Paul L

Following on from the thread on valve stem seals, I have tried to find the best available. It seems to boil down to fluoropolymer and fluoroelastomer materials. The former seems to be teflon. I am not familiar with the latter. What is the difference between these two materials?

kenincanada

Well Paul, I guess those materials arent used when manufactoring Angel Dust, PCP, Crack, ETC. :lol:

Noel Carboni

Well, I didn't get into molecular analysis, but last buildup I did this:

1. Machined the valve guide ends.
2. Installed teflon PC seals.
3. Installed umbrella seals.

Yep. Two different types of seals at the same time. The umbrella seals just fit over the teflon seals and inside the 3 piece springs. I believe they go up and down with the valves and keep the majority of the oil off the teflon seals.

I have iron heads and no valve guide inserts (i.e., the guides are holes through the iron).

Seems to work.

-Noel

68 Magnum

Quick answer - Teflon and fluoroelastomers are both fluoropolymers and I can't give you an answer as to which is best for your application.

Fluoropolymer and fluoroelastomer are interchangeable terms as far as we are concerned with valve seals. A fluoropolymer's physical properties could range from gas to brittle solid whereas flouroelastomer describes a flouropolymer with rubber-like physical properties. Viton is a well known flouroelastomer name suitable for use in seals of this type.

Teflon is a trade name for a flouropolymer. The word teflon has such a nice reputation with the general public that it is often used inappropriately to give the buyer a warm fuzzy feeling.

Scott

And yes, I am one of those supercool chess playing, El Camino driving chemists that supermodels are always hounding for dates. (Uh - do I need a smiley here?)

topless68

Paul L

Thanks. That explains the difference between Viton and Teflon.

Ingar, Norway

I installed Felpro seals a year ago and after 6k miles no problems, I had lots of blue smoke at startup before.
Inlet is made of a rubber like material (viton?) and the outlet of nylon, both are of the umbrella type. The original O-rings are also included in the set and should be used.