Big end bearing shell orientation

[2cams70]

Hi Guys,

When one is using aftermarket connecting rods with no oil hole provision is it better to install the shell half that has been drilled for the oil hole on the upper or lower half of the big end or doesn't it matter? I'm kind of thinking it would be better to install it in the lower half because that side of the bearing is less stressed and the hole does potentially disrupt the oil film.

[nmauduit]

I would think top and bottom take most of the pressure, either when pushed or pulled by the piston or by the rod...

[rgh0]

I dont think it really matters in practice. The top shells in my racing engines show signs of wear sooner than the bottom shell but the difference is small. The top shells see load when you are reversing the piston at the bottom of the stroke. The bottom shells see load when reversing the piston at the top of the stroke but this is assisted by cylinder pressures which reduce the loads a little on the bottom shells.

The last set I fitted had holes in all the shells so I had no choice in any case.

cheers
Rohan