valve seals

[lcfman]

I have a Chevrolet 348 that I need to replace the valve seals on. My problem is that the head shop I sent the heads installed umbrella type valve seals and they are failing due to the OD of the valve stem boss is .855 and the ID of the umbrella seal is .600 and after a few cycles the umbrella seal being forced over the boss is causing the seal to fatigue and split into. I understand that the valve stem boss should have been machined to accept positive valve seals but I want to try to solve this problem without taking the intake and heads off. Are there any positive valve seals available for such a large boss? Is there another fix? Your comments are appreciated.

[Scotty]

Felpro seals out of a ford cleveland gasket set have 8 bucket shape seals and 8 short umbrella shape seals these shorter seals might get you out of trouble,try your local machine shop they may have some kicking arround due to upgrading to positive type seals.

[fdicrasto]

Is the .855" boss fully machined or are they as cast?

[mag2555]

Cutting the guides for positive seals with a cutter may be able to be done with the heads on the motor since those valve guides are so long on those heads!

[lcfman]

The bosses are not machined but as cast.

[jcisworthy]

I have some umbrella seals that are .750 id and slide on a .850 socket snug. About .850 tall for 11/32 valves

They came in a full set for a mid 90's 302 Ford

[lcfman]

Looks like that seal might work unfortunately my valve stems are 3/8' s.

[jcisworthy]

I have a bag of AMC seals. 3/8 valves, .700 high, .850 or so ID. I slid one on a socket around .860 and it goes on with some press. They may work for you.

Send me a pm if you want them I will send them to you.