The Stovebolt Site Forums The Shop Area The Electrical Bay 59 Basic Wiring and a bit more with the new HEI

59 Apache 1/2 Ton Stock 235 with a new HEI distributor with stock appearance round coil that comes with the HEI.

I have determined (with help) that my new mini HEI distributor does NOT use the OEM style ballast resistor. My new Stock harness was adjusted to remove the ignition wire and coil wire from the resistor and left taped up in case I need to go back original.

Now for the electrical education you can give me as I am providing power to the new Distributor Coil as the instructions provide. They just do not give me quite enough information for this application:

Instructions call for a 10 gauge(mandatory) wire to the coil. I surmise from the information I received as well as this from Jerry that it is a good idea to follow the instructions!

The GM HEI coil has such a low primary winding resistance that it's necessary to use a big wire to allow it to come up to full charge on the magnetism quickly. Once the magnetic core is saturated properly, they use a combination of the inductive reactance of the coil windings and a built-in current limiter to prevent overloading of the transistor amplifier in the ignition module.
Jerry

Makes sense to me as it sounds scary to not use the 10 gauge. Here are the basic questions:

1. The 10 gauge wire will go to the coil from the ignition switch (I assume it has to) but the wire bringing power to the ignition switch comes from the Ammeter right? And that is not 10 gauge. Does that matter or does the 10 gauge only need to begin at the ignition switch?

2. I do not think there is a fuse anywhere in this story so is it a good idea to fuse that 10 gauge wire between the switch and the coil? If so, what amp in line fuse should I put in?

3. I have the foot stomp 3 pole switch. BATT, ACCY and START. The 10 gauge wire will be on the START terminal along with the gas gauge wire. The ammeter wire will be on the BATT terminal and a couple of things like signal flasher will be on the ACCY. Any issues with that setup.

As I do not have a real skilled background in the wiring, I made great use of the numbered instruction sheet that came with the Carter supplied original harness. This HEI/Coil application calling for the 10 gauge wire does not really say from where or to what extent the 10 gauge wire must be used. I want to make ZERO SMOKE here. I like the new stuff I bought and do not like the smell of burning insulation. Any advice on this for me. I still have to power the optional fuse panel also but I want to get this ignition circuit squared away first.

Thanks
Ralph

Ralph,

It sure seems like massive overkill to run such a large wire to the coil, but I'm not an electrical engineer.

What would prevent you from using a 10 gauge wire from ammeter to keyswitch BATT and another 10 gauge wire from keyswitch ON to your new coil. It isn't SOP to fuse this circuit.

I am wondering if the electrical characteristics that Jerry outlined for the big conventional GM HEI with coil-in-cap apply to your mini unit with stand alone coil.

I have seen some huge 80,000 volt coils and they sure didn't have a 10 gauge wire feeding them....but what do I know.

Stuart

The 10 gauge seems larger then ness. to me too but like you say lets follow instructions. It would not be ness. to change rest of the wireing. Do not put a fuse in the ign. cicuit. You might put a fuseable link in the main power feed & alternator if you are useing one. If you are using a foot starter you don't use the start term on the ign. switch. The ign. term goes to the coil & gas gauge. Hook the acess. to the accy term. Put fuses on them.

The incoming wire to the ignition switch needs to be big enough to carry all the load on the switch, including the coil, so it needs to be 10 Ga. or larger all the way to the battery cable connection at the stomp switch. It makes no sense to have a large wire for only part of the circuit. If that concept worked, we could supply a fire engine with a garden hose from the fire hydrant to the pumper, and go with 2 inch hoses from there to the fire.

The 10 ga. wire probably IS overkill, but that's the way GM built millions of original-equipment HEI systems for 20 years or more. The wiring from the fuse block or fuse link to the ignition switch was 10 ga., plus the power wire to the coil was the same size. That was on remote-coil applications, and coil-in-cap systems, too.
Jerry