NC30 - Engine assembly tips + Main Bearing question

[magg]

An old thread but relevant to my question, have crunched the numbers for bearing shell thickness and crank and rod bearing sizes and OEM spec oil clearances. Results for rods are within Honda's spec range, however, main bearing oil clearances are too tight. Given the rarity and cost of new shells I would like to have some confidence in Honda's selection process and not have further doubts raised by the inconsistencies Honda's published figures.

How have others solved this problem.

[JC120]

Odd that your mains are too tight. Usually it's the other way around. I've never noticed any inconsistencies in Hondas bearings selection so it's difficult to understand what you mean.

[magg]

As I said if you take the dimensions from the service manual for the various components that determine the main bearing oil clearance and do the calculations the result falls outside Honda's oil clearance spec. This discrepancy somewhat undermines the shell selection process based on their colour code, particularly when rod bearing calculations work out correct. Testing oil clearance by measurement may be considered the final arbitrator but given the rarity and cost of bearing shells is would be nice to start with faith that the colour to clearance connection is valid.