How do you adjust the rocker arms on a 455 Oldsmobile engine?

To adjust the rocker arms on a 455 Oldsmobile engine, first, ensure the engine is at top dead center (TDC) on the compression stroke for the cylinder you’re adjusting. Loosen the rocker arm nut and turn the pushrod until you feel resistance, then tighten the nut until it makes contact with the pushrod. Finally, turn the nut an additional 1/2 to 3/4 turn to achieve the proper preload. Repeat this process for each cylinder, following the firing order.