[Jack Gifford]

Yeah, as "OK" as they were in 1955- when a certain amount of oil consumption was "normal", and Pontiac even added intake guide vacuum-bleeder holes to band-aid the situation.

[MJVAUGHANS]

JACK,

These seals were on the guides when the heads were disassembled. Are these junk? Will they work?

https://www.summitracing.com/parts/cca-504-16/overview/

[Jack Gifford]

I haven't used the Comp Cams seals. They apparently are intended for use on as-cast (unmachined) guide O.D.'s? Do they grip the guide tightly? Many non-Pontiac engines used that style seal, and usually I'd find the seals joy-riding on the stems- no longer even touching the guides. Machining the tops of the guides for modern Viton seals (with built-in spring clamps) is a more reliable solution.
Having said all that; the Comp Cams seals might work okay for you.

[MJVAUGHANS]

I cannot quote where I saw it, but somewhere on the internet I read a comment about these being umbrellas and their purpose was to deflect oil from the guides and they did not have to stay solidly attached to the guides because their job was not to wipe 99.9% of the oil off. Some oil was needed for lubrication of the valve? I do not know.

[mgarblik]

Yes those seals you show from Summit are typical unbrella seals. Used by many manufacturers as OE, but not much by GM. Ford used them allot. They fit on the valve stems and ride along on them deflecting oil much like the O-ring and sheet metal shield set-up Chevrolet and many Pontiac engines use OE. They are OK, I guess. A positive seal that fits tightly on the guide is better but requires machining. If the heads are on the car, umbrellas are fine. If the heads are off, machining for positive seals is fairly inexpensive and they do work better.

[MJVAUGHANS]

Heads are not on yet, but they of course would have to be stripped back down, again, for machining. I am just afraid how long it would take for the machine shop to cut them down. Also, I see different seal types so which ones would I use?

[Jack Gifford]

Cutting the guide OD's for seals takes little time. If you want to remove/reinstall the valves yourself, I'll loan you the Crane cutter that I bought in '59. You just need a 1/2" portable drill, since it pilots into the guide.
All brands of Viton seals I've used were good quality.

[MJVAUGHANS]

Originally Posted by Jack Gifford

Cutting the guide OD's for seals takes little time. If you want to remove/reinstall the valves yourself, I'll loan you the Crane cutter that I bought in '59. You just need a 1/2" portable drill, since it pilots into the guide.
All brands of Viton seals I've used were good quality.

I think I am going to talk to the machine shop about it before I try it myself. But I do appreciate the offer. If I did not have so much going on already I would not be afraid to do it though.

[mgarblik]

As Jack said, it is a simple operation and can be done with a hand drill. A seat and guide machine is a little faster and probably a little more accurate. If your machine shop has a .530" cutter, I would use that size. It leaves a little more material around the top of the guide. But .500" is fine also, if that's all they have. Buy the right size seal and you are in business. They are much more effective than umbrellas and O-rings.

[MJVAUGHANS]

Originally Posted by Jack Gifford

Cutting the guide OD's for seals takes little time. If you want to remove/reinstall the valves yourself, I'll loan you the Crane cutter that I bought in '59. You just need a 1/2" portable drill, since it pilots into the guide.
All brands of Viton seals I've used were good quality.

Jack,
Is your cutter .500 or .530 ?

[Jack Gifford]

PM sent.