Hey guys, my friend recently got his entire motor professionally rebuilt, including heads.(85 2.8L) He had it bored and stroked out to 3.3. He's having some trouble with one of the cylinders and so today he took it apart to replace the intake seal on the number 2 cylinder because it was leaking oil. While he was there he noticed that there was no exhaust valve seal. After looking at the other cylinders he realised that none of them had exhaust valve seals.

So my question is is this just poor workmanship on the part of the guy who rebuilt it, or was it done on purpose? Has anyone ever heard of this? Maybe an old hot rodder trick?

Thanks for any help.

No quality control what soever should not have happened.

Every 2.8L valve guide seal kit that I've seen had a large seal for the intake and a very small O-ring for the exhaust. With out takeing it apart the O-ring can't be seen.

There are no stem seals on the exhaust valves, only the intakes. The reason is that the intakes are subject to high vacuum so they need extra sealing to keep oil from being sucked past the stems. The exhaust valve stems see only very low pressures so no seal is needed or installed. All the valves have a rubber seal under the keepers inside the retainer, it fits into the bottom groove of the stem.

JazzMan

Only the intake valves have the umbrella seals. Both exhaust and intake have small O-rings at the top of the valve stem under the spring retainer and keepers.

What purpose does that little o-ring serve? Does it keep oil out of the cylinder?

quote Originally posted by Elenor84: What purpose does that little o-ring serve? Does it keep oil out of the cylinder?

I believe it keeps the oil that puddles up in the spring retainer from running down the valve stem and between the stem and valve guide.

If this was absent, would it cause the cylinder not to fire?

That O-ring is there to keep the hot, thin oil from running down the valve stem and into the cylinder. This is the classic cause of that "puff of smoke" at the next startup. I doubt that the small quantity of oil that could puddle in the spring retainer could foul a plug.

A lot of old school engine builders would leave the seals out. this will help make the valve guides last a lot longer. I left the seals out when I built my 2.8(ARI stage3 cam, all arp bolts, ported heads, ported lower intake, gasket matched middle and upper int, ported ex manifolds). I have not had any problems from it. I have a slight wisp of smoke when it is started but I have had no problems with it running. The engine has about a thousand miles on it now including 4 autox's and to be honest I am hard on the car. The engine in my rollback(small block chevy) also does not any valve seals in it. That one was rebuilt about 4 years ago and has about 35k mi on it with no problems and no real oil consumption (less than a qt in 3k mi) it gets changed every 3k. If the guides are right it should not cause any problems to leave the seals out. I know a lot of people will disagree but this is from my experience.