Anyone ever tried drilling tiny hole in PC seal for stainless valves with iron guides?

[bentvalves]

what is the story with hard teflon seals, why do the even exist?

I've seen them on early model Mercedes Benz and Ferrari cylinder heads, and thats about extent of my experience with them.

[engineguyBill]

what is the story with hard teflon seals, why do the even exist?

I've seen them on early model Mercedes Benz and Ferrari cylinder heads, and thats about extent of my experience with them.

Teflon valve seals work very well in severe environments such as high temperatures, extreme friction, fuel contamination, etc., etc. The major downside is the possibility that these seals take up too much room to be utilized with some performance valve springs. i.e. too large in diameter to fit inside multiple spring combinations.

[bentvalves]

metal clad Viton seals for the win?

sounds like Teflon seals are old-hat this day in age, but that is a question not a statement...

[ProPower engines]

There have been several different brand names up here and some better then others but I always have seen them
work too good and keep too much oil out of exhaust guides where it is really needed.

I switched to the metal clad viton seals about 20 years ago and never had an issue since.
They are easier to install then the teflon seals and are easier to remove in most cases. And if you need a bit
more oil on the exhaust just pull off the spring. They have a bit of a well to keep oil on the stem all the time
and they fit better on dual and triple spring set ups.