Got myself into a bit of a predicament replacing rod bearings. Sent the crank to APE for lightening and balancing "before" making note of the rod bearing codes marked on the crank. Now that I'm putting the motor back together I'm trying the get the right clearances. The existing bearings Plastigage from .0018-.002 under the .003 limit. One of the pairs is scored enough to catch a fingernail slightly so I figured I would replace all of them since APE micro polished the crank. Then, I mistook the "C" marking on the rods for the bearing code instead of the weight codes. So, I ordered and received all "C" bearings.
The new C bearings Plastigage with a greater clearance of .002 to just under .003. The rod journals are 1.2587/1.2590 or 31.97-31.98 mm according my digital caliper. Three of the rods are marked with code "2" and one is marked "1" so according to the chart that means I should have "B" shells for the three "2" rods and a "C" bearing for the "1" rod.
My questions are:
1. Does the scored bearing need to be replaced or what you recommend on using existing vs. new? Am tempted to just put it back together by polishing out the groove.
2. What should the as new factory clearance be? Can only find outer wear limits…
In any case, looks like I'll be sending back three pairs of the C bear shells.
Thanks!
Andy --
