Teflon seals and valve stem wear

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jseng1

jseng1

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The buzz is that viton valve seals work better for street use whereas teflon seals seal too well and can dry up the stems resulting in accellerated wear. What have high milage Norton owners found?

viton seals (easy to install)
Teflon seals and valve stem wear


teflon seals (require installation tool)
Teflon seals and valve stem wear
 
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Nothing ?

The Teflon seals are very tight on the KW stems and that includes with the coil removed so will use the seals in the AN gasket set and hope they stay on the guide.
 
Time Warp said:
Nothing ?

The Teflon seals are very tight on the KW stems and that includes with the coil removed so will use the seals in the AN gasket set and hope they stay on the guide.
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Well , anything has to be better than the plastic type original type valve seals. Mine were running hard as a rock and riding up and down the valve stems causing hydraulicking effect of gathering up oil and pushing down into the guides. Smokey. Bought Kibblewhite seals and Black Diamond vales and fitted and all good to go. Guides weren't at all worn due to the excessive lubrication. I wonder how many owners rebore to oversize on realizing the smokings fun ,when they should pay more attention to head seals issues.
 
I ran teflon seals on my (street-driven) 1968 340S Barracuda and put over 100k miles on that engine. No issues with abnormal valve wear. Although I can't say for sure, based on what I've seen from observation, I suspect that there is more oil being deposited on the Norton valve stem than there was on the 340 valve stems. So I can't imagine there would be a problem with the Norton unless the valves themselves are of marginal quality.
 
I pulled a set of old teflon seals out of a US-sourced Combat head I was refurbishing a few years back. I don't know how many miles they had done, but I elected to refit them rather than the neoprene (?) OEM type I had lined up for the job. I rather liked them.
I've never seen them in the UK, but I don't get out much...
 
If using stock type seals you should at least get the ones with the springs on them. Better yet the Viton seals from Kibblewhite or summit racing. The teflon seals should be reserved for rare occasions when using a total seal gapless top ring (instead of a gapless 2nd ring) because a gapless top ring creates extra vacuum and can pull too much oil through the guide.
 
On one motor, I'm running the red Kibblewhite spring-less seals (style 1) on KW bronze guides and black diamond valves. Hope they stay on over time. They go on a bit too easy. Will inspect and probably switch for the spring seals the next time I have it apart.

Teflon seals and valve stem wear
 
Fullauto head on my 74 off and it had the red KBW seals, style 1. They are 8 years old and 10k on them. Still completely flexible. The stems on one of the KBW valve show almost no wear the other more but still serviceable. It never burned oil until the rings took a hit.
 
elefantrider said:
On one motor, I'm running the red Kibblewhite spring-less seals (style 1) on KW bronze guides and black diamond valves. Hope they stay on over time. They go on a bit too easy. Will inspect and probably switch for the spring seals the next time I have it apart.

Teflon seals and valve stem wear
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I run style 1 . No issues , but will try style 2 next time head is off as they did go on a little too easy by hand.
 
I had Style 6, considered using them once again then binned them.
It has the stock no spring OEM seals now, if it smokes I will simply pull the engine out and replace them with Viton.
 
Time Warp said:
I had Style 6, considered using them once again then binned them.
It has the stock no spring OEM seals now, if it smokes I will simply pull the engine out and replace them with Viton.
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But....which style Vinton would you use? Style 2 seems like it might be the way to go to me, but I don't have first hand experience with either. Cj
 
cjandme said:
But....which style Vinton would you use? Style 2 seems like it might be the way to go to me, but I don't have first hand experience with either. Cj
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I never knew there was that multiple choice.

They were so tight (# 6 ) you could hardly move them on the stems (even with the spring removed), it didn't even distort when I used it as a valve protector and still left a mark.

I think I will go Style 2 in the future.
 
In the automotive world, it is fairly well-known that the white teflon PC seal usually gets damaged when you pull out the valve and then the seal needs to be replaced.

Not a big deal because seals are cheap but it does add some time to remove and replace.

The red Viton seals are softer material so you can probably reuse them if you need to remove the valves.

I've had valves out twice last year!
 
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I tried Style 6 - impossible to it, the damn thing split trying to get it over the guide.
 
I would go for style #4 first and style #5 second depending on whats available and what fits.
 
jseng1 said:
The buzz is that viton valve seals work better for street use whereas teflon seals seal too well and can dry up the stems resulting in accellerated wear. What have high milage Norton owners found?

viton seals (easy to install)
Teflon seals and valve stem wear


teflon seals (require installation tool)
Teflon seals and valve stem wear
Click to expand...
Who is the source of this "buzz"??
 
I replaced a blown head gasket last winter. While in there, we replaced rings, light hone job, and put new valve seals on. The bike (74 commando, 10,000 miles) ran great but smoked all summer. At first we thought the smoke was just rings not bedding in. But after 1200 miles and no improvement, it must be something else. I just took it apart and found both seals off the guides. They were the standard neoprene ones. We made sure they were seated very well during install last winter.
Everything else looks ok at this point. Of course the "while you are in there" discussion brought up overbore, new pistons, rings, valves, guides, etc. But I am tempted to just pick a better seal (#2?) from the display in this thread, clean things up, put it back together and see what happens.
 
One issue is valve stem to guide clearance, What are you guys using for your clearance?
 
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