Hello all, I know there are some that would say leave the 6v system, but it’s not my thing. With that said, I need some help to try to finish today. All is original. Have alternator mounted. New coil, condenser etc. My questions are, where or how do I connect coil wiring now that is going to be neg ground. I’m going to run cable battery to starter, 10ga wire from starter to 2 post junction, other side of junction to Alt batt connection. Going to setup similar to 1st pic. Second shows original diagram. So how does coil now connect and where do I place the ceramic coil resistor. Thank you for some help here...
Simple answer, distributor wire hooks to coil negative on a negative ground system, positive on a positive ground system. Resistor goes in positive wire on negative ground system. Couple questions for you- What are you using for wiring? Making your own, original or reproduction Model A? What alternator? One wire or 3 wire? Amperage rating of the alternator? Reason for the questions is it looks like the "ignition" switch in the model A diagram only functions as a switch for the coil circuit not really providing a on/off ignition circuit which is needed for the 3 wire alternator. Also the original Model A ammeter probably can't handle an alternators output.
Thank you. I’m using the Delco 10si like in the first diagram. It is a 65amp. Making own wiring, under 100amp 10ga should be ok. I will replace the ammeter. I read that somewhere also. I think it needs to be a 30amp one, model a is 20. Unsure on that, i’ll Look that up again.
This should work for you if you can use the original ignition switch as a on/off switch as shown. I've added the Model A junction block you mentioned using. The ammeter should match charging system capacity, 65 amp alternator should have minimum of a 60 amp ammeter which I doubt exists to fit an A (and even then I wouldn't trust it considering where it was probably manufactured). You may need to add a diode in the wire shown with the charge light if you find car won't shut off (unplug alternator if it does this).
Like 24 said, wiring exactly like that diagram will likely cause the vehicle to not shut off with a simple ignition switch. With an ignition switch that has an “acc” post wire the switch wire (#1) from the alternator to the accessory side, problem will disappear. Also with that exact diagram, you could experience a “slow” charging and sometimes odd charging problems. With the voltage sencing wire at the back of the Alternator (#2) the alternator sences more “alternator “ voltage that “ battery “ voltage. Most of the time it’s no problem......but sometimes it can be. Solution: run wire #2 back to the battery or starter solenoid. Just my experiences converting many old tractors. Bones
I am all done. Thanks 24 and Bones. Bringing a battery home tomorrow and looking to take first maiden run up the street. If all is good, will change all bulbs to 12v. And drive it for a while stock. After big blocks, small blocks etc, this will be quite a change but I’m kinda into it! Thanks all, wish me luck!
Ok, so I got it going! Very happy. All is working correctly except my red indicator light turns on in key off and turns off in key on. Car runs, starts stops, but light is working in reverse. I switched terminals on switch and no difference. Any ideas? I’m soooo close!
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