Last question of the day...
TFS recommends using neoprene rubber valve guide seals because the valve stems need more
oil than typical heads. Not sure I agree with this, or all canted valve engines would be using them.
Neoprene seals work for a few thousand miles, get hot and harden, suck
oil, and after 10k - 15k miles, there's an inch of hardened crud on the underside of the intake valve.
I've always used PC
oil seals with the teflon insert, and they last forever.
Felt like an idiot telling the machinist to to remove the teflon seals he'd installed, and put the rubber ones back in.
Comments? Thoughts? Experience?
Even considered polymer coating on the valve stems or guides. Oil retentive on the stem, oil rejecting on the underside. Anybody ever try this? I did put an oil retentive coating on the valvesprings for cooling when I installed them.