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Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: Frog ()
Date: March 10, 2017 08:04AM

On page 128 of Bob Helt's The Classic Corvair, 10th Edition, he states that the Teflon seal is not recommended because of potential oil-flow problems because of its tight fit, while the current "rubber" one will work fine.

I just received my heads from the machine shop; guess what valve stems were installed.

Are the Viton ones from Clark's the proper substitute for the Teflon ones? Can I get the "current rubber" ones at my local auto supply store?

Thank you.

Frog

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: Frog ()
Date: March 10, 2017 08:16AM

Follow-up to my topic. I decided to perform a search here--shoulda done that in the first place--but, the comments seemed inconclusive as to the better way to go; i.e., Teflon versus Viton. Davemotohead even suggested to not use any valve guides at all if the stems are "tight clearance."

Frog

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: vwbusman66 ()
Date: March 10, 2017 08:19AM

According to clark's catalog PG.6, valve stem seals should only be used on intake valves.

[www.corvair.com]

-------------
James Keller
Kingsville, MD (21087)
Currently Corvair-less but on the hunt

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: thewolfe ()
Date: March 10, 2017 08:23AM

Viton is the way to go these days. Some here might argue against viton because of their bad experience with poorly made leaky corvair viton main seals but I have found no issues using viton stem seals in my corvair. I just rebuilt my wrx motor and guess what the oem seals are? viton

Nate Wolfe
Portland OR
65 Corsa 180

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: gnvair ()
Date: March 10, 2017 08:56AM

Viton is my choice as well. Many oem seals are Viton. I have had cars with over 300k without ever replacing the seals. They are also a lot more tolerant if the valve stem is less than perfect. Teflon on the other hand are very intolerant of a less than perfect stem.

Lee J
Southern New Jersey near Philly.
1966 Corsa 180/4 speed
1969 Monza convertible 140/4 speed

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: v8vair ()
Date: March 10, 2017 09:13AM

So has anyone ever seen a failure due to running seals on both intake and exhaust ?

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: Frank DuVal ()
Date: March 10, 2017 09:50AM

Yes, the exhaust valve stem suffers lack of lubrication if seals are used on them.

Intakes only!

Frank DuVal

Fredericksburg, VA

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: v8vair ()
Date: March 10, 2017 04:15PM

Did the Valve stick in the Guide,Gaul? what failed? Mike

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: MattNall ()
Date: March 10, 2017 04:31PM

Got to remember our Valves are Horizontal..... not vertical or canted.... oil runs down hill!

Same reason our lifters clatter easily..





MODERATOR
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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: v8vair ()
Date: March 11, 2017 05:55AM

I thought this was pretty informative, Off the Felpro website.
VALVE STEM SEALS

Valve stem seals are small relative to other gaskets and seals in an engine, but play an important role in lubrication. What makes valve stem seals different than almost every other type of seal? The answer is simple – they are designed to leak. Seals designed to leak may sound counter-intuitive, but the amount and way in which they leak is precisely controlled to achieve a specific goal.

vss1Valve stem seals provide a controlled leak of oil to allow the valve stem to be lubricated as it slides in the valve guide. The amount of oil that passes by the valve stem seal must be precisely controlled, as too little oil causes stem and guide wear. Too much oil causes carbon buildup leading to valve seat damage, decrease in volumetric efficiency, increased emissions and excessive oil consumption.

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: dragvairclark ()
Date: March 11, 2017 08:56AM

Your best bet is to not use valve stem seals. As long as your guides are in reasonable shape you don't need them. Matt Nall has the right answer. Corvair valves go uphill so oil does not run "down" the Corvair valve stem/guide.

Clark Hartzel, Fraser, MI
1965 Monza coupe

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: v8vair ()
Date: March 11, 2017 09:17AM

You may not need them but as little as it might be, i think it cost HP. Im not restricting the oil to the valve covers,so in the turns im hoping to fill the covers with oil to help cool the heads, Springs,guides, etc. Esslinger keeps the valve cover filled with oil on there midget engines to help cooling. We all know the mess that adjusting the valves running can make so i dont think the valve guide angle plays into it. Oil is everywhere and with the scavanging effect of the exhaust or large overlap cams which can pull oil through the exhaust guides during the intake stroke you might find an HP or two. When you only have maybe 200 hp a little here and there can make a difference. Just My opinion. Mike

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: gnvair ()
Date: March 11, 2017 09:31AM

The only down side can see running seals on the exhaust is that you will have to replace the guides (and maybe valves if the stems wear)as regular maintenance. If you are ok with that in exchange for what might only be a few horsepower then so be it.
If it is something street driven or something you want some durability out of then I would not run them.
I run them on the intake on all my cars including my Buick. No issues..........but I also run camshafts that have minimal or NO overlap.
I know there are Corvair guys that do not run them on the intake side (Chris Langley) and feel that if the stem to guide clearance is good then there is no issue.
My opinion is street car definitely on intake. Race car is optional.

Lee J
Southern New Jersey near Philly.
1966 Corsa 180/4 speed
1969 Monza convertible 140/4 speed

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: Frank DuVal ()
Date: March 11, 2017 11:28AM

Mike:

Worn valve guides and stems. That's what I have seen on heads with exhaust stem seals.

Frank DuVal

Fredericksburg, VA

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: vairchet ()
Date: March 11, 2017 12:18PM

Valve stem seals aren't necessary if you have guides and valves within tolerance. Oil usage is minimal. If installing valve stem seals, it is suggested only on intakes, not exhaust.

Chet in Ramona

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: Frog ()
Date: March 18, 2017 08:40AM

As I stated at the beginning of this thread, my just-arrived heads had the nylon seals installed. I also just received from Clark's a set of Viton valve-stem seals.

All the comments notwithstanding, if my engine man says he'll remove the nylon seals and install the Viton ones for free, should I go ahead and do that? Is that a "duh!" question?

Thank you for all the comments.

Frog

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: chris ()
Date: March 18, 2017 10:01AM

I'd say if you have the Viton seals and he'll replace them for free, go for it! I guess it costs some time but if it's a better set up it's worth it.

'65 Monza 4 door
4 speed
110hp
Gardner, KS

Heart of America Corvair Owners Association

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: vairmech ()
Date: March 18, 2017 11:04AM

I have posted about this many times on here.

With new guides you do not need any stem seals on a Corvair! BUT, how long do they stay in tolerance! As they wear the intakes will start sucking oil through them. When will this happen? Probably after about 10,000 miles. Race cars generally don't get that kind of mileage on them so you could actually not run a seal on the intake.

Also, I will NOT run any of the teflon stem seals any more, Viton only! Why? Ask your machinist to remove the spring for you and then try to push the valve out. You will probably have to push quite hard to move the valve with the Teflon seal. For those of us that run higher RPM's how much does this contribute to valve float? Then have your machinist install the Viton seal and then push on the valve, you barely have to touch the valve to move it. The Viton are easier to install and don't tear like the Teflon will.

Does the Teflon work? Yes. But the Viton seals work just as good. I have even Re-Used the Viton seals! Can you do that with the Teflon? I bet not, I have never been able to get one off in one piece.

The intake valves actualy will get a vacuum on the stem and suck the oil right past the guide. When new this is not enough to cause an issue. Why not run seals on the exhaust? The exhaust has some pretty harsh conditions to operate in and on most street cars actually have a positive pressure at the stem so any lube that gets in there you want there.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: 63turbo ()
Date: March 18, 2017 07:29PM

It takes a lot longer than 10000 miles! My heads have 50000 miles on them, and
the guides are still well within tolerance, and have never had valve stem seals, and aren't blowing oil.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: Teflon versus Stock "Rubber" Valve-Stem Seal
Posted by: jjohnsonjo ()
Date: March 19, 2017 05:47AM

My personal recent experience. I used the Teflon seals even though I thought they would really limit the oil flow to the guides since they were so snug. I also used roller tipped rockers. The advice here at the time was that you didn't need to hog them out for anything but a 140. I got some valve noise during my run in that turned out to be the rockers rubbing the studs. When I took the valve covers off I also found little blue pieces of rubber and couldn't figure out what is was. It turned out to be pieces of the seals. The machine shop had put longer than normal guides in the heads. This caused a slight collision between the keeper and the seal. I had pre-lubed all the guides during the build. Anyway the ones with the damaged seals worked smooth as glass. The ones with the seals intact felt scratchy, as in lack of lube. I added oil to those and they smoothed right up. So now I am running with no seals. I have about 5K on the engine and at some time in the future I will inspect them for wear.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

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