Valve adjustment procedure on Chevy 305?

Answer 1

With the engine at operating temp, remove a valve cover and start the engine (Note: there will be oil coming out of the pushrods and spraying onto the exhaust manifold, so work quickly). Using a ratchet with a fairly long extension, one at a time, slowly back off the rocker nut until the lifter starts rattling. Slowly tighten the nut until the noise stops, then at 1/4 turn intervals, tighten the rocker nut down one full turn. When all 8 are finished, kill the motor, install the valve cover, then repeat the procedure on the other side.

If the heads have just been installed, they are adjusted with the engine off. Turn the engine to TDC #1 (aligning the timing mark, but ensure both valves are closed - look at #6 - they should have the exhaust valve just closing and the intake opening, #3 should have its intake open), then work on the #1 valves. Back the rocker nut off until the pushrod is loose, then tighten the nut until the pushrod no longer can be spun freely, then turn the nut one full turn. Do that to both the #1 intake and exhaust. Turn the crank 1/4 turn, then repeat for #8. Turn the crank another 1/4 turn and repeat for #4, then 3, 6, 5, 7, and 2. If it was done properly, they should be exactly correct with an engine running adjustment, but it is wise to check them all with it running.