1. khryslerkid

    khryslerkid FBBO Gold Member FBBO Gold Member

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    I'm doing a valve spring replacement on a set of 452 heads. I've already done the machine work for the positive stop seals.

    Reading info here and there, some are leaving the seals off of the exhaust valve. The fact being, the ps seals do such a good job and the valve doesn't get lubrication from the top, like the intake that's under vacuum. A practice thats done mainly for drag racing applications.

    So on a street driven engine, what's being used, ps seals and just use gas additives to make sure the exhaust valve is getting lubricated? Is there a ps seal for exhaust valves?
     
  2. dieseldazzle

    dieseldazzle Well-Known Member

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    I think that you can use umbrella seals on the exhaust
     
  3. coloradodave

    coloradodave FBBO Gold Member FBBO Gold Member

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    I've used Perfect Circle Teflon valve seals for many, many years on customer's motors as well as my own. I've never had a problem on street or race motors. I've read of problems, but that hasn't been my experience as long as the machine work is done correctly and the clearances are right.
     
    • Thanks! Thanks! x 1
    • khryslerkid

      khryslerkid FBBO Gold Member FBBO Gold Member

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      Thanks Dave. I have the Comp Cams 515 Vinton 3 seals. Should be comparable?
      I've replaced many back in the day, when there was good fuel to use. Now days I read all kinds of things and have to double check myself.
      Just finding the right spring combination, on a mild cam, shows just how much times have changed. Getting there!
       
      Last edited: Apr 29, 2016
    • coloradodave

      coloradodave FBBO Gold Member FBBO Gold Member

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      I'm sure you've seen this in the Comp Cam's catalog:
      Valve Stem Oil Seals COMP CamsĀ® offers a complete line of valve stem seals, a must to keep unwanted oil from entering the combustion chamber through the clearance in the valve guides . The o-ring seals use the standard retainer and oil splash shield . The umbrella seal is normally used when a larger-than-stock diameter spring is used, and in the case of a double spring, the positive-stop Teflon seal is used . Smaller diameter Viton seals are also available for triple spring applications . Both the o-ring and the umbrella seals require no machining, but with the Teflon seal it is necessary to disassemble the heads and machine the top of the guide with a special cutter, which can be found to the left side of this page.

      From what I can gather, the Viton and Teflon seals are similar, other than diameter. The 515s should be fine.
       
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      • khryslerkid

        khryslerkid FBBO Gold Member FBBO Gold Member

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        I bought a Sum6401 cam. At .488 lift, the retainer to valve guide is too close. So I bought the tool to take down the valve guide boss to the safe distance. Then of course you have to go with the positive stop seals. I did see one article on a bb Chevy build, where they used a different PS seal on the exaust. So that got me thinking.

        Thanks for your reply Dave!
         
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