The filter base on the engine is supposed to have a tube extending from it which comes to a point with a restrictive, small hole in it.
You are supposed to pull the stick out of the new filter (which serves to keep the hole open in the filtering media during transport and storage) out and discard it and drop the filter down over the hole tube and down onto the base.
Often times, the steel tube becomes detached from the filter base and remains in an old filter and gets tosses, as it seems your"s has.
WITHOUT the tube you are filtering NO oil and the oil pressure is less "cuz the restriction provided be the small hole in the end of the tube is gone!
Here"s a couple of photos of (similar) Allis filter bases, one with the elusive tube and the other missing it"s tube.