Abstract: A twelve-point rocker-arm adjusting nut (10) designed to be threaded into a rocker-arm stud to adjust the height/clearance between a valve and a rocker arm (44). The nut (10) consists of an axially elongated cylindrical body (12) and a hex-socket tipped set screw (32). the nut (10) has a threaded bore (20) therethrough that extends to near the lower surface (18) of the nut. From this lower surface extends upwardly a thread-free stud entry port (24). Around the upper section of the nut (10) is located a twelve-point wrenching section (26) that includes at its lower end a wrench non-slip lip 30. The wrenching section (26) serves both as a wrench gripping section and for directing oil to provide cooling for the rocker arm base and pivot ball washer (46) interface. To operate the nut (10), a standard twelve-point wrench is used to rotate the nut until the proper height/clearance between the valves and the rocker arm is achieved.