avst03

Hi

I have a Chev 350 with 462624 heads built in 82, doesn't have separate valve guides. The guides are part of the casting.
It came from the factory with o-ring seals on the valves.
Intake valves have 11/32" stems and the exhaust have 3/8" stems.

My questions are:

-Can I use o-rings with umbrella seals?
-Which materials hold up well ie: viton, silicone, nitrile etc...
-do the umbrella seals move with the valve, or are they stationary.

Thanks
Mike...

sofakingdom

iTrader: (1)

Valve guides are .500" OD, cast iron, and press into the heads. The part that sticks up out of the head is usually more like .650" OD.

I have NEVER, in all my days, seen a SBC with 3/8" valves. Not that such a thing doesn't exist; just, you'd be like the ONLY person on earth that has non-stock valves like that. Pretty low probability. More likely you're looking at exhaust valve rotators.

Umbrella seals ride up and down on the valve stem. They're not just super effective. Better than just the O-rings, but still pretty lame. Yes you can use O-rings with them, since the unbrella seals go on the valve stems BELOW the retainer, but the O-rings go on ABOVE the retainer, that is, you put the retainer on, then put the seal in the lower groove, then put the keepers on in the upper groove, and the retainer comes back up when you release the spring compressor and seals around the outside of the O-ring; but there's no particular reason to do that. All they do is keep oil that gets on top of the retainer from running down the valve stem.

Best kind is the "positive" ones made from Teflon that grab onto the guide and stay put, and fit tight to the valve stem. Those require machining unfortunately however.

The FelPro "premium" ones might work on your heads. Probably not, but who knows, you might get lucky. I believe they'll fit over anything from about .625" up to around .640". I believe they'reViton, but it hardly matters; they're what's available, that might work. A "take it or leave it" situation.

avst03

Thanks for the reply sofakingdom

If I rebuild the head I'll switch to positive type seals, the area a positive seal would fit is .560 on the exhaust and .550 on the intake

The exhaust valve stems are 3/8” I measured them with my digital vernier caliper:-)
I found some hi-temp 3/8" silicone umbrella seals in Victor Reinz part# B45779

Has anyone found online catalog for Fel-Pro gaskets or a pdf cat

Mike...

sofakingdom

iTrader: (1)

Well congrats, you've got the only one. try www.partsamerica.com

You don't REALLY need seals on the exhaust.

You REALLY REALLY REALLY don't need to be spending A DIME on those heads. They are the trash.

chesterfield

Never?

avst03

Your right about the heads!
My engine was built during the darkest days at GM for performance its a 160hp 350 in a 1 ton class C motorhome G-series Van loaded up weighing in at 10000 lbs on most trips. I only posted on Third Gen because I thought the GM truck sites didn't have much engine info.

Mike...

sofakingdom

iTrader: (1)

Well, with that guide diameter, there are no "positive" seals that will work, that I know of. So you're stuck with umbrellas at best.

I wouldn't fool around too much with exhaust ones; although you can just get some for a big block and they'll work, since that's the std valve stem size for BBC. Concentrate on the intakes, if they leak oil.

Then start saving up your spare pennies for some heads.

avst03