Spitting oil through tailpipes.

I was thinking more along the lines of a loose fit, as in too much clearance on the v. stem/guide, and a passive (umbrella ) type seal.

Big lift, aluminum head, 1 piece bronze guide, big spring psi... and how long was it run without a geometry kit?
The rockers just shove the stems, guides over, working them loose.
I've seen'em where you can grab a pair of Springs already on the head and squeeze them together and see them "stems/guides move, which is a lot if the naked eye can see it.