An apparatus and method for adjusting the axial position of a valve pin in an injection molding system, the apparatus comprising: an actuator comprising a housing having a chamber enclosing a drive member for driving a valve pin along an axial path of travel, the actuator housing slidably mounted and adapted for controlled upstream and downstream movement of the drive member along a path complementary to the axial path of travel of the valve pin, a mounting plate and an axial position adjustment screw screwably mounted within the mounting plate upstream of the housing of the actuator for controllably moving the valve pin to selectable starting or ending injection cycle axial positions.