Our LRDG Chev

[motto]

Andrew, the FLOW to the rockers is controlled by a restrictor which doubles as a connector nipple where the oil comes out of the side of the crank case. The rockers don't need much lubrication, they certainly don't need pressure, just the presence of oil is enough.
Engine oil PRESSURE is pretty much controlled by the distributor valve which creates a back pressure in the same manner as a relief valve.Of course engine wear also plays a part when the engine has been in service.
Oil tapped off from upstream of the distributor valve feeds the main bearings, camshaft bearings, timing gears and rockers.
Oil that passes through the valve supplies the sump manifold for lubrication of the big ends.
It sounds complicated but it isn't really.

David