hard stop oil pressure drops to zero

[rotorwrench]

There is not much for baffles in those old oil pans. A hard turn or stop can allow all the oil to go forward or side to side. If the pick up screen loses the oil, it will draw air and that could be a problem for a bit. At least till it gets a shot of oil again and pushes the air bubble out.

Changing out an early pump for an later type can require a change in the oil pick up assembly if anything like that has taken place.