What I'd like to know more about is the "scrapping" to fit part of the process
Scraping is the easy part- - - -just coat the bearing surface with an indicator dye like Prussian Blue, put the shaft into the bearing, clamp the cap on with just a little pressure, and rotate the shaft. When the shaft is removed, any bright area in the bluing is a tight spot. Using a tool like a 3-cornered file with the teeth ground off, gently scrape a thin layer of Babbit away where the bright spot is. Recoat, insert the shaft, "rinse and repeat" until you get a smooth smear with no high spots, indicating a 100% shaft-to-bearing fit. Then shim the cap to achieve whatever oil clearance you want. When dealing with multiple surfaces like a crankshaft in a set of main bearings, it's a good idea to work all the bearings at the same time. Otherwise, fitting one bearing can alter the fit of the next one in line. I've seen a few oldtimers fit bearings so tight that the car had to be push-started with sandbags in the trunk for traction, but that was just too tight to suit the guys around our shop back in the 1950's. Fun stuff!
Jerry
Edit: One sneaky trick is getting the Babbit metal to bond well to the steel or cast iron connecting rod, block, etc. It's similar to the way our body shop man got body fill lead to stick to sheet metal. Coat the area with acid core solder and use a coarse rag to wipe away any excess while it's still hot, leaving a thin, shiny tinned surface. The Babbit bonds to the solder, leaving a high-strength bond to keep the bearing material from spinning.
Jerry
