On aluminium?
Yes sir on aluminum. brings back memories of my youth when we would fill balloons with hydrogen
This LD2 engine was a dunker and was probably removed from a lifeboat that spent sometime submerged , the underside of the cylinders has just as much rust as the topside. After applying a bit of heat the sodium hydroxide has done its job I've now turned the engine block upside down filling the cylinders.
I'm not trying to save the pistons, usually when their stuck this bad I drill them full of holes from the top then bust them into the oil pan.
I see that the counterweights are bolted onto the crankshaft, I have my suspicions the same crank was used on some of the larger engines and that they ( Lister ) just used larger weights affixed to the crank.