I drove our '21 Touring, with it's fresh engine, having 40 hours max on it, about a mile to the local store and when I cranked it to start home it was running on three cylinders. Shorting out the plugs, one at a time revealed that # 1 was the problem. The spark however, was strong on all four. After removing the front side cover I can see that the #1 exhaust valve is not closing. At first I was prepared to remove the head and replace the valve, spring, and keeper(s). But I suppose I will try to get some lube into the plug hole to the valve stem and try to free it up. I hope the valve seat is still in place. There was no noise when the problem began and now when the engine runs on three cylinders, so maybe the seat is intact.
