Hey guys, I have a 1990 Formula L98 with 127,000 miles. My dad purchased the car in 1995 with 29,000 miles and always, on initial start-up, it has coughed it's usual puff of smoke. Well, it's time for me to fix it and I want to know the best combination of valve seals. What are the best to use? I've heard viton seals are great, but what do you guys think? I am thinking of both, some type of positive seal and o-rings on both intake and exhaust valves. Any advice would be greatly appreciated. Thanks

 

Umbrella seals can be installed with the heads on the engine. Other positive seal types have to have the guide machined, and that must be done with the valves remove, so that means the heads off.

Viton is better than Nitrile (also called Buna-N) for high temp resistance, so that would be a good choice. I would recommend using both the o-ring and umbrella on both intake and exhaust like you indicated.

If this car has been doing this since 29k miles and only 5 years old, that doesn't sound like typical valve seal wear/hardening. But, it could be. What color is the smoke?

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82 Berlinetta, orig V-6 car. Rescued w/86 LG4/TH700R with all harnesses, sensors, ECM, etc. 2.73 open. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LB9 w/ZZ3 cam, ported heads, exhaust, paint, etc.).
57 Bel Air, my 1st car. Currently 396 .030 over, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & shift kit, 3.08 10-bolt, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

 

The smoke is a bluish-white commonly associated with buring oil. It seems to smoke most if you drive it, get the oil hot, shut it off for a few hours and start it again. I think the oil may be rolling down the guides and into chambers. What's strange is it doesn't burn any oil. I've seen it on many TPI 3rd gen cars. I was told by my buddy, who is a GM techinician and the SBC specialist at his dealership, that some of the TPI cars never came with a seal on the exhaust side and they would smoke from day one. He said this was very common with the truck heads as well.

Ok, any ideas where to purchase the viton umbrella seals and what they might cost?

 

If you don't get smoke upon deceleration (if that's a word), then it could be just your exhaust and wouldn't be a problem when running, therefore not a consumption problem.

Try NAPA, Big A, most any "good" parts store for the seals. Don't be surprised if you get blank stares at first, just ask them to keep looking. I have a brother in Omaha who's going to be doing the same thing soon. I forget which store he normally goes to, though.

 

i use both, comp cams umbrella seals and the factory o ring type seal.

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