Do you have viton seals on the exhaust side too? I always ran basic umbrella's on the exhaust side. Those guides get a lot hotter then the intakes so they actually like a little oil, plus there's no vacuum there.
I have done this in the past too....it was explained to me that the guides lived longer by getting a little more oil.
This was on a series of big Fords and I never had any trouble taking the guides out.......but I don't know if using a P.C. type seal on the exhaust would have made a difference there or not.
I was told that it was more critical with a heavier valve.
It worked on paper. :D
