6-27.3. CONNECTING ROD BEARINGS - MAINTENANCE INSTRUCTIONS.
a. The connecting rod bearing shells are precision made and are replaceable with shim adjustments. They consist
of an upper bearing shell seated in the connecting rod and a lower bearing shell seated in the connecting rod case. The
bearing shells are prevented from endwise or radial movement by a tang at the parting line at one end of each bearing
b. Multiple layer copper-lead coplated or aluminum triplated bearings are used. These bearings have an inner
surface (matrix), of copper-lead or aluminum. A thin deposit of babbitt is plated onto the matrix. This babbitt overlay has
excellent resistance to friction, corrosion and scoring tendencies which, combined with the material of the matrix,
provides improved load carrying characteristics. These bearings are identified by the satin silver sheen of the babbitt
when new and a dull gray after being in service.
c. The upper and lower connecting rod bearing shells are different and are not interchangeable. Both shells are
notched midway between the bearing edges approximately 3/4 of an inch in from each parting line. The lower bearing
shell has a circumferential oil groove that terminates at the notched ends. These notches maintain a continuous registry
with the oil hole in the crankshaft connecting rod journal, and provide a constant supply of lubricating oil to the
connecting rod bearings, piston pin bushings and spray nozzle through the oil passage in the connecting rod.