The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 454 Valve Steam Seals: Umbrella or Positive?

**Desert1957** · 02-05-2012, 10:57 AM

Be aware some of the "positive" seals you have shown require machining at the the guide area for proper installation . only the "umbrella" style fit everything.

Desert

Here is a quote about the process I mentioned above form another site.

"Teflon or Viton positive stop seals are installed on a guide boss that has been machined to 0.530" diameter for a 0.001" interference fit and the seal bottoms on the valve spring locator boss. The stock Chevy spring locator boss is generally about 0.900" OD and must be machined smaller for dual valve springs. The Teflon and Viton positive stop seals has a spring that tightens on the valve stem and a spring that tightens on the valve guide boss and must be used with dual or triple valve springs. The one you have are Viiton rubber umbrella seals and they do not have a spring that tightens on the the valve stem.

Umbrella seals allow a small amount of oil to pass into the stock iron valve guide for valve stem lubrication. Virtually no oil gets past Teflon or Viton positive stop seals and that is why you should install K-Line Bronze Bullet (or equal) phosphor bronze valve guide liners to use those type positive stops seals. Bronze guides or guide liners have "self lubrication" characteristics."

02-05-2012, 10:57 AM	#9
Desert1957 Registered User Join Date: Apr 2009 Location: New Freedom Pa. Posts: 1,335	Re: 454 Valve Steam Seals: Umbrella or Positive? Be aware some of the "positive" seals you have shown require machining at the the guide area for proper installation . only the "umbrella" style fit everything. Desert Here is a quote about the process I mentioned above form another site. "Teflon or Viton positive stop seals are installed on a guide boss that has been machined to 0.530" diameter for a 0.001" interference fit and the seal bottoms on the valve spring locator boss. The stock Chevy spring locator boss is generally about 0.900" OD and must be machined smaller for dual valve springs. The Teflon and Viton positive stop seals has a spring that tightens on the valve stem and a spring that tightens on the valve guide boss and must be used with dual or triple valve springs. The one you have are Viiton rubber umbrella seals and they do not have a spring that tightens on the the valve stem. Umbrella seals allow a small amount of oil to pass into the stock iron valve guide for valve stem lubrication. Virtually no oil gets past Teflon or Viton positive stop seals and that is why you should install K-Line Bronze Bullet (or equal) phosphor bronze valve guide liners to use those type positive stops seals. Bronze guides or guide liners have "self lubrication" characteristics."