454 Valve Steam Seals: Umbrella or Positive?

[savatreatabvr]

Anyone know what kind of valve steam seals are in a mid 70's 454, umbrella or positive type?

UMBRELLA


POSITIVE TYPE

[BigBlocksRule]

I run positive (viton) on intakes, umbrellas on exhaust since it needs a bit better lubrication.

[wyattglock]

Should be umbrella's.

Thats a pretty good idea on how you run your seals BigBlocks!

[BigBlocksRule]

Can't claim it as my own, I know a few builders that set 'em up that way and for that reason. Makes good sense to me, so that's the way I have 'em set up.

[savatreatabvr]

Got it, positives on (intakes) and umbrellas on (exhaust). Can they be reversed or can I use all umbrellas or all positives? Reason I'm asking is because my 454 isn't in a street rod it's in a old C20 work truck?

Originally Posted by BigBlocksRule

I run positive (viton) on intakes, umbrellas on exhaust since it needs a bit better lubrication.

[BigBlocksRule]

If you're going to go all one way, I'd go umbrellas, particularly on a work engine. You don't need to over clean the exhausts. I've even seen positives on intakes and nothing at all on exhausts in hard run apps like grain haulers, etc. that lugged when loaded. Plan to burn a little oil, but you won't freeze a valve in a guide!

[savatreatabvr]

Main reason I'm replacing them is because while adding oil one day it smoked pretty bad afterwards but quite after a few miles so I'm assuming the new oil was leaking down the valve stem so I'm guessing it's the valve seals. They are replaceable with the heads still on the block right?

Originally Posted by BigBlocksRule

If you're going to go all one way, I'd go umbrellas, particularly on a work engine. You don't need to over clean the exhausts. I've even seen positives on intakes and nothing at all on exhausts in hard run apps like grain haulers, etc. that lugged when loaded. Plan to burn a little oil, but you won't freeze a valve in a guide!

[Wrecked1982]

yes you can replace them on the block you need a air hose adapter that will screw into the sparkplug hole and turn the damper so the valves your working on will be closed

[Desert1957]

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."

[savatreatabvr]

As far as I know my 454 is stock, I don't drive it that much and when I do I'm not doing burnouts at stop lights so I think I'll go for the umbrella type, seems much simpler.

Originally Posted by Desert1957

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."