The adjustment of the distance from the cam lobe to the top of the nut (which determines your valve lash) is only accomplished when you screw the nut up and down RELATIVE to the valve. Thus, if the valve is turning with the nut on top you are not able to adjust that distance. When I first did my valve adjustment only three of the valves required the lower wrench. If the valve is stationary you do not need the lower wrench. The valve has one slot in it and the valvespring keeper has a tab which fits into it. Thus, if it is stuck then holding this is how you keep the valve from rotating with your top nut.....