The distributor is driven by the camshaft and in turn, it drives the oil pump. If you remove the distributor, you sill see that the bottom of the shaft looks like a large slot screwdriver. If you put a shaft with a similar end in a drill into the distrutor hole and seat it into the oil pump, you can turn the pump and generate oil pressure. You could do this and watch for oil to run out the rocker arm shaft.
