double valve springs and valve stem seal

[MoparCain]

Do the double valve springs for a big block take a special valve stem oil seal? Looks like there is not a lot of room for the umbrella type seal.

 

[Meep-Meep]

Yes, back in the old days we used the little white teflon seals and those required the top of the guide be machined to accept the seal.

 

[benno440]

440 source sell these teflon seals

 

[rev.ronnie]

I wouldn't use the old style Teflon seals. At first they restrict too much oil and the guides wear, then they "pound out" and allow oil to flow past. Those things are pretty outdated with all the new technology out there.

I use the blue Flourolastomer seal with the metal clad rubber base. They have a spring that controls tension on the stem.

Now I am assuming that you are using a stock head...
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You will need to machine the guide to .500/.535" to clear most dual springs with a .700" I.D. You will need to machine the spring seat anyway so the spring does not sit on the step below the guide boss. Using a lower spring seat or cup is the most desirable way to go.

If you use a spring without an inner damper, and a .800" I.D., you will still have to machine the guide to .625". Either way, no matter what you do, you want to machine the guide boss true to the guide bore for the seal to be centered perfectly. Just because a positive seal slips on, doesn't always mean its centered. Positive seals are pretty dependent on being centered to work correctly. They don't tolerate a lot of misalignment.

The Flourolastomer seals are pretty much the standard of the industry now. If you have any trouble finding what you need through any of the vendors here, let me know, I have hundreds of them.

 

[67 coronet]

just for interest as well,i figure you are changing to a big cam with those springs.check to make sure you have clearance for the lift you are gonna run on that guide before you get it machined.stock heads cant take a big lift cam without shortening the top of the guide.