Max

I'm in the process of replacing my valve springs and I have found that all 16 valves are fitted with umbrella style seals. They seem so be in good condition but my valve stems do not have a provision for o-rings so that's all I have for valve seals.

Would it be worth the additional expense ($40 approx.) to replace the flimsy umbrella style seals with the (rubber w/metal clamp) positive style seals? I have read on TGO that some people use the positive seals on all sixteen valves. Is that a good idea?

The manager at my local machine shop said that the bosses have to be machined to accept positive style seals. Is that true? I thought that was only if you were using the teflon positive style seals.

five7kid

iTrader: (14)

There used to be a type made by TRW that didn't require machining, but the last time I tried to get some, they weren't available.

Of course your valve stems have provision for o-rings. Doesn't hurt anything to put both the o-rings and umbrellas on.

Max

I had these heads built by a machine shop a few years back and I paid for a new set of back cut, swirl polished, stainless valves. I have been thinking that he had ripped me off and charged me for new valves without actually installing them. But now I find that the valve stems have only one groove so maybe he really did install the aftermarket valves I paid him for. In any case I don't think I can use o-rings without a second groove.

5.7 Kid - are you saying that the rubber positive seals do require machining the bosses? I have been thinking that a lot of stock heads came with them on the intake valves at least.

Will the umbrella style seals hold up and keep the engine from smoking on start up?

sofakingdom

iTrader: (1)

Problem is, there's ALL SORTS of sizes of stock valve guides; so there's no way to make one seal that fits them all.

The FelPro ones usually fit most of the heads that came on these cars though.

Intakes are by far the worst offenders. The FelPro seals won't last a real long time on the exhaust anyway. Just put them on the intakes. They're about $15-18 a set IIRC.

Damon

I beleive 081 heads came from the factory with positive seals on both the intake and exhaust. If I'm right, there should be a necked-down top part on the valve guide boss about 1/2" tall, then it gets fat below that. If you see that's the case then using a set of push-on guide seals such as you describe should be a no-brainer as you're already set up for them. If I'm right up to this point you'll induge me further when I tell you that they'll take seals designed for a .530" valve guide boss diameter.

Sonix

iTrader: (1)

Yea, Apeiron wrote a pretty good post in the TPI forum I think, on how he put positive seals on all 16 spots on his LB9 headed car. Pictures, etc, a nice how to thread. See if you can find it, i'm sure he posted the part #, it's a felpro part, with a lot of 7's in the part number