I'm helping a friend change valve stem seals in his T/A. He has Sportsman II heads with the factory umbrella seals. His cams lift is .510/.517.

His engine has been eating oil so we set out to change the seals. We found that almost all of the umbrella seals are at the very top of the valve touching the retainer! WTF! How does something like this happen? The valve springs are 1.25" diameter...the only thing I can think of is the umbrella "shimmied" up the valve stem because of the compressing and uncompressing of the spring.

So how do you keep something like this from happening? We are going to replace them with positive seals but I have umbrellas on my new heads and would like to avoid this little adventure.

what gives? thanks

 

That's what they're supposed to do. They ride on the valve stem, and merely keep oil from dripping down the stem onto the top of the guide. Hence, "umbrella".

Positive seals stay stuck to the guide. Much better.

 

Fel-pro's intake seals are good seals when used on both the intake and the exhaust. Much better control than umbrella-style.
Although, there are people who believe that the exhaust valve should have SOME oil running down it, for cooling purposes.

 

Yeah but should they be touching the under side of the retainer? That seems like they are to far up on the valve stem.

 

No, not really.... pretty typical with a relatively high lift cam as he describes.... that's exactly what I would expect to see.

 

You're clost to the limit of lift for a typical Sportsman II heads assuming standard lenght valves, no machining on the guide bosses. You'll find that the umbrella usually ends up at the top anyway but you should measure how much space is left if there between the guide boss and the retainer at .510 valve lift. I wouldn't be surprised to find that the retainer is actually squeezing the unbrella seal's collar slightly against the guide boss at max lift. Then you'll definitely have seals up against the retainer.

 

Can I use positive seals on the sportsman IIs?
I measured the guide bosses and they were .575
this seems like an odd size.
I was hoping that the umbrella was getting dragged up the valve by the 1.25 spring so I went to the old summitracing and bought $500 worth of stuff including 1.44 springs.

oh yea its my car that V8astrocaptain was talking about just so you all are not confused.

what is this limit on the lift dependant on? Is that where the retainer would hit the guide boss? I suppose I need to figure that out quick because my 1.6 pro magnum rollers will be in in like 2 days.
Thanks for the help

 

If you plan on going with the Positive Stop Teflon or Viton style valve stem seals, you will have to have the valve guides machined down. The Sportsman's have unmachined valve guide tops that's why they come with the cheaper umbrella type seals.

 

Thanks for the info.

I guess I'll just stick with the umbrellas.