I will suggest that you mic the I.D. of the bearing holes in the connecting rods you have.  There are two different Honda rod bearings with each having two slightly different O.D. measurements.  The journal measurements are the same for each though.  For the Eagle and Cunningham connecting rods using the Honda rod bearings, I use the Mahle/Clevite CB1780H, CB1780HX, CB1780H-001, or the ACL 4B1912H, 4B1912HX, 4B1912H-.025.  While the 1780H is the std bearing, the 1780HX has an additional 0.001” clearance while the 1780H-001 has 0.001” less clearance.  The uppers and lowers on these bearing sets can be mixed so that 0.0005” changes in oil clearance can be made. The Oliver parabolic beam rods I have for the Y (6.750” long) use the other part number bearing with a different O.D. and that part number currently eludes me.  The other option is to call Carrillo and get their recommendation for a bearing number.

I will typically target for 0.020”-0.025” rod side clearance for a street engine.  No problem with 0.030” though for a more performance minded engine.  When grinding the crankshafts to a smaller journal so that they can be offset ground, I will aim for no more than a 1.810” journal width on the cast cranks to keep from intersecting the oil supply holes going through the journals at the journal edges or filets.  Steel cranks seem to be more prone to exposing the oil holes at the filets when widening the journals so be cautious about that.  Cutting the crankshafts to the full width to accommodate unmodified 0.940"-0.945" rod widths when using the wider aftermarket rods increases the chance for the oil holes to be exposed at the journal edges and especially when grinding the crankshafts for the Honda rod journal.

With that 1.810” journal width number in mind, the connecting rods are cut so that they are 0.895” wide for 0.020” rod side clearance.  For the Engine Masters competition engines, rod side clearance is targeted for 0.100” or more and then the wrist pin end of the rod is shimmed accordingly so that the rods do not connect each other and/or the journal edges.  In this instance, any metal to metal contact is being minimized.  Keep in mind that the connecting rod side clearance has no effect on the oil pressure so excessive clearance is not a player in that regard.

Lorena, Texas (South of Waco)

Getting ready to have my crank offset ground. What is the maximum allowable side clearance? Crank will be ground to 1.85" journal, 3.6" stroke. I have a set of Carrillo rods with a big end width of .890". Im assuming that if you add the width of two rods together it gives you 1.78". With the crank journal width being 1.81" and subtracting the big end width of the rods that leaves me with .030". Is that too much side clearance? Also, what rod bearings are used with these rods? My research has led me to Clevite CB-1780H STD bearings. Thanks for the Help!

DiLL