Guys, I did the valve stem seals on my Sy and all was good as far as the start up smoke show. I do have an issue with a low speed miss that I am still chasing that I found last month when I drove it to Richard Clarks place for the Buick meet but that hasn't been bad enough to keep me from putting around here and there though. So now after about 400 miles total the truck has started to smoke again when cranked. I though that maybe I didn't get one of the seals on good enough and it pushed off the seat. Anyway, started pulling it apart and when I pulled the springs on number one I found that on both the intake and exhaust valve, the o-ring seal had come out of the groove and was pushed to the bottom of the stem. What could have caused this? The keeper moves with the end of the stem and it should stay in relatively the same orientation so it couldn't push the seal down and the keeper should keep the spring from contacting the seal. If there was too much valve lift then it would seem that the seal would have been pushed to the top of the stem above the groove. There is no noticeable wear or stem movement in the guides and the valves rotate easily through the range of motion so nothing is bent. I know they were in the groove when I put them on and the snap on seal was still in place. Could the O-rings be the wrong size? I used Fel-pro seals, which are usually pretty spot on. Anyone else had any problem with them? Anyway, I ordered a different brand which will be in next week and I'm going to give them a try. On the plus side of this, I have gotten pretty good at pulling the valve covers off and thank goodness I changed the hard i/c pipes out for heater hose.