MTFCA Forum

Hi all,
My wife and I inherited a 22 T Touring from her late father. I know that this car used to start/run on magneto. By the time we got it, it had been sitting for about three years, and her father had added a distributor. The car starts and runs on battery and electric starter, but I can’t get it to run when switching over to magneto. Do you think adding the distributor meant there was a problem with the magneto, or is there something else going on? Appreciate any advice.

Go look and see if there is a wire connected to the top of the magneto post. If it is gone he disconnected it. If one is there trace it up to the firewall and see if it is connected there also.

To answer your original question, you cannot power a distributor from the magneto. It was designed to power Ford ignition coils in the coil box. A simple reason is the output of the magneto is AC, not direct current and the voltage varies with engine speed. A distributor coil ignition system requires either 6 or 12 volt direct current.

The addition of a distributor is almost always evidence that there was/is a problem with the magneto. The problem can be as simple as the magneto needs to be re-magnetized which can be done without tearing into the innards of the magneto, or it can be more serious which will mean the removal of the engine and hogshead. The distributor requires a six or 12 volt car battery. If the car is not equipped with a generator you will have to recharge the battery between trips. If your T has a self-starter it should have a generator.

MichaelPawelek wrote: ↑

Sun Sep 12, 2021 11:41 am

Go look and see if there is a wire connected to the top of the magneto post. If it is gone he disconnected it. If one is there trace it up to the firewall and see if it is connected there also.

Yes, wire is attached to the magneto post and runs to the firewall. I don’t notice any breaks in the wire.

Car does have a generator as well.

I would guess that the "Mag" Terminal on your ignition switch is disconnected. Does your car still have the original type coils mounted? You can test the magneto to see if it is functional.

A little OT, but a word of caution to those who buy a T with an aftermarket ignition system! The previous owner of my T installed a Truefire (which works fine and I have retained), but he also ran a jumper from the bat to the mag terminal on the back of ignition switch so that the car runs with the key in either position.

That jumper needs to be removed if I ever switch back to stock ignition, or the battery current will discharge the magneto magnets! :O

If the distributor sits where the timer was, which they almost all do, there is no way to ground the coils. Would take some engineering to make a car run on both a distributor and a coil box.

TXGOAT2 wrote: ↑

Sun Sep 12, 2021 1:11 pm

I would guess that the "Mag" Terminal on your ignition switch is disconnected. Does your car still have the original type coils mounted? You can test the magneto to see if it is functional.

No coils; it has a distributor cap with rotor and points and what I assume is a six volt coil.

When running, test the mag output terminal for AC voltage with an analog meter or period meter.

Dan McEachern wrote: ↑

Sun Sep 12, 2021 12:04 pm

To answer your original question, you cannot power a distributor from the magneto. It was designed to power Ford ignition coils in the coil box. A simple reason is the output of the magneto is AC, not direct current and the voltage varies with engine speed. A distributor coil ignition system requires either 6 or 12 volt direct current.

Dan got this one right. Since the car was converted to distributor, it cannot run on magneto. Your magneto might have a problem, or it might not. Unless you plan on removing the distributor and converting the car back to coils and timer, the status of your mag is not important. In case you’re curious, you can test your mag output while the engine is running as suggested above.

What Brand/model distributor is it? A period correct distributor such as the American Bosch 600 is documented on running on one buzz coil and magneto. Not sure of the other popular ones of the time. The instructions for the Bosch 600 do say not to use the Bosch Coil and run on magneto. As stated above changing the ignition system to use a distributor and run on battery is a good sign that there are issues with the magneto. It could have even been removed. So pictures and answers to the questions (coil box, modern or buzz coil to the distributor, etc). There are also some additional reasons why there is a distributor besides Magneto issues: a set of new coils may have prompted the switch or if its a Bosch 600 it has centrifugal advance to no need to play with the spark leever Here are the setup's - don't see why it wouldn't work for any distributor made for a T. There are some discussion on the internet on setting up a automotive coil to run on AC. Basically it involves using a dimmer capacitor and coil (similar components to a buzz coil)