Stock Hemi's are 5/16 and don't have lash caps from the factory. My friend ran them on a ford 11/32 valve, solids and kept loosing them, this was back in the late 80's and I thought the springs weren't stiff enough, but the cam manufacture said they were good, he finally got rid of them. There has to be a big gap for them to fall out. As for the mushrooming I have seen a chevy with a rocker ball wobble around and mushroom the valve but I haven't seen a mopar with hardened tips mushroom.
