Type of Valve Seals for Small Block Chevy - Team Camaro Tech
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post #1 of 5 (permalink) Old Jan 16th, 06, 11:33 AM Thread Starter
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Question Type of Valve Seals for Small Block Chevy

My local machine shop recomends using umbrella type valve seals on the exhaust valves and posi-locks on the intake valves. I've always been afraid these seals would starve the guide for oil, especially the posi-locks and get a shorter life out of the guides and valves. I'd like to hear some other opinions. Thanks.

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post #2 of 5 (permalink) Old Jan 16th, 06, 12:00 PM
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Re: Type of Valve Seals for Small Block Chevy

My 2 cents worth is , if you are afraid of using those after market type seals, make sure your valve guides are in excellant shape and use the factory style O ring. The positive seal style that I am used to using have a teflon seal on them and seal well but guide boss has to be milled to fit.

The old "Ford" unberalla style gain some use as they would not necessarily need boss milling and would help prolong the use of the guides if it was worn or worn consideribly. So the choice is yours,, your head shop is just trying to do you a favor in turn, but guides need to be in good shape either way.

True the exhaust needs more lube due to heat but the factory style O ring will do just fine, depending on your applications and useage. Intake side needs a good seal especially when hi mileage comes along.

If you ever consider Wionna Bronze guide inserts, they also work well and can be replaced easily but you need to have the insert tool. Another method is the bronze sleeve or guide.. Choice is yours.

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post #3 of 5 (permalink) Old Jan 16th, 06, 02:39 PM Thread Starter
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post #4 of 5 (permalink) Old Jan 16th, 06, 05:03 PM
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Re: Type of Valve Seals for Small Block Chevy

We have been positive type seals on both intake and exhaust for quite a while now. All of the new cars come that way and they dont seem to have any problems. The more oil you keep out of the combustion chamber the better. I think that valve materials are a lot better than they used to be and even most stock valves have chrome stems, minimizing any risk. I have been using the metal cased positive seals like come on the Vortec heads on almost everything. I would bet that since 1987 when I started in the machine shop business, I have probably only seen 5 or 6 "stuck" valves.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md
1971 Chevelle "Heavy Chevy" original owner

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post #5 of 5 (permalink) Old Jan 16th, 06, 06:00 PM
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Mike Rogers
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Re: Type of Valve Seals for Small Block Chevy

As bill stated most if not all new cars come with a positive type seal.They have a metal outer jacket and vinton rubber for the seal.

I don,t hardly use any teflon seals any more. There is also the 2 ring all rubber seal that you will see also.

Also as stated you will have to cut your guide boss for these seals to work.

Some chevy heads are done from the factory and use a .562 seal were as most other ones will be .500 to .530 guide boss.

If you look at the link below it will show you the diffrent type of seals Bill and i would use in an engine.

The 1st. would be factory
2nd unbrella type mostly used for quick fix.
3rd 2 ring rubber type may or may not have to cut guides found on factory heads.
4th teflon type used for along time in racing must cut guide boss.
5th type used by most manufactures today may or may not have to cut guide bosses. This is the type seal i like to use.



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Last edited by Rogers Performance; Jan 16th, 06 at 06:16 PM.
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