Ford Model A Coil Positive Side Wiring Diagram
By Fred McDonald on Monday, May 09, 2011 - 04:28 pm: I am currently building a Model T speedster with a distributor and a reg. coil. Does anyone have a diagram of how to wire the car with this conversion? Thanks for any help or suggestions.
By John Faccin - Crystal Falls, Michigan on Monday, May 09, 2011 - 06:10 pm: The lead out of the distributor go to the negative side of the coil, and the positive goes to your ingition swich the side that gets hot (power) then you turn the key on.
John
By John Faccin - Crystal Falls, Michigan on Monday, May 09, 2011 - 06:12 pm: Sorry about the spelling my meds are all out of wack today. I'm not seeing straight.
John
By Stan Howe Helena, Montana USA on Monday, May 09, 2011 - 08:27 pm: That's a fine looking speedster project. If you are running 12 volts you will need to install a ballast resistor in the hot lead to the coil or it will fry the points. If you are running 6 volts it is a good idea to run a 6/3 volt ballast resistor in the hot lead to keep the coil voltage under control and avoid burning points.
By John Faccin - Crystal Falls, Michigan on Monday, May 09, 2011 - 08:43 pm: Stan, I have seen some coils with the resistor built in, so it would be best to check the coil first before putting in a resistor.
John
By Fred McDonald on Tuesday, May 10, 2011 - 05:44 pm: Thanks guys. My distributor is a 6 volt and has a resistor built on the side of it. Hope that's what it is? Anyway, I was wondering if anyone had ever done this and I know the wiring is different so a diagram would be helpful. In the mean time, I talked to Don Lang and he gave me a wire by wire rundown of how to hook them up. Any other comments would be helpful. Thanks
By Frank Harris on Wednesday, May 11, 2011 - 12:24 pm: Fred, Here is the good wiring diagram you requested. The thing on the side of your distributor sounds like it is the condenser otherwise known as the capacitor and keeps the points in good order. It should be silver colored and have a wire coming out of one end like a fire cracker fuse. It should be mounted on the side of the distributor.
The voltage drop ballast resistor is always mounted between the ignition switch and the coil. Sometime the ignition is wired with a two position turn key so that when you go to start mode you get full battery voltage at the coil for better starting and then when you release the key you power the coil with a lower voltage in order to save the points from burning. In the diagram it shows the switch in the running position and when the engine starts the switch is pointing down and the coil gets full battery voltage. This is done because battery voltage drops when the starter is engaged.
I always like to run a jumper wire from the distributor body to the engine block for a good ground because oil will get up in the tube and will not make a good electrical connection when the distributor rotates for advance - retard. But you are mounting on a cross drive so will not have crank case pressure to deal with, but I still like a secondary ground wire as shown in my picture below. The blue wire attaches to a cap clip screw and then picks up a screw or bolt on the engine or frame for a good ground. Frank
By Royce Peterson on Thursday, May 12, 2011 - 06:55 am: Fred,
I bet that is a capacitor on the side of the distributor. Resistors are typically not used with 6 volt systems.
The resistor is used in most 12 volt distributor systems so that when cranking the resistor can be bypassed to maintain input voltage at a higher level.
By Neil Kaminar on Thursday, May 12, 2011 - 09:54 am: Fred,
If you are running 12 volts and want to use a resistor, run the bypass from the terminal on the starter motor. That way the switching is automatic every time you use the starter.
Neil
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