stem seals different, what gives?

[Casperfast]

so I'm changing my valve Springs and stem seals while I'm in there. But I noticed immediately that the old seals I removed look identical to each other from intake to exhaust. But the new ones I got in the fel pro package are different. In the photo the ones in the rear are what i removed and the ones in the front are the new ones. The shorter seal appears to not slide over the pedestal like the longer one does. Should I still run them like this or get another set of the right length? I double and triple check the part numbers and they are correct

 

[c9zx]

I THINK Fel-Pro is servicing all 351C and 351M/400 with the later 351M/400 seals and the exhaust seal is shorter than the 70-74 351C seal. There may be a difference in the material, intake to exhaust, due increased temperature at the exhaust valve stem. I believe the OEM intake and exhaust seals were the same height for the 70-74 351C. Perhaps someone with the Ford parts books can confirm this for you. Chuck

 

[Casperfast]

ok, thank you. i hope someone is able to confirm this or if i can or should run these.

 

[Stanglover]

There was a recent post that included info on valve stem seals.

In my initial rebuilt engine, these Fel-Pro seals leaked oil and as I had other issues with that rebuild, the engine builder switched to a type of seal that has a spring like band in the lip around the stem. These were Pioneer OS1045, but there are other brands of the same type. The result is I now have no oil usage. I have not actually seen these seals other than a sample that the builder had on hand.

I would do some more research before installing a seal type that might fail on you.

 

[Casperfast]

well felpro is far from a company that needs to be researched. but i was able to determine that the clevelands of later years 75+ did utilize 2 different size stem seals. and that with mine (our) application we need a different set. i have found the type that uses the spring collar but those require machine work to adapt. i will just go with the standard oem replacements.

 

[Stanglover]

well felpro is far from a company that needs to be researched. but i was able to determine that the clevelands of later years 75+ did utilize 2 different size stem seals. and that with mine (our) application we need a different set. i have found the type that uses the spring collar but those require machine work to adapt. i will just go with the standard oem replacements.

Okay, I checked my receipts and found I made an error in my previous post. The seals were NOT Fel-Pro, but Sealed Power ST2001. These are the ones that caused issues on my rebuild. I'm not saying they are bad seals, but they leaked oil on my engine. The Premium Fel-Pro seals that were included in the gasket set purchased for the build were never installed and are in my junk box. These are basic style, no spring insert and all 16 are about 3/4" long if that helps.

Good luck with your choice.

Sorry if I mislead you.

 

[Don C]

Calling these, and the OEM, seals is a little misleading. They are just umbrellas that are designed to keep oil from the rocker arms from running down the valve stems. Splashed oil still gives plenty of opportunities for the stems to get wet, allowing oil to run down into the ports, especially the intake port, as the valve guides wear. The longer umbrellas help by extending down over the top of the guide, but are still not a positive seal, and allow oil to be sucked into the intake through worn guides. Worn exhaust guides blow the oil under the umbrellas and back into the valve train and engine while the engine is running.

 

[secluff]

Casperfast, the production installed and service Ford valve stem seals were the same for intake and exhaust. 70-74 H and M used the DOAZ-6571-A seals. 71-72 Q used the DOOZ-6571-A. Since there were some cylinder head changes for the 73-74 Q 351, Ford used a D3TZ-6571-A truck line sourced seal. The early 1975 351M and 71-74 400 also used the DOAZ-6571-A seals. As Chuck mentioned with emission controls causing increased exhaust temperatures Ford went to separate intake and exhaust valve stem seals in 75. The DOAZ-A and DOOZ-A seals are 7/8" OD and 11/16" high.

The "R" Boss 351 and HO used the C9ZZ style Boss 302 style seal which was a different "Animal".