So I finally got my engine from Pennsylvania and I was rebuilding the heads and my question is when the umbrella seal is in place what keeps it down against the head and when putting the springs back on that little rubber O-ring slides down the valve stem is this normal or am I doing something wrong? Every one of the O-rings pushed down when I installed the valve springs, I tried to work the top spring retainer down around one of the O-rings without the spring to see if I was doing something wrong but it wouldn't go inside the retainer so I'm hoping it's right! Any help with this would be great and I really do appreciate it.

 

umbrella seals are free floating. They are meant to slide up and down valve stem. They are not like a PC seal that presses onto the guides. Also when using umbrella seals the rubber O ring seals are not needed.

When putting O ring seals on, you put spring and retainer on, compress spring, slip O ring on and put it in the groove, then put your locks on and release the spring compressor.

 

The umbrella type of seal rides up and down with the valve stem, and merely keeps oil from getting on top of the guide. They are better than O-rings but still not very effective.

The O-ring seal goes inside the retainer. As Night said, they are unneeded when using any other type of seal. Correct assembly is, put the shims and spring on top, with the valve fully closed; put the retainer on top of the spring; compress the retainer and spring; put the O-ring on the valve stem about 1/8" below the groove, such that it is just below where the bottom of the keepers will go; put the keepers in the groove; release the compressor. The O-ring seals the retainer to the valve stem, and can't slide down because of the retainer, and can't slide up because of the keepers. Its sole purpose is to keep oil that pools on top of the retainer, from running down the valve stem. Almost TOTALLY INEFFECTIVE. IMO, a complete waste of time and effort.

I don't use either of those types of seal if I can help it, as they are near worthless if the guides are worn. Worn guides allow intake vacuum to suck any oil that gets on the stem, down around the valve/guide clearance, and into the intake tract. I GREATLY prefer to use bronze guides (or inserts), which don't require lubrication; and "positive" seals, especially, Teflon ones. This combination gives the best oil control. Viton ones such as FelPro or PC require less precision in the head machine work but work OK if not quite as well. Using Teflon seals with cast-iron guides can lead to short guide and/or valve life from wear, as they need some oil for lubrication. This makes a bad combination for an engine that needs to run many thousands of miles (i.e. a street motor) but is fine for a race-only situation.

 

After sleeping on it last night I realized this and redid both heads this morning and all is good now. Thanks for the info on the different valve seals. I'm building the engine back stock basically just refreshing it with new bearings seals and gaskets other than that I do have to have the crank polished to clean and smooth the rods and mains but everything else is in good shape and with new seals, gaskets and bearings I believe the engine will be good for another 100k I hope!