Con rod query

[Chris KC]

Unless finished in place all shells are made with an exaggerated clearance at the parting line although it may not be obvious.

Bob, surely you mean interference? (or 'crush' as it's known in the trade). The shells stand a few thou proud of their housing so they are forced firmly into it on assembly. It is this radial force (not the tabs) which prevents the bearing shells turning in service.

I think what Bob is referring to here is the fact that big end bearing shells aren't usually a uniform thickness, they are thinner near the split line, so will present an oval hole giving greater side clearance to the crankpin 

Ah, I see. In that case he is quite right (sorry Bob).