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I'm changing valve seals on a young guys 1994 Chevy truck with a 350. Ordinarily, I wouldn't have anything to do with a Chev, but his dad was a good friend of mine, and he died a year ago, so I offered to help. My question is...can I use the same seals on the exhaust as the intakes? The parts guy told me the book just showed the little o-ring below the locks on the exhaust, and nothing else, and I'd already pulled one and it had an umbrella seal on it, so I grabbed 2 sets of intake seals. The only real difference I can see is the intake seal has a metal band around it, and the exhaust doesn't.
I know this sounds like a retarded question, but I've never worked on a Chev before. And hopefully never again. You can't put a wire in the spark plug hole to feel for the piston because the plug lays so flat, you have to grind the AC compressor bracket bolts half off to get them by the clutch because the valve cover can't get by the compressor, there's no fender relay for the remote starter switch... :roll:
 

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The seal with the metal band around it, is a positive type seal, not an umbrella. They push down over the O.D. of the valve guide. The exhausts still use an umbrella type (usually made of white teflon, or orange silicone due to high temps), as the oil atmosphere better lubricates the hot running exhaust valve stems.
 

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The thing that has me confused is the exhaust seals are fitted onto the guide too - just like the positive type seals. Thanks for the replies guys. I'll go back in and work the parts guy over again. :wink:
 

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John I. said:
The thing that has me confused is the exhaust seals are fitted onto the guide too - just like the positive type seals. Thanks for the replies guys. I'll go back in and work the parts guy over again. :wink:
If both sets of seals are the positive type, there is definitely a difference between intake and exhaust. Primarily in seal material. Personally I would never use a positive seal on SBC exhaust valves. They run too hot and tend to wear out even with the oil saturated atmosphere of umbrellas. The positives are great to use on the intakes, but on the exhaust, use a teflon umbrella, and your OEM o-ring seal as well. Don't forget to use the little plastic installation sleve when sliding the seals over the valve stems, as the lock grooves can damage the sealing surface. Good luck!
 
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