[C. Clark]

Dale,
As you stated the large clamp with the wire slot in it clamps on #1 spark plug wire. The black or ground wire clamps to any good ground, I use a bolt in my engine compartment that's connected to the frame. The red or positive side can be clamp to any 12 volt source with the key on, some use the coil terminal as the heat source, I use a hot terminal / screw with wires, near my voltage regulator. If you have a multi-tester check for your hot lead with the key in the on position.
Good luck
Chas.