I use the "companion cylinder" method, something left over from adjusting race engines with very radical camshafts that have a very narrow window of cam lobe position that gives an accurate adjustment. It involves getting one cylinder on "overlap" where the exhaust valve is closing and the intake is just beginning to open, and adjusting the valves on the cylinder halfway around the firing order that's exactly on top dead center. It's similar to the method of aligning the timing mark, adjusting half the valves, turning the engine once and adjusting the others- - - -just a lot more accurate.
Like a lot of stuff old racers do, it might not be absolutely necessary on a street machine. We just do it by habit!
Jerry
