Forum » General Engine Building Discussion » Vane style oil pump surface - rough or polished?

Vane style oil pump surface - rough or polished?

General Engine Building Discussion

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I am rebuilding one of my motors and while pulling it apart I noticed that the oil pump pickup was cast and really needed some porting. These engines suffer from oil issues anyway, so trying to do what I can.

The oil pump is two parts, the pump and the pickup. The pump uses vanes and those vanes ride on the flat surface of the pickup. My question now is about the surface those vanes ride on, should it be rough or polished? I'd think rough to help keep oil on the surface to reduce friction on the vanes, but I'd also think polished to help reduce friction since oil is already riding on the vanes and surface as it moves and i'm sure there is clearance enough to keep a film between the vanes and the surface. The vanes are steel and the pickup surface is cast aluminum.

The surface as i removed it does show marks where the vanes ride on the surface which is what brought up my concerns and thus, my question.

Or, does it not make any difference?