Had a 38 Plymouth once that had a locked up engine. Tried many things, including pull starting it. Nothing worked. Dropped the pan, pulled the head and popped the pistons out. Found one cylinder that had rusted thru the cylinder wall and stopped the piston. Other than that the walls looked beautiful.

Good thing I planned a 360 swap anyway.

Yeah... If it is taking this much force to try and free it. this thing needs to be pulled.... If I did manage to get it freed up i would probably bust a ring or two in the process. I will pull the heads in a few months and see what I got...... TBF

How's it go? A boat is a hole in the water where ya throw money, and a pool is a hole in the ground where ya throw money. Ain't it the truth? Actually, I have seen 1 or 2 engines over the years that recovered from cylinders being heavily rusted to the point of being frozen, after a real soaking of penetrating type solvent. Most don't run well after freeing them up though, stuck-broken rings, pitted cyls etc..