[Jack Shaft]

You use a pointer and a degree reference for the crankshaft pulley, nurex has them. Then use a cheapie tach dwell meter ,it reeds rpm off of the points. Once those two are set rig the timing light and start the engine.. The strobe from the light on the pointer will tell the nurex advance.. per rpm.. the model a ford engine performs optimally at 1 degree advance per 100 rpm...so at 500 rpm or idle,5 degrees, it should read 10 degrees at 1000 with a maximum advance at 24 degrees..By check the advance at various rpms you are basically mapping the timing..something I would definately do with the gyro,