Anytime an engine stops, at least a few cylinders will have the valves open. That allows humidity to attack the cylinder walls and rings, and it won't take long to seize up the rusty cylinders. Pour several ounces of a 50/50 acetone/automatic transmission fluid mixture into each of the spark plug holes. Replace the plugs and let the engine sit for several days. Then use the chisel end of a long shepherd's crook wrecking bar on the flywheel teeth at the edge of the bellhousing to nudge the crankshaft back and forth. Last resort- - - -pull the cylinder head and use a block of hardwood and a big hammer to get the pistons moving. Most likely, the cylinders will have to be rebored if you decide to try to salvage the block. If it's cracked, why bother?
The next time you put an engine into long term storage, remove the intake and exhaust manifolds, bolt a piece of plywood over the ports, and put several ounces of heavy oil into the cylinders.
Jerry
