The post I made last night didn't show up for some reason. Absolutely DO NOT try to shim the rod for a better fit. That is only done on Babbit bearing engines, and no 261 was ever made with Babbit rods. Remove the cap and bearing shells from the tight rod and inspect the crankshaft and bearings for debris, scoring, or other causes of the sudden lockup. I'm going to guess a piece of debris left over from an oil passage has found its way to the rod journal and jammed the works. Measure the diameter of the rod journal with a micrometer, NOT a dial or digital caliper. A properly ground .020" undersize journal should measure 2.2925" +/- less than .001". There should be no scratches or score marks on the crankshaft and no debris imbedded in the bearing shells. I have an idea that the engine builder might have been a little careless about assembling the engine in a clean environment or he did not clean the oil passages properly. Oil clearances are less than the thickness of a strand of hair, and a dirty buildup has wrecked untold numbers of engines. Good luck!
Jerry
