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Improved L6 Valve Stem Seals


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As discussed in a previous post, I'm using Schneider's #68022 Spring set as sold by MSA on my new P90 head. This spring/retainer combination is advertised to support in excess of .600" lift before coil bind, with reasonable valve seat pressures.

 

However, this doesn't take into account the fact that the inner spring locating sleeve on the retainer is very long and will contact the stock type valve stem seal after about .475" compression. My new cam's lift is .515" on the intake side.

 

I instructed the machinist to check for this during spring height setup (Thanks for the pointer Jon) with instructions to shorten the retainers if necessary and he came up with a better fix: Shorter and better valve stem seals.

 

Turns out that there are some seals from a German Ford 2.9l V6 that fit the L head perfectly and are said to be made out of a better material (Viton I think). They have two of the little spring rings around the flexible seal, are made to work submerged in oil on an OHC head, and just look like a better part than the stockers. With these seals in place a valve travel of .600" plus can now be obtained with the unaltered Schneider retainers.

 

I'll get some more info and post pictures in the next couple days.

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*Sorry this isn't ment to be a hyjack, just additional info to Ricks post;

I ordered some oem seals from a old Datsun 4 banger that was refernced in the How To Build Your Nissan Motor book.

They are real stout, with steel case, and I belive that viton material. I think it comes off a "A" series Datsun motor. I'd have to dig up the receipt from Courtesey Nissan...

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I have not seen Nissan seals like that. I'm sure they are a big improvement over the stock Z stuff. Joel's look very much like the Ford seals - metal bottom part, low profile, but the Ford ones have 2 spring rings on them and green Viton seals. According to my machine shop guys, the Ford items are a very common item in stock in most machine shops. Pictures to come early next week.

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Yes, I used the "A" series Nissan units as shown above on several high-lift engine. They work very well, especially if you get aftermarket units.

 

The "A" series is the correct one---they fit like stock, are considerably shorter, and come from an OHV engine just like the Capri units.

I have heard of the Capri seals before, but have not used them myself. On another type of engine, we experienced valve sticking (retainer to stem grabbing) due to lack of lubrication from using a seal assembly off something else that "Fit" but sealed _much_ better than the stock OE seals. Sticking valves cause wierd symptoms...

 

But I have heard of Capri Seals being used, so you are probably O.K.

I used the "A" series units with good success.

 

Good Luck on the buildup.

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Guest bastaad525

Hey uh... same deal not trying to hijack or anything, but this is kinda on topic :)

 

Just wanted to verify, out of the stock Nissan L6 seals, which ones are the better ones, the brown ones or the black ones?

 

And, asides from the lower profile, would these other seals (the A series or the ford ones) offer any other benefit, such as longer life or anything?

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I've always heard brown is good, black is best, white sucks.

 

That's pure HEARSAY, so I really don't know, which is part of what ticked me off about the L6 valve stem seals.

 

If you change the seals make sure you get the plastic little straw-looking tool (slides over the end of the valve) which allows you to slide the seals right over the retainer area so they don't tear when you put them on.

 

It's hard to tell if either of the seals would function better, but its a fairly safe bet IMO, I've never had good luck with the stockers...

 

Jon

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I have not had good luck with stock type seals of any color, although the brown ones do seem to be the best.

 

The A series or Ford seals are a real improvement over the stock design as the rubbery sealing material is better stuff and the metal bottom sleeve that fits over the guide top has to be a more solid way of attachment. I believe they'll last longer and seal better, in addition to giving the height reduction I need.

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Just to let you guys know, we have just done an E31 head with a .508 lift cam at the shop, and we used these Ford 2.9 valve seals. With the .508 lift there were issues with the stock sized valve seals. I'll try to remember to update this thread once the engine gets driven some, but the first 20 minutes seem good. :)

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  • 5 months later...

I thought I'd add what I found with these seals. I bought some of the SS72686 seals for a large valve E31 head running a .570" lift cam with the schneider springs and retainers. In my case, the black felpro stock valve stem seals would have handled up to a .500" valve lift but no more.

 

The SS72686 seals fit very tightly on the guides. So tight they need to be pressed on. If the guides aren't nicely chamfered (on my head some were, some weren't) and lubricated, the seals will get torn and deformed during installation. Also, once they are on, they don't want to come off.

 

These seals will easily allow valve lifts of .600"+++

 

I picked up a second set of seals this morning. The first set I put on and took off _might_ still work, but for $20, I'm doing it right the second time. In hindsight, all of this should have been obvious. Oh well.

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  • 2 months later...

Just wanted to follow up on this....

 

Finally the new motor is running with no smoking issues ( Had it going but the dam Total Seal rings were sent with defective 2nd rings causing it to smoke like a biatch - rebuilt with new rings and everything's fine.) - It wasn't totally obvious where the oil was coming from. :evil:

 

I too can now recommend the Fel-Pro SS72686 seals for the L6 without reservations.

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