With my 51, it had sat for around 17 years outside. It took me a week to get it to turn. Once I got it started I could tell there were no bearing noises but there was some smoke. I wanted to work on it in place and if the bearings were knocking, that option would have been a non starter. Everything turned out well.
My 38 sat in a garage for 30 years. It turned over fine with the fan belt and had good looking oil in it. I pulled the wires off the plugs to take them out and the wires stood on their own in place! I was able to get it running and it sounded good with no knocks. It also didn't smoke. I will however take it out and tear it down eventually.
