My 312 came with the external oil lines to the rocker shafts already installed. The oil pressure switch is on the end of a tube that extends a few inches out from the block. Threaded into this tube at 90* is a valve with the oil line heading up to the rockers, so that the flow to the rockers could be shut off or reduced with the valve.



The oil pressure light is on at idle speed, and while there are plenty of potential reasons why oil pressure might actually be low, it seems to me that having the switch located on a line that leads to two relatively large openings (the oil overflow tubes at the ends of the shafts, not to mention all the rocker oil holes) might give a false low reading. Currently the valve to the rockers is wide open and there is a good stream of oil that flows out of the overflows.



I'm thinking the flow to the rockers could be reduced which should elevate the pressure reading at the switch. But how much flow is enough?

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive