Jerry,
With the advent of the changes made to the low pressure 235 engines from '49-'53, where they changed the supply of oil to the valve train to the rear camshaft bearing rather than from the oil distributor and through the water jacket, does that indicate that oil distributor no longer played a part in managing when oil was allowed to make it to the valve train?
In The Manual there is a reference to an orifice between the rear camshaft bearing and the copper line under the side cover to meter the oil supply to the valve train. The orifice likely prevents the valve train from hogging too much oil from the crankshaft and the camshaft.
I would also suspect that sludge blockage of this narrowing orifice could be the culprit for many no-oil-to-rocker-arms scenarios.
