Valve Stem Seals, Which ones?

[Mxlt]

I bought a Felpro Gasket Set for a 360 and it came with a couple bags of Valve Stem Seals. Question here is which set is better. One bag has some clear ones and are Nylon. The other bag has black ones and are Polycrylate. Can anyone provide some recommendation. Here some pictures:

[Mxlt]

Anyone? I really need your help here. I'm working on tthe 360 heads and need to complete this part.
Thanks

[Retro93]

Either will work fine as long as they fit tightly around the valve stem/head boss. Personally, I use polyacrylate...no good reason...just always use them.

[Ristow]

try the black ones,the nylon ones seem to walk up,off the guide.

[Mxlt]

Muchas Gracias Amigos. I knew I could count on you. You are a big help. Now I'll keep working so I can finish up this step.

Regards

[Arborigine]

Just out of curiousity, what does the printing on the bags say?
I am going to replace the valve seals on my engine while it's out.

[Driftwood]

I am beginning the teardown to replace my valve stem seals. So between the two types of seals, which ones were used?

[JeepsAndGuns]

Back from the dead!!...lol

I just had a set of heads re-done and got the same two bags of seals in the gasket kit. I took them both to the machiene shop and asked them. He said the nylon ones are better. So I took his advice and used them.

[Serious Johnson]

Back from the dead!!...lol

I just had a set of heads re-done and got the same two bags of seals in the gasket kit. I took them both to the machiene shop and asked them. He said the nylon ones are better. So I took his advice and used them.

Ha! I did the same thing, and they used the black ones. So I guess the official verdict so far is "who the heck knows"?

S.J.

[Ristow]

....and i've since decided i like the nylon umbrella seals better,lol!

[Lindel]

Remove all doubt, use both!

[JeepsAndGuns]

Ha! I did the same thing, and they used the black ones. So I guess the official verdict so far is "who the heck knows"?

S.J.

Probably no one!
I wonder just how much of a diffrence there really is. I think either one will work fine. But I am keeping the extra ones, so incase these start leaking, I have some new ones...lol

[Walt]

They spec the rubber one for older cars and the nylon for newer. I asked my machine shop guy which ones I should use and he said "Aw hell, it don't matter. I always just use the black ones".
That guy turned out to be an idiot. After the 2nd time he botched the heads I took them to a competent shop and had them machined for positive seals while they were machining for rocker studs.
No offense to anyone who recommended the rubber ones...
Seriously, though, I think the only reason they put both in the package is because the older motors originally came with rubber and then at some point they improved the design and switched to nylon.
I found a bunch of rubber chunks down in the oil pan from deteriorated rubber seals, so I imagine they felt nylon was an improvement. The nylon ones fit tight on the stem but may eventually will crack and get loose on the stem; the rubber ones go on real easy, but will get hard and then eventually start breaking up as they continue to deteriorate.

[Lindel]

In all seriousness, Walt is right. If you're in a hurry, use the rubber ones (not really rubber, but close enough). If you've got time to spare, use the nylon ones.

Quick note to make them a LOT easier to install, heat them in boiling water, they'll slip on with no fuss.

[RWalker]

When I pulled my engine apart it had the nylon seals and they were cracked up so I went with the black ones. It didn't smoke with the cracked seals and doesn't smoke with the new black ones. Either way you'll have a back up set and if you did them yourself you'll know how to install them if needed.