lascaps and this causes them to eat-up the tips. Changing all intake and installing locking lashcaps.
@ Cab_Burge . It's a street engine. average rpm 4000 and max 6000.
@ Madscientist . There all checked for spring pressure and installed height.