I did it for a couple days with no appearent change. Is there something better to boil it in? I thought about using a propane torch but a little leary of getting it too hot. Was hoping to loosen it up and clean it up before assembly as to keep the crap from scratching the cylinder wall.
A lot of years ago we had an antique engine that the piston,cast, was stuck into the steel cylinder. We soaked it in different things for over a year and no luck. This was a big stationary engine with a bore of about 6". Used an old hydraulic cylinder ram and a 15 lb. sledge directly on the piston every month or so to no avail. Then an old wise man said to soak it in lacqer thinner. Did so for a month or so and tried the sledge again. It moved! Just enough to see it had. Some more soaking and hammering got it out. Later it did run. Same piston and rings. They just don't build like they use to. Sometimes that's a good thing.