Valve stem seal debate...

[mungus]

So now I'm shopping for valve stem seals...

I've already ordered a full "premium" Felpro gasket set from Summit (whatever that is), that includes the black umbrella seals, but I see some of us opt for VITON or PFTE type seals. The COMP cams seals I was originally going to order require guide OD machining to fit... 

I'm used VITON seals on other engine builds so no dramas there and in my limited experience they seem better constructed than the rubbery / nylon umbrella types. How about on the FE's? I'll probably be running bronze inserts I'd imagine, so I assume they won't need lots of oil leaking down there to keep them moving OK.

So my questions are;

Are the umbrella type standard seals that bad on FE's? Do they break down quickly?
Is it really worth getting machining done just to go to VITON stem seals?

I see "Alex's Parts" sells VITON seals that should fit my OEM guides OD (.652") without machining, but I have my doubts they will clear the COMP cams inner valve springs I'm using. Their ID is .697" so it would be damn close IMHO... (ie I'd say touching). Alex sells a bunch of sizes in VITON seals so I guess I need to know how big a seal I should fit...

I'm guessing machining the top of the guides is the only way to get both VITON and good springs...
Can anyone recommend what size to buy to clear my dual spring inners at .697"?
I see Barry is offering the .562" VITON's. So perhaps they are the go for my set up?

All views appreciated as always.

[Barry_R]

If you want to run double springs you have to machine the OD of the guides. 

The large .652 seals (I do have them - originally a Mack Truck catalog application ) will physically clear but the springs will grab them when running.  The .652 seals work great on single springs.

[Falcon67]

I like the Viton units, I keep .500 and .531 parts on the shelf.  Except for the GT40 heads on the 302, those use two different seals (intake vs exhaust) so I get the Ford part numbers.  And yes, all guides get machined for these parts.  I have some Comp parts, didn't really care for them.  The Engine Tech parts have given good service.

http://enginetech.com/products/product-categories/valve-stem-seals/

[mungus]

If you want to run double springs you have to machine the OD of the guides. 

The large .652 seals (I do have them - originally a Mack Truck catalog application ) will physically clear but the springs will grab them when running.  The .652 seals work great on single springs.

Thanks Barry, I presume your .562 Vitons will work? Or would you recommend using something bigger to preserve guide thickness? Or perhaps do you fit a different complete guide that's the appropriate OD. Interested in your recommendations.

[cjshaker]

I'd definitely stay away from the umbrellas. Poor sealing compared to the others, especially if you have any oil pooling in the heads, not to mention the issue of breaking up over time. As to what type is best, I'd listen to the pro engine builders here.

[afret]

If I remember right, I'm using the .562 viton seals on Edelbrock heads with Comp 955 double springs. 

[mungus]

Thanks Afret. I know the Edels are a whole lot better in lots of ways, bronze guides etc.
However I'm going for a stock look while trying to improve things a bit, so they are out for me. Nevertheless it's good to know the .562's clear your doubles OK. That size only removes .09 of an inch from my OEM cast guides, so only .045 wall thickness. I think they'll do me...

Barry sells em, so it's Survival to the rescue again... :-)

[mungus]

I'd definitely stay away from the umbrellas. Poor sealing compared to the others, especially if you have any oil pooling in the heads, not to mention the issue of breaking up over time. As to what type is best, I'd listen to the pro engine builders here.

That's what I guessed. VITONs it is...

[manofmerc]

I found this on the other fe forum a couple of years ago .Pioneer has a umbrella seal #os104.It has a ring that tightens the seal to the valve stem and another that will hold it to the valve guide .I have these on my stock cj heads with no issues for the past four years .You don't need to do any machining for them to work .My valve springs are singles with a damper .Dual springs might be a different story so keep that in consideration.I bought them from jegs and they are cheap!(less than $10.00) the jegs website has a good pic.For stock iron heads these are a great seal for a mild streeter with single springs .Carry on! Doug

[mungus]

Thanks Doug.
However I will be running double valve springs so I need a fairly slim seal OD.

[manofmerc]

You know I gave out the wrong # It is OS 940.Pioneer where I came up with that 104 number is beyond me.Good luck with your seal install which ever one you use .Just stay away from those crappy white Teflon seals seems to me they don't hold up very well .

[My427stang]

Agree stay away from Teflon, seals at the beginning, but has no significant ability for valve movement and limited grip on the valve once any wear sets in

Here is a good page to see what is out there.  I buy from them in the top three sizes, going from memory, at work right now, but I believe .562, .531, and .500 I keep on the shelf

http://usseal-eok.com/seals-by-size.html

[mungus]

Thanks. Yes I'm going for VITON, just the sizing I need to sort out.
I'm fitting COMP double springs, so I need to check out some specs and see whats the biggest seal that will fit without catching.
I'd rather not have to machine off any more cast iron than I need to.