Yesterday we started pulling the valves from my friends 302 heads. They are almost identical to a Chevy setup except for the rubber umbrella seal thingy. Could these be installed on a chevy to stop oil from going down the valve guides?

Also, what would it mean if there is carbon buildup on the backside of an intake valve? The #1 intake valve had alot of crap on the part opposite the valve face.

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1983 Firebird
TH700R4 Auto
Small Block 400
LG4 ECM, Intake, Carb, Distributor, etc.
Soon to be non-computer.
Clarion Head Unit 45X4
2 Pioneer 400W 12" Subs
Third Gen Performance
"A four cylinder is half an engine."

[This message has been edited by Ward (edited April 05, 2001).]

 

I've seen posts here recommending the umbrella type, standard type only, and even both at the same time. Carbon buildup is typically associated with a rich fuel/air mixture, but deposits could also be the result of a leaky seal.

 

from my experiences the umbrella type seals leak a bit more oil than the standard seals. many people use them because they dont rub the valve which means less friction. i prefer the fel-pro "viton" seals personally.

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85 IROC 350 11:1keith blacks,.555lift erson roller cam,1.5 crane roller rockers,edelbrock intake,holley 4150 750dbl pumper, nitrous oxide,full length heddman headers,true dual exhaust, 11"stall converter, 700R4, 3.73 locker

 

Yes, you absolutely CAN use them on a Chevy motor. I do it all the time becuase assembling the stock Chevy o-ring and shedder is a PITA and doesn't work all that well to begin with.

Personally, I use umbrellas on the exhaust becuase, like was said above, they don't seal things up super dry and the exhaust valves can use the extra oil. On the intakes I use the push-on posi seals that hold onto the valve guide and have a tight positive seal against the valve stem. They seal things up pretty dry.

Interestingly, many later Chevy heads come standard from the factory with these posi seals on the intake IN ADDITION TO the old o-ring and shedder arrangement.

 

An umbrella seal that fits over the guide will seal much better than the o-ring alone. I wish I had bothered to replace the exhaust when I put the umbrellas on my intakes, but just doing the intakes lowered oil consumption significantly. The positive type seal that requires machining the guide are the best for the intakes, like Damon said.

The carbon deposits are from oil, either leaking down the guides or from the intake gasket. Possibly a PCV system that's sucking oil.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam and intake, World 305 heads, Hooker headers & y-pipe, 3" Catco cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

 

i use both umbrella and o ring seals when i do heads

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ICON Motorsports

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