That method is terribly messy and inaccurate, too. It's much simpler to do the adjustment with the engine stopped. Just be sure the cylinder you're adjusting is on top dead center with both valves closed. Either use the distributor rotor to indicate which cylinder is ready to fire, (top of the compression stroke, both valves closed), or use the "companion cylinder" method I've described several times. You couldn't bribe me to do a running adjustment on a hydraulic-lifter engine!
Jerry