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Old 11-26-2008, 07:11 PM
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viton seals

Hey guys I am rel confused about these seals right now... I ordered some for my vortec heads.... When I told my machineis about the seals I bought he said, "you'll be sorry". I thought Viton was the best you could get, but He swears that they "eat up valves"... He said I should just use the positive seals that come with my gasket kit, and they'll do just as good, and wont eat up my valves...
Is this true or is he FOS??? I dunno I need some advice!!

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Old 11-26-2008, 07:32 PM
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Well, if you have a fresh set of heads you probably dont need anything other than the stock stuff. I've used them on well worn chevy small blocks and it's helped to slow down the amount of oil that gets by the guides. I used them on a new set of Sportsman heads that I put together for my boat and ended up seizing an exhaust valve due to lack of lubrication. Intakes aren't a problem since the gas helps lubricate the stems, but the exhaust, if your dead set on running them I'd assemble the heads without any seals on the exhaust and put them on after they've had a while to break in.
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Old 11-26-2008, 08:01 PM
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Umbrellas are better for street engines with tight clearances on the valve stems, as they are when fresh.

Positive seals are better for race clearanced valve stems. There is a lot of hype in the magazines about positives being better but the reality is umbrellas are more practical.

Thats why the factories use em.
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Old 11-27-2008, 06:29 AM
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clearanced

well, the heads are being clearanced att the wat down to the deck for 3 reasons.
1. my cam is 525/546 lift for now
2. In the spring after tax time I plan on switching to a retrofit H roller cam w/ 600/600 lift from doug herbert
3. the ID of the aftermarket PBM springs I bought is only .785 with damper, which wont fit over the guide boss in stock form.

This is why I planned on using a posi seal, but I just don't know weather I should use the Viton's or the other ones that come in my gasket kit???
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Old 11-27-2008, 09:33 AM
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eatonde,
in your other seals thread you said the motor shop "told you!!!!" to buy viton seals and you wanted to know why?????

(which is principally/usually centered on the springs choice and second the rockers used)

if you look which seals are used on assembled after market heads:

http://store.summitracing.com/egnsea...15&Nao=0#rstop

some are umbrella seal
some are viton (trick flow/afr/patriot/some summit/etc to name a few)
some are teflon (brodix/FRPP/etc)

study the heads on the link to find the ones closest to yours for lift and springs and rockers to figure out if the engine shop is full of BS....
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Old 11-27-2008, 02:16 PM
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valve stem clearances, guide type, seal type, springs, etc. all should be chosen and installed as a system.
hodge podging stuff together is not a good plan.

If you don't/can't trust your head man, then go find somebody else you do trust. period.

10 years ago when I was still in the engine shop everyday, customers gave us their goal and we built it our way- not theirs. If they didn't like that, I suggested that they go somewhere else.
IT IS OUR REPUTATION ON OUR PRODUCT. Nobody is going to care what the customer wanted if it fails to perform. All they see is that it came out of my shop.
period.

Many new engines use positive seals..... its a smog thing.

Last edited by ScoTFrenzel; 11-27-2008 at 02:22 PM.
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Old 11-27-2008, 02:33 PM
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I would never use a shop that didn't let me plan my own build. Sure they should speak up if they think something is wrong, but the final say should always be the customer's. Now, if a customer has no idea what they are doing that is a different story, bt if they have a set opinion on how something should be then you should educate them on your POV and then do it their way.

If I'm paying for it then I want it up to my standards. Just as when I do something at work it is what the customer wants, not what I want to give them.

I understand many shops don't do that and are still in business. And there are many shops that do listen to a customer and they get free advertisement from a more satisfied customer.
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Old 11-27-2008, 02:42 PM
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Quote:
Originally Posted by ap72
I

I understand many shops don't do that and are still in business. And there are many shops that do listen to a customer and they get free advertisement from a more satisfied customer.
And from a DIS-satisfied customer.
A customer will NEVER admit that he botched the specs or insisted he wanted it done HIS way period...

the unhappy customer ALWAYS blames the shop/assembler.
I don't need that.

We built thousands of engines, and hundreds of winners,
stood behind every malfunction, and ate a few we shouldn't have....
and had the reputation of being a quality shop to trust and rely on.

10 years ago is ancient history.
That head man is still there, and I think he is still as good as anyone in the USA.

Last edited by ScoTFrenzel; 11-27-2008 at 02:47 PM.
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Old 11-27-2008, 02:58 PM
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Quote:
Originally Posted by ap72
I would never use a shop that didn't let me plan my own build. Sure they should speak up if they think something is wrong, but the final say should always be the customer's. Now, if a customer has no idea what they are doing that is a different story, bt if they have a set opinion on how something should be then you should educate them on your POV and then do it their way.

.
Agreed. Communication and discussion.

The subject we are discussing, seals, valve set up...... very few, very few customers have even the slightest idea what the whole thing is all about.
They don't understand clearances, guide materials, oil requirements/seals, valve rock, rocker arm dynamics, etc.

so those customers have next to zero valid input.

In fact, I ask, why should they care about any of the technical stuff just as long as their engine performs well and gives them good longevity and service?

Just trying to communicate my ideas
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Old 11-28-2008, 02:05 PM
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viton seals

Redmustang.
In the other thread, I may have said that, but I think I mis-understood him. He did say to use a posi seal, and I thought he meant VITON, but I guess he didn't. I told him that I bought posi viton seals and he just said thats the worst thing I could do... He says that viton isn't good for STOCK valves, yes many aftermarket companies use them, but he said they have better valves in them. He said if I replace the valves then go ahead and use the viton, but it'd be a mistake with stock ones cuz the "eat up the stems"!!!

I'm no pro, thats why I'm askin if this is true about the viton's.... I know the big name heads use them, and thats why I got em, but he says thier really hard on stock valves
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Old 11-28-2008, 10:59 PM
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he gave you a pretty honest answer....

the "ductile" properties of a "stock" "made in China" valve used at higher than designed for temp and rpms is not the same as a performance valve for expansion growth or flex....

a performance cam makes all kinds of truly weird movements and loads happen in the valve train....
a soft stock valve has to have tight stem to guide clearance for stability to survive....
buy more "stable" valves designed for the higher heat and rpms and you can use viton seals...

not enough oil on the stem due to a viton seal can cause a tight clearance stock exhaust valve to actually seize and the motor will go Kaboom

bottem line:
you can replace the inexpensive valve stem seals with the heads on the motor later on if/when needed so follow his directions....
plenty of "how to's" on the web, it's not rocket science and many parts stores have a "loaner" spring release tool....
buy the seals he recommends,,,,hell of alot easier and cheaper to replace the seals than pull the heads to replace the valves is the point I think he is trying to get across....
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Old 11-28-2008, 11:58 PM
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Your getting some good advice Eatonde, you need to understand why viton is used as opposed to the other types.

Your valvetrain can comprise many different materials.

Valves can be machined from stainless, titanium or high carbon steel.

Guides can be stock cast iron, bronze...even brass inserts have been used.

Bronze on carbon steel is a good lubricating pairing, they need little oil to work well and can be run at tight clearances. Carbon steel on cast iron is almost as good.

Stainless on Bronze is less tolerant and needs a little more clearance to work properly.

Stainless on cast iron is the worst and needs more clearance since the expansion characteristics are different and cast iron isn't a good wearing partner with stainless...nothing is to be honest.

Viton seals are used on large clearance race engines where they need to seal the oil from leaking by the large clearances, typically these engines would also have bronze guides and hence don't need a lot of oil anyway.

Teflon can be used on almost anything as they pass oil well and don't seal as positively as Viton.

Like everything it depends on usage, if this is a street engine you would be better off running tight valve stem clearances with either bronze guides or cast iron guides with teflon seals or umbrellas...leave the vitons for the race engines that need them.

Personally I am a big fan of Ford Style umbrellas, they are just about full proof for anything short of a race engine...they need no special machining and best of all they are cheap like dirt plus ensure you don't have any problems with lubrication of the valve stem at high temps like you might see sitting in stop and go traffic on a hot summer day.

Teflons are great too but need the guide tops machined plus they wear out over time, umbrellas get brittle over the years too but compared to a fixed guide seal they are foolproof and longer lasting.
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Old 11-29-2008, 07:28 AM
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The shop I used to work at had written warrenty that stated if we build your engine they way "YOU" want us to, we guarantee the engine be incorrect. Then he would write down what will happen.. Like the guy that comes in with 12.5 to 1 pistons and 62cc heads and is going to run regular unleaded gas, he will wirte down "this engine will rattle it self apart, blow top rings lands out blow head gaskets, etc" And he would have them sign it. You would not beleive how many times this has saved his butt.


Quote:
Originally Posted by ScoTFrenzel
valve stem clearances, guide type, seal type, springs, etc. all should be chosen and installed as a system.
hodge podging stuff together is not a good plan.

If you don't/can't trust your head man, then go find somebody else you do trust. period.

10 years ago when I was still in the engine shop everyday, customers gave us their goal and we built it our way- not theirs. If they didn't like that, I suggested that they go somewhere else.
IT IS OUR REPUTATION ON OUR PRODUCT. Nobody is going to care what the customer wanted if it fails to perform. All they see is that it came out of my shop.
period.

Many new engines use positive seals..... its a smog thing.
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Old 11-29-2008, 08:52 AM
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eatonde,
while looking for something else I tripped over this seals article:

http://books.google.com/books?id=TcN...esult#PPA80,M1

I forgot to mention,,,
part of the reason he wants posi-seals is the longer cam event means there is air pressure for a longer period on the exhaust valves guide clearance as the piston moves up....
the piston is literally trying to blow the oil back up into the heads....
a umbrella seal moves with the valve so more oil can go up the clearance and more exhaust will get into the pcv...

my $.02
it's a impossible balancing act for oil quantity versus seal performance and life on the stems when using stock heads and valves that weren't engineered for more btu's and duration and more lift and more rpms cams....
as always in hot rodding, to get something you will give up something....
I am a fan of viton seals because they are way more heat degradation resistant,,,buna-n degrades at around 250*F ,,,viton is happy till 450*+,,,when you turn off the motor there is no more oil cooling flow over the seal and hotter than stock stationary stem...
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Old 11-30-2008, 10:37 AM
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Quote:
Originally Posted by mitchc
The shop I used to work at had written warrenty that stated if we build your engine they way "YOU" want us to, we guarantee the engine be incorrect. Then he would write down what will happen.. Like the guy that comes in with 12.5 to 1 pistons and 62cc heads and is going to run regular unleaded gas, he will wirte down "this engine will rattle it self apart, blow top rings lands out blow head gaskets, etc" And he would have them sign it. You would not beleive how many times this has saved his butt.

and as this thread has expounded, there are many variables that affect the overall performance of seals.
Again I state....... "chosen and installed as a system"

and...."If you don't/can't trust your head man, then go find somebody else you do trust. period."

and Sir, YES it probably saved his butt, as you said,,,,,,,,,
but I would bet that those customers did NOT go around telling all their friends that it was THEIR FAULT.

That machine shop man was correct in what he did
but he still got negative publicity from the failures. Like it or not.

thanks for all the tread input.
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