To keep from trying to adjust a "dancing" rocker arm, bring the engine to operating temperature, shut it off and then adjust the valves. If you note when the rocker arms change the lift from exhaust to intake the opposite cylinder will be on the heel of the cam and will be O.K. for adjusting. When 6 rocks, 1 is ready, when 5 rocks, 2 is ready, etc. follow the firing order.
I have a tool from 50 years ago that has a socket with the screwdriver inside operated with a knob on top, it works fine for a running engine.
