on a 305 motor, do the main bearings have anything to do with a low oil pressure problem. I think I found the low oil pressure problem the oil pressure switch was leaking oil on to the transmission. Some one told me the low oil pressure could be from a bad main bearing. Could this be.

 

A bad main or rod bearing will have excessive clearance.
When excesive clearance is present, the oil is allowed to leak out at a much greater rate than normal, decreasing oil press to the rest of the eng.

How low is the press at idle and at crusie RPMs?
Did you measure the oil press with a direct reading gauge that's known to be good?
Is it knocking?

The oil leak at the press switch is probably just making a mess.

 

what are you calling low oil preasure? i doubt if bad mains would cause a majot problem, i'd make sure what the oil preasure actually is, use a mechanical gauge screwed into the block. if it's low i'd suspect a failing oil pump, the cam bearings, then mains.