I own and operate a commercial machine shop specializing in heavy engines, also restore old engines as a hobby. it would be a real shame to hack lumps off the original crank, plus there is the unknown quantity of how much the crank would be affected. In this case my first reaction would be to polish the crankpin back to clean metal to determine how bad the pin actually is. Based on the photo (which admittedly is not a close up) the pin does not look too bad. In many cases, it looks worse than it is due to melted babbit adhering to the pin. When this is polished off, it will look a lot better. When the pin is cleaned you can assess the actual wear and damage to the pin. If there is only slight scoring and ovality, a lot of this can be polished and stoned out using water or oil stones. Remember that the engine will probably never be run under the original design load, and also will never run the hours it has already run. In general if you can restore up to 70% of the original bearing surface, it will work fine. I know this is not ideal, but it will be infinitely better than chopping lumps off the crank. I have hand polished similar sized crankpins in the past which have gone on to run for thousands of hours. The actual finished size after polishing is not critical as you have to make the bearing fit anyway. Try it, you have nothing to lose and everything to gain, it will cost next to nothing, and with care and constant measuring, it will work. more than happy to offer practical assistance if required. Wheelwright.
