How do you tighten up the rockers on a 1983 305?

To tighten the rockers on a 1983 305 engine, first, ensure the engine is at top dead center (TDC) on the compression stroke for the cylinder you're adjusting. Use a wrench to turn the rocker nut while checking for tension on the pushrod; it should spin with slight resistance. Tighten the rocker nut until you feel a slight drag on the pushrod, then tighten it an additional half to three-quarters of a turn. Repeat this for each rocker arm, following the firing order of the engine.