[Jimbobeast]

Originally Posted by P@blo

The seat pressure was not the problem in wiping your previous cam. If you used a high rate spring on a short IH, your spring pressure over the nose increased by a large factor. Unless your cam wiped the base circle?

Over the nose pressure on a HFT should be kept in check. Well, the ones you want to last anyhow...

I beg to differ. The aftermarket springs were installed without machining the valve stem "boss". The inner spring sat 1/4" above the seat (and the outer spring), giving an effective seat pressure of 160. The springs were OK for the application but were installed incorrectly (and assembled by a previously very competent Pontiac loving machine shop).
The boss is now machined and the inner springs are flat on the seat along with the outers. All is in harmony.