Farmall Cub

William and Olympia are early Cubs with Magnetos. I was trying to crank both with the hand crank till I got a battery installed ,I have not seen either Cub run. I was told that Olympia ran a year ago. Now neither one's engine will spin with the crank. Both will roll when in neutral. I find it hard to believe that both engines have locked up in such a short time. Any suggestions on where to look next.
Thanks, GAGoober.

Remove the spark plugs and shoot a little of your favorite penetrant into each cylinder. After setting for a while, crank them with the plugs out or jack one rear wheel up (carefully), put it in third gear and try rocking the raised wheel back and forth to see if it will break free.

Yes, under the right circumstances they will stick in that short a time. Without knowing their history, it's kind of a WAG, but the firtst thing I'd do is pull the plugs and see if you can turn them over then. As I mentioned in another post, you might try removing the starter and see if you can back the engine up using a large screwdriver or a small prybar. If you can, you probably have a stuck valve. If not, one or more of the pistons is probably stuck. If it's a piston, pour some penetrating oil in the cylinders and let it set a couple days before trying it again. If valves you'll probably nee to pull the head and side plate where you can get to them and soak them with penetrating oil.