Pontiac V8 Engines: Valvetrain Performance Guide
With its :1 ratio rockers, Pontiac originally used a rocker arm stud that contains 7/1614 base threads, and a 7/16inch upper shoulder that tapers into 3/8inchdiameter threads. Tightening the rocker nut to 20 ftlbs locks it in place against the stud and automatically sets hydraulic lifter preload.