Umbrella valve stem seals in combination with o-rings y/n?

[Oliver S.]

I want to install the following umbrella valve stem seals

https://www.rockauto.com/en/moreinfo.php?pk=5571690&cc=1322941&jsn=501

As far as I understand they make o-rings obsolete. But some recommend using umbrella seals (I guess those with simpler design, i.e. without the spiral) together with o-rings on a valve. Any opinions on that?

Oliver

BTW: I know positive valve stems seals might be the best solution. However, I had to rule them out in my case.

[John F.]

Re: Umbrella valve stem seals in combination with o-rings y/n?

Interesting idea!

[Joe L.]

Re: Umbrella valve stem seals in combination with o-rings y/n?

I want to install the following umbrella valve stem seals

https://www.rockauto.com/en/moreinfo.php?pk=5571690&cc=1322941&jsn=501

As far as I understand they make o-rings obsolete. But some recommend using umbrella seals (I guess those with simpler design, i.e. without the spiral) together with o-rings on a valve. Any opinions on that?

Oliver

BTW: I know positive valve stems seals might be the best solution. However, I had to rule them out in my case.

Oliver------


I think these will work fine. I would use them in conjunction with the "o-ring" seals. This should not result in under-lubricated valve stems.

[Joe L.]

Re: Umbrella valve stem seals in combination with o-rings y/n?

I want to install the following umbrella valve stem seals

https://www.rockauto.com/en/moreinfo.php?pk=5571690&cc=1322941&jsn=501

As far as I understand they make o-rings obsolete. But some recommend using umbrella seals (I guess those with simpler design, i.e. without the spiral) together with o-rings on a valve. Any opinions on that?

Oliver

BTW: I know positive valve stems seals might be the best solution. However, I had to rule them out in my case.

Oliver------


One more thing I should have mentioned: Your valve springs should have an internal flat wire damper. You need to be sure that these umbrella seals will fit comfortably inside the damper and NOT contact the damper. If they do, they would be rapidly destroyed in service.

[Timothy B.]

Re: Umbrella valve stem seals in combination with o-rings y/n?

Joe,

Do those umbrella seals fit and stay put over the valve guide boss or just ride up/down on the valve stem and then above on the stem groove the o-rings are installed like factory.

[Joe L.]

Re: Umbrella valve stem seals in combination with o-rings y/n?

Joe,

Do those umbrella seals fit and stay put over the valve guide boss or just ride up/down on the valve stem and then above on the stem groove the o-rings are installed like factory.

Timothy------


Umbrella seals always move with the valve stem. They are not retained to the valve guide boss in any way. Positive seals are designed to be retained at the valve guide boss and the valve stem moves within them.

1955-1979 small blocks originally used only "o-ring" valve seals. 1965-74 Mark IV big blocks originally used only umbrella valve seals.

Whether used with umbrella or positive seals, the "o-ring" seals are installed as-original.

[Timothy B.]

Re: Umbrella valve stem seals in combination with o-rings y/n?

got it, thanks Joe. These unbrella type seals can be used on the hot exhaust valves as well?

[Joe L.]

Re: Umbrella valve stem seals in combination with o-rings y/n?

got it, thanks Joe. These unbrella type seals can be used on the hot exhaust valves as well?

Timothy-----


Usually, yes. For example, 1965-74 big blocks used the same umbrella seals on both intake and exhaust. The 1965-69 umbrella seals were different than the 70-74.

[Domenic T.]

Re: Umbrella valve stem seals in combination with o-rings y/n?

I would like to add that when doing a valve job, the valves and guides were usually worn from lack of oil. Then the Sunday driver that used stock ended up with build up on the intake valves and piston tops. GM had a solution in a can. Top engine cleaner. Car had to be out of the shop and engine warm and you poured the pint in enough to kill the engine @ about 2K. Others poured water down the carb to steam clean.
As a matter of interest, I had water injection on my 350 and when I took the heads off all was clean. Nothing on piston tops AND the water stopped the pining.

Dom

[Timothy B.]

Re: Umbrella valve stem seals in combination with o-rings y/n?

Domenic,

So you are saying that with just the stock O-rings and NO umbrella seals oil will lubricate well and even cause deposits on the intake valves.

Using the umbrella seals can do the opposite and cause lack of lubrication causing wear in the guides, correct?

[Domenic T.]

Re: Umbrella valve stem seals in combination with o-rings y/n?

Tim,
I guess what I am saying is that I prefer the stock system on the SB and the BB. I do have to run it hard to keep em clean. I do like the umbrella seals that move with the valve stem that let the stem and guide get a bit of oil. When I was on the line as a mechanic the seals that snap on the guide boss were popular. I noticed that they wiped all oil from the valve stem and I found more bad valve stems and guides on the ones that had them.
It's funny that aircraft valves and guides have nothing. No umbrella, O-rings, just a flat spring retainer and open spring.

Dom

[Joe L.]

Re: Umbrella valve stem seals in combination with o-rings y/n?

Domenic,

So you are saying that with just the stock O-rings and NO umbrella seals oil will lubricate well and even cause deposits on the intake valves.

Using the umbrella seals can do the opposite and cause lack of lubrication causing wear in the guides, correct?

Timothy------

Positive seals provide maximum valve stem oil seal. Umbrella type are next and stock 1955-79 "o-ring" least effective in oil control.


1980-91 Corvette small blocks used a positive seal on the intake and an umbrella seal on the exhaust. These were used in conjunction with "o-ring" seals and valve spring shields. The positive seals were an all rubber seal with retaining springs for valve guide boss and valve stem.

1992-93 and 94-96 LT1 and LT4 used positive seals on intake and exhaust. These were a metal frame seal with Viton insert with spring.

It is my belief that the majority of intake valve deposits are caused by oil which gets through the PCV system and oil drawn in from the lifter valley due to poor seal at the intake manifold-cylinder head interface.

[Oliver S.]

Re: Umbrella valve stem seals in combination with o-rings y/n?

I got the heads back from the machine shop. However, the assembling of the heads will be done by me. Initially, I intended to use a valve spring compressor clamp, but now I bought a valve keeper tool to remove and install them, which seems easy compared to the cumbersome clamp

https://www.lislecorp.com/specialty-tools/valve-keeper-remover-and-installer

It is explicitely mentioned only to use umbrella type seals (positive should be ok, too). So my initial question is implicitely answered now.

After having read a lot about valve stem seals types etc. I concluded for me:
Best seals in terms of preventing oil getting into the combustion chamber are positive ones - they work as squeegees . Since Chevy SB have their guides machined into the head, i.e. no extra SS or bronze guides, and, thus, require a certain lubrication (more than the extra guides as far as I know), positive seals may perhaps not be the best because they are “too good” for Chevy SB heads without extra valve guides. So O-rings or umbrella seals might be better to prevent valve guide wear, which comes at a cost, i.e. a bit more oil consumption.

Oliver

[Joe L.]

Re: Umbrella valve stem seals in combination with o-rings y/n?

I got the heads back from the machine shop. However, the assembling of the heads will be done by me. Initially, I intended to use a valve spring compressor clamp, but now I bought a valve keeper tool to remove and install them, which seems easy compared to the cumbersome clamp

https://www.lislecorp.com/specialty-tools/valve-keeper-remover-and-installer

It is explicitely mentioned only to use umbrella type seals (positive should be ok, too). So my initial question is implicitely answered now.

After having read a lot about valve stem seals types etc. I concluded for me:
Best seals in terms of preventing oil getting into the combustion chamber are positive ones - they work as squeegees . Since Chevy SB have their guides machined into the head, i.e. no extra SS or bronze guides, and, thus, require a certain lubrication (more than the extra guides as far as I know), positive seals may perhaps not be the best because they are “too good” for Chevy SB heads without extra valve guides. So O-rings or umbrella seals might be better to prevent valve guide wear, which comes at a cost, i.e. a bit more oil consumption.

Oliver

Oliver------


You're only going to be installing the valve locks ("keepers"). That's pretty easy to do. I really don't see why you'd need this tool. There MIGHT be some benefit using it for removal but I just don't see it for installation.

[Oliver S.]

Re: Umbrella valve stem seals in combination with o-rings y/n?

Joe,

since I haven’t done this before I watched some youtube videos, e.g.:

https://www.youtube.com/watch?v=qEe8C5u1LWg

Here the clamp and the Lisle tool are shown in action. The Lisle seemed much easier to handle ... place something in the cumbustion chamber as a resistance for the valve when tapping with the hammer.
I have also got the clamp and can practice on the old heads with old valves keepers and springs employing both tools, before doing it on the refurbished ones.

Regards
Oliver