there's a check ball in the oil gallery above the pump which directs the oil thru the filter--the chech valve in the filter adapter will restrict the oi l from going back thru the filter and the pressure will go to the center galley where it will feed the mains vis the grooves behind the cam bearings and the rods will be fed from the mains---lifter galley and valve train will be fed from the rear cam galley outward to the two galleys that feed the lifters then up to the valve train--this actually better than some of the preoiler pump drivers as the side the distributer i s on is pressurized also instead of just dumping the oil at that spot---