Rebabbiting rods is not terribly difficult, but it does take some special tooling that's just not available in most places. I've done the machining on babbit rods to accept insert-type bearings several times, and it eliminates the problem of fitting the bearings to the crankshaft after they're re-poured.
An old service manual I've got stashed away somewhere gives directions for fitting babbit bearings, and it involves bolting the bearings up dry, no oil, and spinning the engine with an electric motor until "heavy smoke comes from all the bearings"! This smears the babbit around the crankshaft. Then the crank is polished and the high spots in the bearing are scraped until there's a perfect fit with the crtankshaft, using Prussian Blue dye as an indicator. Once a perfect fit is established, shims are added between the connecting rod and cap to establish the correct running clearance. Setting up a babbit-rod engine correctly is a dying art! On the older ones with poured main bearings, the same procedure had to be done with the mains, also. After about 10,000 miles, some shims are removed to re-establish the oil clearance. Insert-type bearings are a lot simpler to service!
Jerry
