When I was working in a local machine shop, we converted a lot of babbited rods to insert-type bearings with a special bearing set from Federal-Mogul. The babbit is melted out with a torch, at fairly low heat, the big end of the rod is bored to the correct size, and the bearing fits into the rod like the later models. No more shimming, fitting, or any of the other headaches associated with poured bearings! It's got grooves for the splash lubrication, and uses all the original dippers, etc., just like the babbit rods.
Jerry
