Valve Stem Seals for stock HP 906 heads.

[birdsandbees]

Anyone have a source for the proper valve stem seals for double spring HP stock 906 heads?

Every set I find says "not recommended for double spring valves"! 

[b5blue]

Mopar P3690963 3/8" inside, P4876099 11/32" inside, P4876100 5/16" inside 

[birdsandbees]

Guess I'd better measure the valves and then hunt the right ones down. Thought all the stock HP heads had 3/8" valves...

Edit to add... Mine has the long "rubber" umbrella style seals currently in it and nothing like the 963 part number. Guess I'd better pull one apart and measure the guide boss diameter before ordering anything.

[John_Kunkel]

The MP numbers listed above require the valve guides to be machined. I think you'll find that dual springs will require guide machining, I don't know of an umbrella seal that will fit with dual springs.

https://www.youtube.com/watch?v=7aTXiay8M9k

[firefighter3931]

The MP numbers listed above require the valve guides to be machined. I think you'll find that dual springs will require guide machining, I don't know of an umbrella seal that will fit with dual springs.

https://www.youtube.com/watch?v=7aTXiay8M9k

John is correct ; double springs will not work with a stock umbrella valve seal. 

Are your springs really a double or are they a single spring with a dampner ? 


Ron

[birdsandbees]

They are stock HP 906 heads with the double spring (inner one being the light damper spring as originally mfg'd) on 383 and 440 Magnums. I checked my spare set of heads in my parts crate today and they are an umbrella seal as well.

[John_Kunkel]

A single spring with a flat steel damper isn't a "double spring" and most any umbrella seal will work with them. Seals made from silicone seem to last better than the other rubber types.

[birdsandbees]

Thanks John!

[firefighter3931]

A single spring with a flat steel damper isn't a "double spring" and most any umbrella seal will work with them. Seals made from silicone seem to last better than the other rubber types.

Exactly....a single spring with a dampner will work fine with an umbrella seal. That's why I asked for clarification. 

Comp makes a nice spring that works fine with a flat tappet cam and the oem retainers & valve seals. Part #911 if you're thinking about installing something fresh. It wouldn't hurt to have the current springs checked for seat/open pressure. 


Ron

[birdsandbees]

Thanks Ron!

[Dino]

I just installed the 911 springs on mine, on Ron's recommendation, and I ordered the MP seals but Mancini sent me their own brand. It had the exact same part number so it probably is the exact same part but here's yet another vendor who sends me parts I didn't ask for. Not shopping there again!

Anyway, the 911 springs are great and I paid less than $90 shipped for them.   

[birdsandbees]

Thanks, and I've voiced my thoughts on never buying from Mancini again a few weeks back. The original thing that started my order was no longer available, yet they never bothered to mention it.

[Dino]

Same here. My invoice was quite a bit higher than planned because several parts on their website were no longer available so they replaced them with more expensive parts. The Mancini seals they sent because they would have to order the MP seals first...well then order them!

Never got the courtesy of a call or email so lesson learned. I'll shop elsewhere from now on.

[birdsandbees]

Well based on research and advice I had ordered the P4120492 seal kit for 3/8 valves and when they came in I tossed the package on the massive assembly parts shelf.

Now today expecting to change out all my seals they are not the same as what I have. Mine go over the valve stem but clear the boss and for all intensive purposes would "travel" with the valve stem. The P4120492 kit came with 8 seals that go tightly over the boss and 8 that are just an "umbrella".

Can I use these.. or should I continue to source what I'm removing for an exact replacement. I actually have another set of heads with the exact same seals... and they're still soft.... so if I'm stumped I guess I'm stripping seals from the spares.

[PRH]

Just put 'em on..... That's how they come now.

Posi's on the intake, short umbrella on the exhaust.

[birdsandbees]

THANKS!! ... "locked up" on the intake valve and floater on the exhaust so it gets a bit more oil!! THANKS!