[torqhead]

I noticed on two separate Pontiac v8 engine gasket kits that they only come with 8 valve stem seals, one of the packages in one kit had these clear plastic sleeves. (see pic)

Question is, do you only put the valve stem seals on the intake or should they have come with 16 in the kits? Also, what are the plastic sleeves for?

[lust4speed]

The seals included in the kit are rubber and intended for a pure stock rebuild of the head. Pontiac used the steel shields and O-rings for oil control. Today most of us prefer to toss the shields and O-rings and cut all the guides for the use of PC seals on both intake and exhaust, and Viton has become the seal of choice over the Teflon.

The clear plastic sleeves slip over the valve stem when you slip on the seals and are meant to protect the seal from the sharp groove edges at the top of the valve.

[Will]

The reason there are only 8 is because a stem seal on the exhaust side isn't as important as on the intake side. Positive pressure in the exhaust port helps prevent as much oil from going into the port as compared to vacuum on the intake side, and also if a little oil does get down the valve it's no big deal as it's not being sucked into the cylinder, it just gets blown out the exhaust.

[torqhead]

These are my original heads that only have a few hundred miles on them and the valve guide is stock as far as I know, see pics. Will the seals I posted work on the intakes?

[STEELCITYFIREBIRD]

Measure the diameter of where the seal seats, intake and exhaust. Order a set of Viton, metal body seals to fit....they look like they have been machined, but it's a pretty far away view in the pic. Their likely 0.530".

[steve25]

Those are not stock guide tops, they have been cut for positive seals.
As posted its hard to tell by a photo if they have been cut to work with .500" or .530" seals.
I would use Comp Cams 518-16 seals if your guide OD is .530", or 517-16 if they are .500" in OD.

With either of these seals ditch the factory O rings in the trash!

[Half-Inch Stud]

Originally Posted by Will

The reason there are only 8 is because a stem seal on the exhaust side isn't as important as on the intake side. Positive pressure in the exhaust port helps prevent as much oil from going into the port as compared to vacuum on the intake side, and also if a little oil does get down the valve it's no big deal as it's not being sucked into the cylinder, it just gets blown out the exhaust.

This upgrade alone "Modernized" the PMD V8 design to todays best practices....minus all the Bureacacy.

[GRX]

Agree about using Viton seals instead. They remain effective longer than those black ones.

Good chance ones linked below are what you need. Measure to be sure. And do use the included plastic sleeves in the manner Mick suggested in post #2.

http://www.jegs.com/i/COMP-Cams/249/518-16/10002/-1

[torqhead]

Originally Posted by steve25

Those are not stock guide tops, they have been cut for positive seals.
As posted its hard to tell by a photo if they have been cut to work with .500" or .530" seals.
I would use Comp Cams 518-16 seals if your guide OD is .530", or 517-16 if they are .500" in OD.

With either of these seals ditch the factory O rings in the trash!

O rings? Didn’t realize there was an O ring as well. I’m passing these heads onto a buddy of mine and our intent is to just swap them onto the 400 he has (currently has mismatched heads, a 5C and a 6X). So since these have low use and will bump the compression up a bit we were going to put new valve seals and just swap over the valve springs from the current heads and get it running again. Are we missing something?

[steve25]

Your buddy's motor may have very well been built that way from the factory with the two different head castings as that has been seen before in the middle of 1975 production as the 6 series heads where coming on line!

[steve25]

The second groove on the top of each factory valve is where the o-ring goes, the retainer and the keepers trap them in place.

[GRX]

Factory style O-ring in second groove works in conjunction with retainer and spring shield to act as a big umbrella. Positive locking seals fit tightly on the guide and do not move with the valve. Now the spring shield & o-ring can be omitted.

Be sure to check spring retainer distance from seal top at full lift. Should be 0.050" minimum.

Handy image:

[torqhead]

Thanks Steve25 and GRX, appreciate the info!

[torqhead]

Originally Posted by GRX

Agree about using Viton seals instead. They remain effective longer than those black ones.

Good chance ones linked below are what you need. Measure to be sure. And do use the included plastic sleeves in the manner Mick suggested in post #2.

http://www.jegs.com/i/COMP-Cams/249/518-16/10002/-1

Should these just press on. I measured them and they were .500 so bought the 517-16 but can’t seem to get them all the way seated.

[mgarblik]

Those are very nice seals but generally will not just push on. There are little drivers made to gently push them over the guide and "press" on. If you are very careful , they can be installed with a deep wall 12 point socket. Choose a socket that ID of the socket will just nest on the steel jacket on the OD of the seal, missing the blue Viton and garter spring as you don't want to damage them. Lightly oil the seal and guide and gently tap it on being careful not to deform the Viton.

[torqhead]

Originally Posted by mgarblik

Those are very nice seals but generally will not just push on. There are little drivers made to gently push them over the guide and "press" on. If you are very careful , they can be installed with a deep wall 12 point socket. Choose a socket that ID of the socket will just nest on the steel jacket on the OD of the seal, missing the blue Viton and garter spring as you don't want to damage them. Lightly oil the seal and guide and gently tap it on being careful not to deform the Viton.

Thanks, wanted to make sure I didn't damage them. The socket worked.

[steve25]

Oil up the guide before you go to push them on!

[track73]

I always worried the the PC type seals on the exhaust would keep the exhaust valves too dry. On a couple 4 cylinder midget race engines we built didn't even put seals on the exhaust. It would puff blue smoke when the driver got off the gas. My Buick nailhead had the seals on the retainer.

[mgarblik]

The old white all teflon seals gave some engine builders concern about valve stem wear and not enough oiling to the stems and guides. Pontiac engines put a ton of oil to the top of the engine, so I find lack of lubrication to be nearly impossible with any kind of seal. The blue ones installed by the OP are really nice. They work like a tiny windshield wiper blade. The viton and low tension garter spring wipe the oil off as the valve moves through the seal. But some will get by, just like a little water gets past the wiper blade. A few on here remove the garter spring from the exhaust seals to let more oil on the stem. I do not do this because I have to believe the engineers who designed the seals know more about valve seals and lubrication requirements than I do. I have had zero problems with the steel jacket/viton seals in over 10 years. I have installed hundreds of them.

[gtofreek]

^^^^^^What he said!^^^^^^ Exactly!