Hy birchbark, I think some of this info could be found by using the Search or Tech Tips features. The Chevrolet six cylinder engines did not go to precision rod bearings until 1953 or 54 depending on which specifications you are reading. The precision bearinged engines were referred to as "high pressure" engines. The earlier design used babbitt as the rod bearing material, and shims at the rod cap part line for adjusting the size. The non precision bearinged crankshaft did not have oil passages drilled in it, from the main bearings out to the connecting rod throws, the rods received their oil from pressurized nozzles aimed at scoop covered holes in the rod caps. The early engines [216 and 235] are virtually identical in outward appearance, again a search will probably yield some "how to identify" photos, hope that helps.
