If the clutch is dragging,it may not let the motor turn fast enough to fire off. Im not sure on the clutch adjustments on the fords,but Ive seen a few of the older motors have this problem. Just for giggles,make sure its in neutral when cranking,just in case this is the issue. And also,showing 7 volts,I assume it is a 6 volt system,Ive seen some guys run a resistor inline with everything except the starter,and go with a 12 volt battery,just for starting the engine.