A rocker arm mounting stud assembly having a rocker arm mounting stud with adjustable rocker arm fixture mounting for use with a matching trunnion. Further provided is a radius roller tip rocker arm providing a third dimension principle by making the contact point of the diameter of the roller tip, a radius, lean on its pivoting access to control misalignment away from a two dimensional plane. A teaching of rocker arm geometry is provided for establishing precision measuring rules to facilitate the correct and precise installation of the rocker arm. Further provided is a one piece stud lock providing a direct pressure method of holding each rocker arm mounting stud with precise force providing overlapping components for retainment of each rocker arm mounting stud in a precision set predetermined position.