Ok we covered the valve seats,but what about valve stem seals?

Do I stay with the stock O-ring seals?

Some have told me to use the stock O-rings and add Umbrella seals.

Some said to ditch the stock O-rings and just use the Umbrella seals

Then some have told me to step up to the Positive-stop seals.

While others told me the Positive-stops work too good and don't allow enough oil to oil the guides on a street motor.

Thanks vince

i used the positive stops. tom

Thanks Tom, I take it you've had no problems.
Did the ones you use require machining?

vince

The Viton seals are great seals.
I would just run those Viton seals.
Better than the o-ring or umbrella seals.

MBHD

Positive-stop seals work great except when you run oversize valve stems and a 500+ lift cam. Unless you trim about .250 off the valve stem towers you will peel the inside of them off when the step down on the stem goes inside the seal...Pulled my motor and took it apart just after a build looking for broke ring before I found tiny pieces of teflon in the pan....SCRAP

If you Install them with the Right tool AND what some guys call a (condom lol)Which is a sleeve for valve You will not rip the seals.The seals are installed after the valve is in the Head.Once the valve is sitting in the head you then put on the sleeve and Then Install the SEAL.Yes the valve guide boss does need to be cut for the seals.If for what ever reason you cut/rip the top of the seal You need to install a NEW ONE.
Once the seals have been installed and for what ever reason You have to put the valve Out,You
will end up cutting the top of the seal out and a NEW one is again needed.

Larry, THIS HAPPENS AFTER IT WAS ALL PUT TOGETHER !! When the valve opens the OVER SIZE stem (which gets larger about 3/4 inch below the valve keepers) goes inside the seal and when it comes out (when the valves closes) peels out the seal. I am running about .550 lift and had to shorten the towers .250 Then cut for seals to cure this problem...What I have learned from this is not to wimp out on putting in new guides by reaming worn guides and using .010 oversize valves that I had on hand out of a 350 v/8 rebuilt motor. Us old folks have to watch our pennys !! SCRAP

Larry thanks for the tip about how to install them,good stuff to know. Where do I find these condoms?

I notice that they have some that require machining and some that don't.

Scrap I can see where that would be a problem.

When you buy the seals they include 2 of the plastic "condoms". If your lucky and skillful you can install all 12 with it. The 11/32" are bought easier for a V8 and you have 4 left and 1 condom. Good luck

So do you have to do all this to install umbrella seals then? If you use umbrella seals do you still use o ring as well? A little confused! Thanks in advance. Have a fun day guys.
Slider

Jimmy thats a good idea buying a V8 set, just incase one gets tore I wont be shut down waiting for another one.

Slider,I was told you can use the Umbrella seal with or without using the O-ring seal, so not really sure which way is the right way to go.

G10-250 I guess my question really is do you have to turn down the valve guide boss to use the Umbrella seals. I don`t see why you would need too. But i don`t know for sure.
Thanks
Slider

Slider in Wa,,,,
No,, you do not need to machine down the guides to fit the umbrella seals.

MBHD

I just got done doing a head job (due to a broken timing belt) on a BMW 325i engine with 185,000 miles on it- it has the positive seal type seals from the factory. Even with that many miles on it and being over 15 years old the seals were still in good shape- the lips were a bit torn but the weren't leaking, but the guides weren't worn out of spec either. I'd put those seals on any head where you are in there already and care about the seals.

OK, need a little more info here...should the stock o-ring seals go above or below the umbrella seals? Seems like a silly question but I can see the merits of both sides of the umbrella seal/stock o-ring, above it takes the brunt of the oil before it gets to the umbrella, under it makes the o-ring an insurance against a breach of splash. What is the correct way??

Bump

Getting ready to do this seal replacement this weekend. ANY comments???

The O rings go at the top of the valve There is a groove for them.

Twisted6 I.I #3220 Thanks! question answered, will play tomorrow..

jb