Ford Duraspark II ignition question

I'm helping a buddy put a late 70s Duraspark II ignition on his 1963 straight 6 Falcon. This is the first time either of us have don't this but I've read a ton before getting into it. He is using a stock coil, dist and module off of the donor car.....a 77 model Ford.

The system is on and it starts and runs fine, I am just concerned about the power source we used. I ran a 12 volt wire that is hot with the key on under the hood for the coil and the module. I am not getting a full 12 volts, actually around 10.5 volts. It's old wiring on the car, I guess that is the reason behind the voltage drop but will that power supply be sufficient? Just want to make sure. I don't want him pointing the finger at me if something fails.

 

The duraspark likes a resistor in the power lead.. Either a resistance wire or a ballast resistor like the mopars used are fine.. If you are getting 10.5 volts while running I would think you are Okay..

 

The way I understand it is, 12v to the box. Coil depends on which one ya have. I have some with a resistor on it that takes 12v and some that require voltage to be lower.

 

Your pic shows the same as I said. Power to the module is before the resistor at 12v.

 

The Duraspark is a great unit.

What is your battery voltage? maybe the 10.5 is what the batt is?

Anyway see what you got with the ignition running and the bat voltage up to 14.2 (or whatever) when the engine is running.

I don't think it will run (fire) at less than 8 volts.

 

That's the way I wired it but no ballast resistor for now just to get it going. The battery is fully charged. The 10.50 volt reading was at the coil splice under the hood with the engine running.

 

If the 10.5 wire don't get hot, your'e good.

What's at the other end of the 10.5 wire? inotherwords is there a voltage drop along that wire? No big drop your'e good.

 

so I'm guessing no other form of resistor would be suggested at this voltage??

 

Technically, the start position on the key is what sends 12 volts to the coil, it bypasses the resistor for easier starting. In the run position, it goes through the resistor, stepped down to reduce load on the battery while driving. So as was said, if 10.5 isn't getting hot, I'd say it's ok.

 

We tinkered with the car a little more. We're hooking the coil to the existing coil power supply. Then if I am looking at the diagrams right, a 12v supply is split from the output of the ignition switch and directly to the module. Then someone told me not to do that because it would cause excessive load on the ignition switch and burn it up. Does anyone know if that's the case? Where would you recommend getting a run 12 volts from?

 

I'm pretty sure the "start bypass" on your diagram can come off the "I" (other small post) terminal on your starter solenoid. That's where the old points ign coil picked up power on cranking. Diagram shows it coming off the ign switch, but electrically it doesn't matter. Just make sure it goes dead when it's not cranking.

If you are showing 10.5 on the original coil hot lead, than the car has a factory "resistor wire" instead of a ballast resistor. Personally, I would get rid of that wire and run the ballast, but DON'T use both.