I'm going to be pulling the motor in my '68 to replace gaskets, inspect and clean up. I need some advice.

The car was bought turn key with a 468 roller motor and the previous owner told me he didn't run any valve seals. Well, after it sits a while I get some smoke. I'm not a betting man, but I'm going to guess the lack of valve seals has something to do with this :D

I also found out the evacuation system's check valves were shot...that explains the condensation in the valve covers. Probably doesn't help the oil leaks either.

Anyway, I need to know what valve seals to go with. I prefer not to have to take the heads to a machine shop...but I'll do whatever it takes. The car is running a .700" lift roller cam, double springs with the iron square ports. Here's what the previous owner told me about the top end:

"valve Guides: These were either new guides or liners. You should simply check them if they are still tight. I would check valve stems for wear too, but I doubt that there is any. Beware! These are small diameter stem, oversized, and IIRC, 0.100" longer than stock."

Pull the heads-you can have them checked out and new seals installed. Saves a lot of problems in the future.

Well, the heads are coming off anyway when I change out the springs.

I guess what I need to know if a seal exists that will work with double springs.

From the previous owners statement, it sounds like he's saying the valves themselves are oversized but the stem diameter is thinner. So from that I'm guessing I can't use an off the shelf valve stem seal.

cb,
There are too many variables to answer this question without seeing the heads. If the guides have been machined for seals, then you should be able to find one to fit in the double spring. But ... it depends on what diameter the guide was machined to. There are three common ones .562" .530" and .500" If the guides were not machined for seals, which I doubt if the heads have double springs on them, then you will have to get them machined.
As far as the type of seal, I have been using the Pioneer "plastic" performance seals. Similar to teflon PC seals but a different material. Ask 5 different engine builders and you will get 5 different opinions. In all reality they probably all work ok. If all you are getting is a puff of smoke on startup ... there are a lot of guys with rat's that do not run seals. It does not seem to hurt anything at all.

have been using the Pioneer teflon PC seal with steel body.I bought 2000 in the 80s they let a small amount of oil into the guide unlike some other seals that dry up the valve guide and cause guide and valvestem wear
Curt