I found a bent push rod on #1 intake of my 216. After doing a search here the problem was old gas that allowed the engine to start and run but varnish seized the valve after sitting up for a week. I did the 50/50 acetone and Marvel Mystery Oil on the valve and lightly tapped the valve to break it loose. It was still SLOW to return to the top when I turned the engine over by hand so I put a halogen work light on the valve to warm it up. That did the trick. After a new push rod & a few more revolutions to assure it was returning to position I got the engine started with fresh gas and now back on the road again. Hope this helps someone else.