Abstract: A piston or diaphram and a pump manifold assembly having an adjustable ball valve is disclosed. The manifold comprises first and second flanged chambers for mounting to the pump, a conduit or passageway which joins the two chambers and ball valves positioned in and near the first flanged chamber. The ball valves allow the manifold to pump materials of various sizes without the problems associated with the prior art. As specifically disclosed, the distance the ball may travel in the first chamber is controlled by at least one shaped pin positioned in the area of the valve which is easily removable without the need for disconnecting the manifold from the pump or without removal of the balls from the valves. By use of the pump and pump manifold assembly of the present invention, a continuous flow of material of varying sizes can be achieved without substantial surge. In addition, the assembly is easily cleaned, repaired and modified without the need for complete removal from the pump or expensive equipment.