Ok, I have a set of dual valve springs that came off another set of heads I have, the valve stems were NOT machined, so they are the stock size, .560" I beleive.
I don't have the seals that came off of them....

So the questions is, generally, what valve stem seals are used with dual springs on stems that are the stock size??
I'm not certain what part# the springs are, but were used previously with these heads I have.

I think the metal covered vitons were what were on there, just want to make sure, the larger blue rubber ones (not sure brand) do not appear to be slim enough to fit inside the inner spring without touching it.
I had removed these springs and the seals back 1-2 years ago and are going to reuse them now just to see if the valve train stays noisey...

 

Even a metal clad viton seal may be too big with your double springs depending upon the inner spring size. The blue seal with the band is wrong for this application anyways so don't try that, you should be able to get the factory metal clads at the dealership - it's an odd size at .555 which I don't stock because I just cut the guides for a standard .530 seal.

 

Yeah, my trucks heads had been machined for the .530 seals with the dual springs, but the heads I have for the TA originally came with non-machined stems with these dual springs that I'm about to put back on.

So, are the factory seals the "slimmest" (smallest OD diameter) for the factory non-machned stems?

 

There are seals that fit .560 LT1 guides for use with dual coils. Patriot uses them with their dual gold springs. There is like .010" clearance which is super tight but they do appear to do the job with out being pulled off. Dont remeber the exact size.

Might call Patriot and order the seals from them.

FWIW. When my heads were being worked last, I had the guides machined down to .050" so the options are more wide open.

 

I have a brand new set of the fel pro viton seals for stock lt1 heads lying around but I am not sure if they will work with the dual springs you are using. They clear the crane 10308 kit but not sure on other brands.

 

Went to a few dealerships on my break, but none had the GM factory seals in stock to measure.

The Vitons are 0.680" in diameter.
The inner spring ID is 0.700" so the viton would clear with 0.010 on each side as Ben stated the patriots would clear.
May drive across town later today to a dealer that has them in stock, but they are pricey, $5 each for intake and $2.5 for exhaust.

 

Called Patriot, they use the regular metal jacketed viton seals for non-machined stems on their dual spring packages, and they have the same specs as I measured above .700" ID on the spring and .680" on the OD of the valve seal. Of course the spring ID measurement is at rest, when compressed it will become a bit larger so I should be fine.