Remove most of oil that you can from bores and try a mix of 90% acetone and 10% ATF. Remove oil drain plug & drain oil if not already done. Leave a catch pan under to see if any gets by. Let sit for a week with sparkplugs in , and check/top-up daily.
Pull the head, a hardwood block on to the piston, driven by a BFH will exert infinitely more force on the piston than what you can put twisting on a crankshaft nut.
May not be the cylinders. Try pulling them off. You can use the base nuts to jack them up. If the crank turns in the process then you know it's the cylinders. Once jacked up, an oak dowel and big hammer on top of the pistons will get them out,
Did you shout over the fence "hey, big hefty fat man, come and help", or did you have a more diplomatic approach?
Him and the Landlord were doing cement work on a wall . He was happy to help . Plugs were out . First attempt by him freed it up with simple instructions provided by the underweight 142 lb . moi . Motor oil was poured into each cylinder 2 hrs. beforehand and they were watching me install the battery before my failed attempt and subsequent request for help . He must have weighed about 240 lbs . I said thank you very much . Turned on the ign. and kicked it to life after 2 yrs. of outdoor storage , covered . Smoke cleared up after a minute or 2 .
If the engine is still in the frame as it seems to be from the picture, you might try using a cargo strap/ ratcheting strap by wrapping it around the cylinder base and getting some upward tension on it. Obviously, the nuts need to be removed or loosened. Then with the tension on it from the strap, take a piece of wood and a fairly large sledgehammer. Use the wood as a punch (saw or shave or sand it down so that it fits in close up under the lower most fin. Give it a couple of hits on one side then the other. I was able to break free a stuck-rusted-frozen, cylinder/barrel assembly on an old MKIII this way without breaking any of the cast iron cooling fins. Cj p.s. - yours might prove to be too stubborn for this method, however a combination of some of these suggestions might work if applied in unison. Cutting or drilling the piston crowns out/ off would be preferable to breaking fins or stripping studs. p.s p.s. I also had an old set of 750 cylinder barrels that I bought from a junk yard that had obviously been sitting outside for ever, and had one stuck piston in it. I put it on a hydraulic arbor press that we had in the back of the hangar (it was really stuck like chuck). I don't know the rating of the press, but I really put some umph on it and when it finally let go there was a huge spark from (I guess the ring that was adhered to the cylinder wall). But I'm not joking, it was in there brother. All that being said , remember its only metal and it will bend to your will
))
....so true.
www.evapo-rust.com
Don't use the base nuts to jack the cylinder up, if you do, you stand a very good chance of breaking a fin.. If the head is still attached and you want to lift the cylinder, try using a hammer and a piece of wood, with the wood nearly vertical and its end bearing onto the roof of the exhaust port thread. (this is the way to free a stuck cylinder head)
Of course be careful, but the nuts are not at the outside of the fins. They work quit well for breaking the seal. The point was to see of if the cylinder will lift a little so it is known if the crank, big ends, little ends, or cylinder/piston are the problem.
Rock in high gear, not first, as the mechanical advantage will be in your favor. From experience. Think how you would park your car on a hill in 1st or reverse rather than high. In high it would roll away.
