Traditional high speed Babbit alloy has never had Lead in it. It's an alloy of Tin, Copper, and Antimony. Since the mid-1940s, precision steel backed insert bearings have been a multi-layer construction with a steel outer shell, with a layer of copper bonded to it, and a soft metal layer that can be Babbit, aluminum alloys of various compositions, and other combinations of soft metal. On top of all that, there is a microscopic layer of pure tin, to facilitate quick "wear-in" to small irregularities in the crankshaft surface. Lead alloy Babbit hasn't been used in engine bearings since the 1920's or earlier. The original equipment "soft" metal used in 216 and early 235 connecting rods is so hard that it will dull a tool steel lathe cutting bit in a hurry. When I'm boring a spray-oiler rod for insert bearings, I have to use a carbide cutting bit.
Jerry
