I've searched the posts and found some good stuff on valve seals. Looks like I have the classic symptom - big puff of smoke at start up. It's on one side and probably just one cylinder since plug #1 seems to be the one that's fouled.

I'd like to try replacing the seals without removing the heads like I see mentioned in some of the posts but I didn't find any instructions on how to keep the valve from falling into the cylinder...

Any ideas would be appreciated!...