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Thread: valve stem seals: o-ring vs. umbrella?

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    Default valve stem seals: o-ring vs. umbrella?

    So last week I dismantled both a pair of e7te heads, which will go on my old engine and were also for practicing on, and a pair of gt40 heads for my new engine build.

    Both were probably never worked on-- or if they were, it didn't show ;-)
    So both types of heads from the factory had o-ring type seals on both the intake and exhaust valves.

    When my parts came, it was evident that they wanted me to put oring seals on the intake, but umbrella type seals on the exhaust valves.
    What's the practical difference?

    Now, I didn't realize that a gasket kit comes with valve stem seals so I'd ordered a full complement, and I have 2 sets of seals- 16 oring seals and 16 umbrella seals.

    So I can put all oring seals on the one set of heads that I'm using, like oem came with, or I can make use of the umbrella seals if they have some advantage on the exhaust valve...?
    ...what's your advice?


    As a followup, is there any difference between the valve stems of gt40 heads and e7te heads, I don't need to order a 3rd set for the gt40 heads do I?

    Both sets are made in the US, one from sealed power and one from victor, so neither should be crap: but one set says "viton" and is just black rubber, the other, as far as the oring half for the intake, has this white plastic insert in the middle, which was weird.
    What's that plastic insert, and which set do you think is better if I have to pick one for my car?

    Hopefully assembling tomorrow night-- let me know!
    Last edited by BerniniCaCO3; 03-15-2011 at 12:51 AM.

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    I put 16 umbrella seals on my car and was told that was cool. The o-ring ones had been beaten to death and shattered, see my thread in the lounge. It was evident that my measley cam somehow had enough lift to kiss the seals, and since the umbrellas are shorter I went with those.
    1992 CVLX. 5.0 HO/GT40P/T5/3.73/trak-lok with bolt ons. 02 front CVPI setup, rear HPP setup, CVPI shocks around, F250 radiator, e-fans, and the power of 3G. 15.92@89mph, 2.4 60', 4700' elevation (5500' DA) with 3.08 open rear and the old oil chugging 289.

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    I haven't seen anything other than Positive type valve seals on GT40P, GT40, E7, E6. They are the best. O ring seals suck. Umbrella seals are better, but the Positive valve seals are stationary, and squeegee the valve stem to keep the oil from getting sucked into the combustion chamber.
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    Original Positive type
    Replacement Positive type

    O rings are just O rings. They fit on the tip of the valves like chevys and older ford heads.
    Umbrellas are like the positive type, but instead of being stationary, they move up and down with the valve itself.
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    Oh-- yeah, the oem was positive type all around, then. I was just confused about what they were called.
    I don't think I've ever seen an o-ring type valve seal then.

    I did notice, I can't remember which pair of heads, that there were little plastic washers that were above the seal itself, riding on the stem like an umbrella seal does. Might as well reinstall?
    Actually, were those o-ring seals, just on top of the positive type?

    Now, the positive type with the white plastic inserts: could the insert be teflon? If so, maybe put the white plastic ones on the exhaust side which is hotter?

    Final question: all the chimneys (I believe that's the correct term), are rough cast metal and don't seem especially precision even by roughcast standards. Furthermore, in installing valve guide sleeves, I accidentally dinged up one of the chimneys when the airhammer slipped. Inside is clean and reamed, outside of the top of the chimney has a burr where the soft iron was mashed. Should I worry about deforming the positive type seal, or should the flexible rubber outer skirt of the seal accommodate such irregularities just fine?
    If it really could be a problem, I'll try to carefully file it if I can.

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    Quote Originally Posted by BerniniCaCO3 View Post
    Oh-- yeah, the oem was positive type all around, then. I was just confused about what they were called.
    I don't think I've ever seen an o-ring type valve seal then.

    I did notice, I can't remember which pair of heads, that there were little plastic washers that were above the seal itself, riding on the stem like an umbrella seal does. Might as well reinstall?
    Actually, were those o-ring seals, just on top of the positive type?

    Now, the positive type with the white plastic inserts: could the insert be teflon? If so, maybe put the white plastic ones on the exhaust side which is hotter?

    Final question: all the chimneys (I believe that's the correct term), are rough cast metal and don't seem especially precision even by roughcast standards. Furthermore, in installing valve guide sleeves, I accidentally dinged up one of the chimneys when the airhammer slipped. Inside is clean and reamed, outside of the top of the chimney has a burr where the soft iron was mashed. Should I worry about deforming the positive type seal, or should the flexible rubber outer skirt of the seal accommodate such irregularities just fine?
    If it really could be a problem, I'll try to carefully file it if I can.
    get rid of the burr. don't want to cut the seal. idk what plastic washer you're talking about.
    Got any pics?
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    here we go:
    pretty much exactly this seal, same brand too:
    http://www.google.com/imgres?imgurl=...1t:429,r:2,s:0

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    let's do that more elegantly than a link:

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    I'm not sure. If it doesn't say otherwise I would say that the plastic thing stays in there. But don't quote me on that. Or maybe it's there to assist in the installation of the seals.

    Also, before you put your valves in, make sure any burrs are removed, otherwise they'll tear up your valve seals, and damage your valve guides.
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    Quote Originally Posted by 86VickyLX View Post
    I haven't seen anything other than Positive type valve seals ....They are the best. O ring seals suck. Umbrella seals are better, but the Positive valve seals are stationary, and squeegee the valve stem to keep the oil from getting sucked into the combustion chamber.
    That's my ranking as well. Some machine shops have little condom looking things you can slip over the end of your valve and then install the seals. Even if you debur the ends they can get messed up going over the lock grooves.

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    See those positive type are what I was expecting to be handed at the parts store counter but for me my choices were umbrellas or the kind I had that would just get smashed again. Wasn't too sure what would work on my old 289 heads.
    1992 CVLX. 5.0 HO/GT40P/T5/3.73/trak-lok with bolt ons. 02 front CVPI setup, rear HPP setup, CVPI shocks around, F250 radiator, e-fans, and the power of 3G. 15.92@89mph, 2.4 60', 4700' elevation (5500' DA) with 3.08 open rear and the old oil chugging 289.

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    Alright, due to misinformation/bad tools/incompetence I screwed up my valve seats yesterday in class and had to visit the machine shop today. Add $180 to the already-bloated budget *sigh*
    While there, I went ahead and asked a couple questions I hadn't gotten good answers to, this valve seal question being one of them.

    The machinist confirmed that the white insert is in all probability teflon, but, that teflon also has a history of not allowing as much oil past as the more flexible and just as heat-tolerant viton.
    Well, it's a balancing act, as you obviously don't want too much oil let past! But that teflon can starve the valve stems of oil.
    Now, as far as the umbrella on the exhaust, which confused everyone, the reason there is that umbrella seals can let past more oil, they aren't as good a seal as the positive type; but because they run hotter, and burn off the oil faster, exhaust valves can need more oil so you put on an umbrella seal.

    From the switch, what I might see is slightly more burning oil (although should be more than made up for by not leaking oil from every 20yr old cork and rubber gasket), but, exhaust valves should wear longer.

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    hey crownvicman, measure the cast iron stem that sticks up and tell me the diameter? It might be that 302 seals will work for you, in which case just tell the counter guy that you now own a '96 explorer or a '90 crown vic or whatever, and then he'll find positive type seals for you The '96 explorer did come up with positive type all around (intake and exhaust) if you want them; the mustang and colony park (different heads, but must be the same seals) came up with the positive/umbrella mix on rockauto and on northernautoparts.

    The seals I've got sit less than 1/4" over the iron stem, so the springs would have to be very compressed to mash them; what kind of seal did you have, that it was sitting so high as to be hit by the keepers/retainers?
    Last edited by BerniniCaCO3; 03-16-2011 at 11:24 PM.

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    Quote Originally Posted by PushnFords View Post
    That's my ranking as well. Some machine shops have little condom looking things you can slip over the end of your valve and then install the seals. Even if you debur the ends they can get messed up going over the lock grooves.
    The felpro ones came with the plastic installers.
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    Quote Originally Posted by BerniniCaCO3 View Post
    From the switch, what I might see is slightly more burning oil (although should be more than made up for by not leaking oil from every 20yr old cork and rubber gasket), but, exhaust valves should wear longer.
    I would not purposely want an oil burner. How long did those heads last from the day they were put on to the day you pulled them off?
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    Quote Originally Posted by BerniniCaCO3 View Post
    hey crownvicman, measure the cast iron stem that sticks up and tell me the diameter? It might be that 302 seals will work for you, in which case just tell the counter guy that you now own a '96 explorer or a '90 crown vic or whatever, and then he'll find positive type seals for you The '96 explorer did come up with positive type all around (intake and exhaust) if you want them; the mustang and colony park (different heads, but must be the same seals) came up with the positive/umbrella mix on rockauto and on northernautoparts.

    The seals I've got sit less than 1/4" over the iron stem, so the springs would have to be very compressed to mash them; what kind of seal did you have, that it was sitting so high as to be hit by the keepers/retainers?
    It's all put back together now. Once I get it running again, I'm going to monitor oil consumption and base my long term engine plan on that. I do still have that P engine on the stand to check the seals and diameters of. I won't put it in with the weak dick stock springs. Valve float at 5k on a motor that raps out to 5500?
    1992 CVLX. 5.0 HO/GT40P/T5/3.73/trak-lok with bolt ons. 02 front CVPI setup, rear HPP setup, CVPI shocks around, F250 radiator, e-fans, and the power of 3G. 15.92@89mph, 2.4 60', 4700' elevation (5500' DA) with 3.08 open rear and the old oil chugging 289.

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