Relay to Ignition Coil Wiring Schematic

One problem with NOT using a relay is that harness/ switch/ bulkhead connector voltage drop causes battery overcharging.

Electrically (you can upgrade the wires, I'm referring to electrically / functional / as stock)

You cut the blue "ignition run" IGN1 coming out of the bulkhead and feed the end coming from the bulkhead connector to the relay coil 86

The ground for the relay coil, you can also run to ground through a hidden switch and create an anti theft "simply." 85

30 come off the start relay "big stud" through a nice big fuse and heavy duty fuse holder, 20-30A or a breaker, that is your main power feed

Then electrically, the other cut "ign1" going to the underhood harness goes to the switched contact 87

NOTE THAT if you still have the ammeter, this change will move it "wrong" by whatever amount the alternator field/ regulator and the HEI draws