Valve Stem Seals
Thread Starter
Melting Slicks
Joined: Feb 2003
Posts: 2,330
Likes: 6
From: Long Island NY
Valve Stem Seals
I know it's been posted before, but here it goes again. What's the best seal for a stock '78 L82. I need brand & part number, because there are to many choices. Many have said the 'umbrella' is best for stock...
Drifting
Joined: Apr 2003
Posts: 1,323
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From: Castle Hills Texas
Intermediate
Joined: Jan 2004
Posts: 42
Likes: 0
From: Roswell GA
GMPartsDirect sells the thick walled rubber, posi-lock type used on ZZ 350 series engines (PN#460483 I believe). They do not require machining guides and work very well but are over $2 ea. I couldn't find the Crane of same type and heard they were
out of production.
out of production.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
NAPA has umbrella seals.
Originally Posted by mvftw
I know it's been posted before, but here it goes again. What's the best seal for a stock '78 L82. I need brand & part number, because there are to many choices. Many have said the 'umbrella' is best for stock...
Mine were Pioneer brand and dirt cheap. Bought'm from PAW but can't recall the part #. NAPA carries the same thing.
cardo0
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Le Mans Master
Joined: Sep 2003
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From: eastern NC
Vega Valve Seals - The last time I purchased a set, was in the early 90's. I can't remember who made them, Hastings, Fel Pro, TRW, but they were made of "Viton"... read on...
In the mid-1980s, positive valve stem seals made of fluoroelastomer materials (FKM and Viton) began to appear in import and domestic overhead cam engines. Fluoroelastomer seals cost roughly 12 times as much as nitrile, but have a temperature range of -5º to 450º F, making them one of the best high-temperature seals available.
Viton has good flexibility like nitrile, which means it can handle some runout between the valve stem and guide. It is also considered to be a more durable material than silicone. Viton also has better wear resistance than most other seal materials, making it a good choice for applications where long term durability is a must.
The highest rated positive seal material is Teflon, with a range of -5º to 600º F. Like nylon, Teflon is a hard material so it cannot handle as much runout between the stem and guide as more flexible seal materials can. What's more, Teflon is expensive - costing 20 to 25 times as much as nitrile.
GUSTO
In the mid-1980s, positive valve stem seals made of fluoroelastomer materials (FKM and Viton) began to appear in import and domestic overhead cam engines. Fluoroelastomer seals cost roughly 12 times as much as nitrile, but have a temperature range of -5º to 450º F, making them one of the best high-temperature seals available.
Viton has good flexibility like nitrile, which means it can handle some runout between the valve stem and guide. It is also considered to be a more durable material than silicone. Viton also has better wear resistance than most other seal materials, making it a good choice for applications where long term durability is a must.
The highest rated positive seal material is Teflon, with a range of -5º to 600º F. Like nylon, Teflon is a hard material so it cannot handle as much runout between the stem and guide as more flexible seal materials can. What's more, Teflon is expensive - costing 20 to 25 times as much as nitrile.
GUSTO
Thread Starter
Melting Slicks
Joined: Feb 2003
Posts: 2,330
Likes: 6
From: Long Island NY
I e-mailed Eledbrock about using the Viton seals on a stock motor and they recommend NOT to! So if somebody can verify that the ZZ350 uses the same seals as my L-82 (rubber type) I'm in business...
Intermediate
Joined: Jan 2004
Posts: 42
Likes: 0
From: Roswell GA
mvftw...I'm no guru but I was under the impression pretty much that all stock Chevy SB's had 11/32 inch valve stems(guides similarly) even aluminum heads or different valve sizes. These posi's are flexible with tension collars & will accomodate slight variations). I don't know what the L82 came with. My 74 L48 had umbrellas and no O'rings. I can't believe some of the guru's here haven't chimed in - must be busy getting their cars ready for spring. Have you emailed or
phoned customer service at GMPartsDirect, Scoggins etc? They should be able to tell you what you need to know. That price for four is much cheaper than what I paid before I found GmPartsDirect. Good luck..
phoned customer service at GMPartsDirect, Scoggins etc? They should be able to tell you what you need to know. That price for four is much cheaper than what I paid before I found GmPartsDirect. Good luck..
Tech Contributor
Joined: Aug 1999
Posts: 15,136
Likes: 3,939
From: Connecticut, USA
The stock engines used O rings, not sure if they used the umbrellas?
If the guides are good the O rings will work until they wear or break should be many thousands of miles. The umbrella offer more coverage and work better then the O rings. I think the concern is if you have a HV pump or tighter valve springs that would interfer. If the HV pump fills the head and gets above the boss to the guide the oil will go down the guide. The positive seal may/may not requre guide boss facing, I think most do but there were soem Crane seals mentioned here in the past that didn't.
All said and done I'm using the umbrellas in the engine I'm building now. I have WP Torquer heads and the valve don't have the groove for the O rings anyway.
Gary
If the guides are good the O rings will work until they wear or break should be many thousands of miles. The umbrella offer more coverage and work better then the O rings. I think the concern is if you have a HV pump or tighter valve springs that would interfer. If the HV pump fills the head and gets above the boss to the guide the oil will go down the guide. The positive seal may/may not requre guide boss facing, I think most do but there were soem Crane seals mentioned here in the past that didn't.
All said and done I'm using the umbrellas in the engine I'm building now. I have WP Torquer heads and the valve don't have the groove for the O rings anyway.
Gary
