The Stovebolt Site Forums The Shop Area Engine Shop Valve seals

on my 216 head I am ready to install valve seals then the valves. The seals I see a o-ring style. Are these still the preferred seal or is there another that is better. When installing the o-ring seals inside of the valve guide, Do I use one at the top and one at the bottom or just use one seal?

Thanks,

Coltonk

1950 Chevy 3100 -216 engine

Should be a groove in the valve below the one the keeper go in. Compress valve spring, install seal into bottom groove, install keepers in top groove, release compressor.

"Inside the valve guide"????? I don't think I've ever seen a guide with a groove for a seal like that. There is an aftermarket "umbrella" style seal that slips onto the valve stem before the spring and retainer is installed, but if you use that type of seal, DO NOT also use the O ring under the split keepers. It's possible to do too good a job of sealing oil and wear the guides out from lack of lubrication. Use either the umbrella seals (not included in a head gasket set) or the O rings, but not both at the same time!
Jerry

There is another alternative. Instead of removing the cast iron guide and replacing with new (I cracked a head once removing an old one so I don't remove them any longer), you can have your machinist install a bronze liner in the old guide, then cut the top part of the guide for a Teflon seal, often times referred to as a PC seal (Perfect Circle but lots of companies now make them). I do not use them with just plain cast iron guides, but always with the bronze liners. Between the little bit of lubricant and the bronze which itself is a lubricant, the combination works pretty well. Used on plain cast iron, might be too little lubricant getting to the guide and stem leading to a seizure of the valve stem to the guide. Your machinist has to know what he is doing with these Teflon seals because the valve stem and guide does need a little bit of lubricant so sometimes a valve stem has to be polished just a bit to get the right clearance. Its not hard but the Teflon seals are much more durable then the rubber seals.

The trick to removing cast iron guides without damaging the head is to drill the guide out until it's only got a wall thickness of 1/16" or a bit more. That relieves most of the press fit and the guide moves a lot easier. Most machine shops stopped using bronze liners sometime ago- - - -too much labor time involved in reaming the guide, fitting the liner, and reaming again for valve stem clearance. Maybe on a race engine - - - -not for general street use!
Jerry

watching the Hagerty stovebolt rebuild they were using some type of bronze insert, would have like to seen more from the machine shop, no umbrella seals available ?

Bronze liners are still in wide use jerry. I am not sure where you heard that. It just is not accurate. I have a head getting liners done as we speak. I have run them on the street for 40 years and not one of my machinists has ever told me they were a race only item. They have been used on street rebuilds for decades.

I installed full bronze guides for a lot of years on the race engines I built, especially on the heads with double and triple springs, and taught liner installation 20-something years ago when they were popular. Now they're practically giving the liners and installation tooling away on Ebay because they're so obsolete. None of the machine shops in the middle Tennessee area where I live will even talk about installing liners- - - -too much labor cost for the prices they can charge.
Jerry

That may very well be in your neck of the woods but bronze liners and Teflon seals are still a very good alternative to the old rubber o rings and umbrella seals. And yes, they were and still are used on race engines but never exclusively. They work for street Motors just as well. The fact is that a lot of shops don’t have a lot of need, particularly if they are building the more common motors like a small block Chevy primarily because there is no real call to rebuild old GM head castings. The quality and airflow of the aftermarket heads currently on the maket is so good it’s simply not worth rebuilding an old head. But for those of us who are rebuilding the more odd ball motors, rebuilding an old head is a necessity and for my money, bronze liners and Teflon seals are a vast improvement over the O rings and umbrella seals. It’s just an alternative.

does a 216 use O rings on the stems or umbrella seals ?

The o-ring type seals were used.

But, maybe someone will comment about the umbrella seals?

I think Jim Carter sells both styles together.

I'm not a fan of the umbrella seals. These used to be really good, but the ones out there today last about a year or two at best. Once they crack and split, you're left with no seals. And Jerry's comment about not using both is spot-on. You don't want to starve the valve stems of lubrication. Personally I use the o-ring type and leave it at that. I think I paid $1.80 for a set of 12 from Rock Auto and if you catch them on a mfg closeout offer, they're about 8 cents each.

x2 on the umbrella seals. They were really the improvement over the O rings when rubber was real rubber. So if you had some worn valve guides, and were willing to remove the springs with the head in place, you could install the umbrella seals and get a little better control over the oil intake down the valve stem.

These days the rubber is not what it use to be and deteriorates pretty quickly. In my experience, the O rings are unfortunately in the same boat. I have taken a couple of dozen 235s apart over the years and truth be told, to this day, I have never found a single intact O ring on any of them. Then the Teflon seals came on the scene.

With a good fit between the guide and Valve stem, the o rings get the job done for as long as they are intact. After that, your burning a little bit oil.

Mike have you ever used square viton o-rings?

Jon, I haven’t. Primarily because I have had really good luck with the pc style seals over the years. On the other hand, I assume you have? How did they work out? Durable?

I've had good luck with a seal design that clamps onto the top of the valve guide with a flat spring and has a Teflon insert that rides on the valve stem. It's not as compact as the tiny P/C style seal that requires the top of the guide to be machined down so double or triple springs can be used. It's a good compromise between the umbrella seal that's supposed to ride up and down with the valve stem and the racing-type seals. As above, if that type of seal is used, don't use the O rings.
Jerry

Mostly I'm curious, Mike. Years ago these were used on a head re-done by a man who was the best valve fellow in Dallas. He passed away prematurely, but when I removed that head (rebuilt around 1976) a couple of years ago, they were still fine. Don't most of the pc seals use viton or ptfe?