Valve Stem Seals

[type26owner]

Pioneer brand #OS-1072 (USA), 10.5mm guide, 5/16" stem, .38" length, positive type , spring-loaded teflon Available at Pepboys, Autozone, Kragens.....almost everywhere in the states.
<a href='http://www.pioneerautoinc.com/index.htm' target='_blank'>http://www.pioneerautoinc.com/index.htm</a>
-Modify steel spring washers as shown on the left-hand side with a 9/16" (.56) hole to clear the seal's .54" OD.
-The valve retainer keepers must be shortened by .06". Grind away the material being careful to not overheat the hardened keepers thus annealing them.
-Cut OD of guide to 10.5mm and shorten by about .06" so the seal butts against the shoulder or wire ring on the guide which stops the guide from slipping too far into the head. Radius the edge a little to allow the seal to be pushed on without chafing it. These cutting tools can be purchased. Used a battery powered hand drill to do the work.
-Trim the plastic installation tool sleeve in length so the closed end butts up against the end of the valve stem amd long enough so it cover the keeper grooves.
-Use synthetic oil. The amount of oil making it past this seal is only a few monolayers thick I'm guessing. That's plenty with a tough-chained hydrocarbon oil like the synthetic. Not sure dinosaur oil will be okay.

This only works for a cam with .35-36" of lift. The small end of the seal actually enters into the tapered pocket through hole for the keepers in the spring retainer. That's why the keepers need to be shortened. IIRC, if the valve does not float there is .05" clearance between the seal and the keepers. It's close but works great. The seals need replacing about every 50k miles. This particular size of seal was chosen because it's OD clears the ID of inner valve spring so there is no contact. Most importantly it's rather short at only .38" in height where as almost all the other cloices of seals are at least 1/2". Heard the argument that shortening by any amount the bronze guide is a mistake. Actually what the seal does is add a rather stiff linear bearing structure with an interference fit onto the the end of the guide. If anything it makes the valve stem stay centered in the guide with higher precision and possibly provides lateral dampening. After 50K miles my guides measured zero wear. This link below takes you to the folder 'Twincam Valve Stem Seal'
<a href='http://briefcase.yahoo.com/[email protected]' target='_blank'>http://briefcase.yahoo.com/[email protected]</a>
-Keith

[type26owner]

Martin,
Here you go! The engines didn't have any seals and that's why they all burn oil. It's the exhaust guides that do most of the oil leaking since there is not any drain holes on that side of the head. As a result the oil puddles around the exposed stems.

[lotusanglia1965]

Keith, many thanks for swift reply,and in such detail. I'll seriously consider this for my road car on standard cams,also they may be a good source for e-type i'm working on at work.People forget how bad oil consumption was on older engines. Many thanks,
Martin

[fjbm]

Hi All

I've found this very important thread but I cannot find any information in Europe for this teflon valve seals.

Images or any other info which was shown in the URL that was mentioned is not there any more which makes it ever more difficult to determine the car that this stem seals were for in the first place and the modifications needed.

Can anyone help me here?

I would like to fit these in my engine!

Thanks

[paddy]

Keith Franck doesn't post here any more but you should subscribe to a forum of his:

http://autos.groups.yahoo.com/group/vin ... ogygarage/

and ask the question there.

I think he mentioned making some of these stem seals recently.

Paddy

[Galwaylotus]

I recall a discussion on this some time ago. One school of thought is that seals prevent the necessary lubrication of the valve stems. Don't know whether that's a valid concern but just figured I'd toss it into the mix!

[alexblack13]

Hello men!

I don't mind the car using a little oil. Its the blue smoke on start up after the car has been sitting for some time that I dislike..A lot! As we know this is because oil drains down the exhaust valve guides (mainly!) and gets burned off on starting the engine.

Two solutions possibly.. The best would be a good oil seal. the other option is to get the oil draining out of the valve stem area better. Has anyone ever used an exterior drain pipe system on the exhaust side? Or any other method of draining the exhaust side better?

Alex....

[reb53]

I know it doesn't help but I'm reminded of the immortal words of Colin Chapman when he was asked by a journalist why the road-test Lotus was using so much oil.

"Of course it uses oil.....what do you think is lubricating it?"
(As though it was the most stupid comment he'd heard all day.)

You can see why he went so far!

Ralph.

[alexblack13]

Says it all eh?

Would not work today though!!

Alex....

[fjbm]

Hello men!

I don't mind the car using a little oil. Its the blue smoke on start up after the car has been sitting for some time that I dislike..A lot! As we know this is because oil drains down the exhaust valve guides (mainly!) and gets burned off on starting the engine.

Two solutions possibly.. The best would be a good oil seal. the other option is to get the oil draining out of the valve stem area better. Has anyone ever used an exterior drain pipe system on the exhaust side? Or any other method of draining the exhaust side better?

Alex....

Hi

Did anyone ever tried this?

Thanks

[john.p.clegg]

I tried,and it seems to work,after the guides have been fitted,using a home-made tool shaping the top of the guide to a point,rather like a pencil sharpener,difficult to explain but it tends to "scrape" the oil away from the stem whilst running and doesn't allow oil to sit on the top of the guide when stationary,wnile still letting the guide keep its length...

John

[nmauduit]

to keep alive a thread started some years ago, I'm overhauling a "Vengantune" engine (701M) I've had for 30 years or so, probably a mild but carefull preparation of the era, and the head has valve stem seals.

Discussions were held with the machinist and we concluded that we'll do without, his point being that extra lubrication even at the cost of oil is favorable to the engine, and mine being not to have a headache to fit them with Q420 higher lift camshafts...

[Chrispy]

I've currently got my head off at the machine shop getting modified to take seals as per this:

http://www.lotus-europa.com/manuals/lot ... EN079.html

The smoke was getting embarrassing to the point someone was going to dob me into the EPA and it needed guides anyway, so might as well do it properly!