I lose at least two lobes on the cam, the first two times the cam moved forward in the block the last two times four difrent lobes have gone flate. this time it is the number 7 cylinder last time it was the number two cylinder.
You don't by chance have some incredibly strong valve springs fitted.
the machime shop worked the heads over and check my springs and replaced a few so I don't think I have a spring problem. I just thought I was an inept idiot who couldn't build a motor.(I almost feel better knowing it did the same thing after the machie shop built it)
I'd almost put money on a valve spring prob. Is there clearance so they are not coil binding? What cam are you using,solid /hydraulic? Do the lifters rotate freely in the block.? What oil are you using ? Cam endfloat???
Do you run the new cams in , @ 2000rpm for 20-30 mins,,,then put some kms, on it with out reving too hard. And always let engine get to operating temp, and oil temp is up to operating temp too...you will chew lobs off if you are thrashing it cold.