Valve Stem Seals
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Freshman User
Joined: Nov 2006
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Valve Stem Seals
I'm replacing my valve stem seals, and ran into a bit of a problem. The FelPro seals that I picked up from AutoZone are different sizes for the intake and exhaust, but the factory seals that are on my truck are all the same size. Looking at various sites (AutoZone, Kragen, Napa, etc...), it appears that FelPro has different part numbers for intake and exhaust, while most other manufacturers have the same part number for both. My instict tells me to use the same size that's on the truck, but I can't help but wonder why FelPro makes two different sizes. ... I'm planning to finish this job in about an hour, and any input would be appreciated.
Thanks!
..... 1977 Ford F250, 351M (CA emissions), 4x4, C6 .....
Thanks!
..... 1977 Ford F250, 351M (CA emissions), 4x4, C6 .....
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Freshman User
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So I've done some more research, and believe I've found an answer ...
This appears to be an error in FelPro's product line. FelPro has two different part numbers for valve stem seals, one for intake seals and another for exhaust seals. Not only are the part numbers different, but the seals are in fact different also (as would be expected by the different numbers). However, the valve stem seal "kit" that FelPro sells for the 351M contains 16 identical valve stem seals. The seals contained in the kit are the same as those found under the product number for the intake set. The seals contained within the exhaust set are roughly half the height of those found in the intake set or the full "kit", and are not the correct part for the 351M engine. So, if you're planning to replace your valve stem seals with some from FelPro, then be sure to either purchase a full 16 seal kit or two boxes of intake seals.
Take care, God bless, and have a very Merry Christmas.
This appears to be an error in FelPro's product line. FelPro has two different part numbers for valve stem seals, one for intake seals and another for exhaust seals. Not only are the part numbers different, but the seals are in fact different also (as would be expected by the different numbers). However, the valve stem seal "kit" that FelPro sells for the 351M contains 16 identical valve stem seals. The seals contained in the kit are the same as those found under the product number for the intake set. The seals contained within the exhaust set are roughly half the height of those found in the intake set or the full "kit", and are not the correct part for the 351M engine. So, if you're planning to replace your valve stem seals with some from FelPro, then be sure to either purchase a full 16 seal kit or two boxes of intake seals.
Take care, God bless, and have a very Merry Christmas.
Elder User
Joined: May 2006
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Originally Posted by DilutedImage
Sorry, you lost me on that one ... Your truck did or didn't have different sized seals for the intake and exhaust?
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Freshman User
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Okay, that makes sense now .. It confused me because my kit only had 16 tall seals, and zero short ones. Now I'm really curious about those short ones; I assumed it was a mistake, but not if your kit had them. My truck didn't have short seals on it either though, so I don't think they're important. I am curious as to what engines they're for though.
Elder User
Joined: May 2006
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no idea i got my kit from advance auto and it said on the parts list 16 valve stems and near the end it said 8 valve seals. confused the hell outta me but my buddy (a mechanic) said they were for the intake valves but you odnt have to use em. just wondering if he was correct.
he has built a nice 400 and waiting to run his 460 in the 76 shortbed f100/f150 cant remember which it is.
he has built a nice 400 and waiting to run his 460 in the 76 shortbed f100/f150 cant remember which it is.
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Posting Legend
Joined: Sep 2001
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For optimum sealing machine the intake valve guides for Teflon seals in a metal sleeve. Use the long rubber umbrella seals on the exhaust valves.
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Elder User
Joined: Feb 2002
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From: East Bend, Carolina, U.S
In my 351C I had the machine shop install graphite valve stem seals. So far after close to eight years I've had zero problems.
Also, if you run the engine at higher rpms the teflon seals are prone to separation.
Also, if you run the engine at higher rpms the teflon seals are prone to separation.
Elder User
Joined: Feb 2002
Posts: 987
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From: East Bend, Carolina, U.S
It isn't possible to accurately compare experiences in the durability of a part used in totally different engines and operating conditions. If you haven't had problems with them it could be because you didn't run the engine at high rpms long or differences in engine specs like valve lift, clearances, etc...
Seeing high rpm engines disassembled that have broken teflon valve stem seals is an attention getter. If the material or design has changed then maybe they will last better now than they did years ago.
Lastly, I have never heard of anyone complaining about the same or similar problems with the graphite valve stem seals in any engine or any operating condition.
Seeing high rpm engines disassembled that have broken teflon valve stem seals is an attention getter. If the material or design has changed then maybe they will last better now than they did years ago.
Lastly, I have never heard of anyone complaining about the same or similar problems with the graphite valve stem seals in any engine or any operating condition.
Posting Legend
Joined: Sep 2001
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The Teflon seals I used were "first generation" parts, back in 1970. I would say that was years ago... The 390 was a high performance engine running ~500HP that ran 7-9K RPMs for hours on end. Gas was cheap back then. The Teflon seals worked well and I would use them again.
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