Know this is an old post but thought I would share my experience because this is the closest thread I found. Recently I purchased a truck with 850 miles since overhaul 13 years ago on its 216. Obviously it was parked a lot and I think for long periods of time in between drives. A combo of old gas with ethanol and sitting resulted in four severely stuck intake valves and bent push rods. Could barely be tapped open with a brass hammer. I tried a lot of the remedies mentioned on this site and others. All the lubricants and home brewed remedies, etc. Some didn’t work at all, some worked but the valve would be stuck again when I tried it the next day. What finally worked was acetone. Putting it in a small squirt bottle, and squirting it on the valve stem and working the valve. Then I put the valve stem in a cordless drill chuck and SLOWLY turned the valve while gently working it opened and closed. The valve would be stuck, stuck, stuck, and then all of a sudden free and working flawlessly. I know someone will probably think that was a bad idea but it was a last ditch effort before having to pull the head, and it worked. Engine is back in business and hums like a sewing machine. After you get the valves working, change the engine oil before starting! Will also have to put new valve stem seals. And lubricate anything that won’t be oiled immediately, including the valves and the assembly. Good luck!
