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| full umbrella vs semi-umbrella valve seals https://slantsix.org/forum/viewtopic.php?t=27280 |
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| Author: | 1969ronnie [ Tue Feb 19, 2008 7:53 am ] |
| Post subject: | full umbrella vs semi-umbrella valve seals |
hi,i'm measuring my valve seal to retainer clearance. i have shortened my valve guides and the problem i see is that i can shorten the guide down to where i need it for full valve lift clearance plus .050(.500 seal to retainer clearance to allow for future 1.6 rockers or bigger cam swap), but the full umbrella seal will touch the head with clearance between the guide and the seal. no one seems to use the semi-umbrella seals. is that what you have to use with the high lift cams in this situation?i don't want the positive valve seals if i can avoid it. the other problem is the valve seals are almost 3/16 thick . any co.s make seals that aren't as thick? ron |
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| Author: | Joshie225 [ Tue Feb 19, 2008 9:19 am ] |
| Post subject: | |
Plenty of Chrysler V8s used a shorter umbrella on the exhaust valves. I know I have a package of 8 short FelPro umbrella seals at home. Try FelPro SS12764. |
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| Author: | Doc [ Tue Feb 19, 2008 9:23 am ] |
| Post subject: | |
Using a sharp pair of scissors on the long stem seals has always worked for me. DD |
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| Author: | BigBlockBanjo [ Tue Feb 19, 2008 10:58 am ] |
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Why are you avoiding the positive seals? Is it the machining, or...? Price? |
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| Author: | 1969ronnie [ Wed Feb 20, 2008 11:05 pm ] |
| Post subject: | |
hi, its not the price or the machining for me . the pc ones are not needed in my application or recommended unless you are running more than .510 or .520 valve lift or using dual springs. using the "search" on here doc and others post about them. they say the guides don't get any or barely enough oil on quite a few posts under valve seals and will wear the guides prematurely. my original question about the stock umbrella seal is that its tall and over .1875 thick and the 3 raised ribs/pads under the seal make it sit .200 off the guide. i shortened the guides years ago from stock .6875 to .5625 to run my old 244/.436 cam. i was looking for a seal that was "thinner" and shorter so i could keep the guides as long as possible without further shortening. i will measure the ss12764 and ss13955 and see whats better or use another application that will fit and work. i just don't see why a valve seal needs to be .200 thick to deflect oil. thanks, ron |
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| Author: | 1969ronnie [ Thu Feb 21, 2008 10:34 am ] |
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hi,since i have .660 retainer to guide clearance with no seal and .460 with a seal ,im going thru my felpro and victor reinz master catalogs . both have over 1200 pages of info so it takes time. i have found 12 pages of valve stem seal specifications and charts and am going thru the data. no need to shorten the valve guides more for my new cam just because the seal is too thick. the "shedder" type seal that slants use have tons of different specs including inside depth measurment and thickness. i have already found part numbers that will work and fit better . i will post my findings . anyone ever try to run a slant with no seals as a test and have a response of results? race only?big oil burner? it looks like some racers tighten up the guide clearance and remove the seals. i would never do it, im just reading some more valve seal posts. ron |
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| Author: | AnotherSix [ Thu Feb 21, 2008 12:57 pm ] |
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I didn't notice what type of guides you are using, Bronze? I have run turbo Buick engines without exhaust seals and they do burn some oil, not too bad. They came that way from the factory. I would never try to run without intake seals. It will put a huge amount of crud on the valve and burn quite a bit of oil while fouling the chambers and pinging more. I would try trimming the normal umbrellas as already pointed out, or find the longest ones you can that will fit. The short OEM style seals are really for the exhaust side. I do not believe they will be enough on the intake side. The issue I have with positive seals for a long mileage street engine is that they do not work well after the guide has worn some. New ones will go bad right away if they are installed on a loose guide. The umbrellas do not survive that well on a real high rpm engine, but are simple and very effective for most street engines. They are what I will likely be using on the head I am about to get together. Cheap and easy! |
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