The MSD box connects directly to the battery. Large Red Wire = Positive. Large Black Wire = Negitive. (I actually connected the + to the junction behind the battery). Small red wire to red wire from the dist. and a switched power supply from the igintion switch.Small white to the black wire from the dist. Orange to the + side of coil, and black to the - side of coil. There shouldn't be any other wires connected to the coil. Your tach lead should be connected to the feed on the MSD box.