I am having a machine shop do some well maching on my engine. I was going to have them install the o ring valve seals along w/ umbrella seals; they said that they recommend that they machine the heads for $100 to install spring loaded ones (or something to that effect). I was also told to upgrade my springs even though THIS engine devloped all it's power below 4k where as the springs wont kick in untill 4k+.

What do you guys think, umbrella seals and stock springs or spring loaded seals (or something like that) and high performance springs???

Thanks guys,
-SuperchargedRS

 

Positive seals are probably what they meant by spring loaded. There's a little retaining ring that closes around the seal that holds it in place. Both umbrella seals and O-rings are mediocre, at best, when it comes to oil control.

Fel-Pro makes positive seals, made of viton, that slip over the factory guide boss. All others require machining to fit.

 

The Teflon seals are the way to go. IMO they're worth the cost to install them. They are the only thing I will bother with on my own heads.

 

Thanks for the replys guys, So between the teflon ones and the positive ones which are better, which last longer?


Thanks,
-SuperchargedRS

 

The Teflon ones are "positive". The other "positive" type is like the Fel Pro ones, which are various kinds of rubber materials, which deteriorate with heat and age. They look and work just like the ones in the pic, except they're thicker and larger to fit over some stock guides.

The Teflon ones basically never wear out. They are the way to go if possible. The others are a substitute.

 

I will go with the teflon ones, seems to be the way to go.

THANKS,
-SuperchargedRS

 

Your other option is factory PTFE (Teflon) seals that fit many later heads without machining. The factory seals are position sensitive, in that there is one type intended for exhaust valves and another type for the intakes (mostly related to seal lip contact pressure). You can have the machinist check your upper valve guides to see if they are machined to fit seals or just rough cast for the old type seals. If they are factory machined, you can use the LT4 stem seals. If not, you probably should pay for the machining to fit aftermarket Teflon seals.