oil pressure to rockers?

[1930artdeco]

OK, I am getting ready to fire up my long dormant engine! So I thought that I would prime the engine first and then adjust valves and set to TDC. Long story short, the PO added an aftermarket oiler system that I did not catch. That problem is fixed but my question is this: Why do I get a large amount of pressure on the drivers side and not so much on the passenger side? The pass side rockers get oil but not as much as the drivers side. Can I clamp down the drivers side rockers to force more oil to the pass. side?

Mike