Went to install some new valve springs and found this dual spring setup on there and it appears that the valve guides were machined for a slightly smaller diameter valve seal for the inner spring to fit because the regualr viton LT1 seal will not fit in the spring and is too loose on the head.
I'm going with a beehive spring not the dual ones so I just need a valve stem seal that will work...
This must have been a common practice before beehives so I'm hoping someone knows what this smaller diameter seal is so I can pick some up at the local auto store.
The valve stem itself is the same size as stock..just the part of the head it fits down on has been machined just slightly smaller.

Here's a pic of the spring and the inner spring...the new LT1 valve seal is on the left..the old smaller one is on the right.

 

Measure the OD of the guide, but the normal size for smaller seals is .530", at least that is what mine were machined to. The picure looks a lot smaller though.

 

Ok, my digital calipers readout is hosed, but using the scale on the side the stockers measured to be .550"...if that is correct, then these measured to be .510"

Will an auto store be able to look them up based on that diameter??

 

well, correction, I poped in a new battery and the digital calipers seems to work, but the stockers measured in at .557" and these were .527" so the seals you used for your .530" would probably work, do you recall a part# or what vehicle they came on to get them at the local store?

 

I found Comp part# 503 for teflon seals and #529 for viton seals for .530" bosses and 11/32 valve stem diameter.
These what everyone uses?

 

I got mine from Ai with the heads. As long as they are seals for .530" guides and 11/32 valves you will be fine.