[cycleguy55]

Originally Posted by Moriarty

I'm replacing the valve seals on my 427 w/ aluminum heads which appears to have bronze valve guides that are threaded like these:
Manley Valve Guides | Northern Auto Parts

The seals I am replacing are these teflon ones to fit double springs:
COMP Cams: (16) Positive Stop PTFE Valve Seals: For 3/8" Valves & .530" Guides

They have little metal bands around them to stay tight under temp.

I was hoping I could just get them off by unscrewing them, but haven't had much luck there. I'm not reusing them so it's okay if they get damaged prying them off or whatnot.

I'm more concerned about making sure I install the new ones without damaging them so I don't have to wait around for a new set to arrive.

Given my inability to screw the old ones off (at least by hand), I suspect I will have difficulty trying to screw the new ones on. Are these meant to just be pressed on like normal valve seals? My understanding is that the threading is to provide extra grip so they don't slip off. Simply pressing them on seems like it might damage the nylon in the process and make that less effective. Maybe the metal band is meant to be pried open like a snap ring? That also seems like a good way to damage them though.

Finally, I'm wondering if I should apply a bit of oil or assembly lube to aid the process, or if that would defeat the point of the threading in the first place.

Thoughts?

The threaded guides say they're 0.502" O.D., while the teflon seals say they're for 0.530" O.D. guides. Am I missing something?