MTFCA Forum

My Lizzy is starting fine on battery (6V). Especially with electric starter it needs only a few seconds, even on cold start. Then I can switch to Magneto and it runs even better/smoother.
I made an electronic battery charging for charging battery from Magneto (with shut-off when battery is full and current limitation to a few amps to not cause too much load on magneto), this also perfectly works. (So Magneto is in good condition, I assume.)

What I never got working is starting on Magneto. This is more academic, but would be good to know...
Even with electric starter and warm engine, the engine is turned and turned, but it does not fire. For sure it is turned too slowly. When switching to battery, the engine immediately starts.

Do I have to set something different? Spark advance, i.e.? On battery-start, I have the advance lever in uppermost position and throttle downwards 3-4 notches.
I am a bit scared about cranking around with one or two hands to get sufficient speed, but the half-turns normally done by one hand seem to be not sufficient.

If somebody has an idea, suggestions are welcome.

Rainer, prime your cylinders by choking and turning the engine over a few times with the switch off, then turn switch to mag, starting on mag you may have to pull your advance down a few notches, each T is different so you have to experiment some so your not moving the lever down too much. Fair warning if you move your advance too far down it may kickback. You need to learn to hand crank with your left hand & not wrap your thumb around the handle. Once you find the sweet spot you’ll get more confidence, just remember to only move the lever down just a few notches.
Also you may need to fine tune your commutator position Steve Jelf has a great write up on that on his webpage. Attached is the link. Best John
https://dauntlessgeezer.com/DG97.html

You must advance the spark lever 2-3 notches to start on mag. Everything else is the same as if starting on battery, that is for hand cranking or using a starter. I recommend starting on battery and switching to mag after it starts.

The engine should not need to be spun in order to start on magneto. I don't think the battery charging device would load the magneto enough to make starting difficult, but disconnecting it temporarily would show whether it does or not.

Hi, TXGOAT2.

The charging device rectifies magneto output and then uses a MOSFET and a 24V bulb towards the battery. The bulb is a "series resistor" with rapidly increasing resistance (so it is lots better than a normal resistor, having a constant resistance) and is shining ~30-40% of full brightness. But circuit has to be closed first by the MOSFET, which does not happen.
Simple math: 28V AC (Magneto) - half-wave rectified (giving an average of 14V) minus 6V (Battery) gives something around 8-12V in fact (for the bulb). This matches the brightness of bulb I see. So the loading current is limited to estimated 0.7-1 A max. on a running engine, far below of what magneto can produce, and there is always one half-wave without load (because of half-wave rectification), too.

I remember well -- I was not able to crank-start on magneto even before installing this charger (the charger is also my direction lights "blink-relay").

Also I think:
Using the electric starter with ignition on magneto ... The starter will be powered from battery, load on magneto is less than 1 Amp, so this should leave sufficient voltage for the coils, no? I guess the rotating speed of electric starter will be approx the same as when cranking by hands?

Interesting that some one questions starting a Model T via handcrank and magneto.

Starting a Model t should be no problem. When you consider some on the forum who are still vertical and on the green side of the grass have started such motorized vehicles as a Farmall F-30. A 283 cuin motor with 33 HP magneto ignition and hand crank only.

No compression release. Fuel gasoline, kerosene, or related distillate. Close enough to a Ford Engine.

Jeff Humble is correct. Let me explain.
If you try to start the Model T engine with the spark lever fully retarded the first current pulse to the coils will occur at 26.5 degrees ATDC. By that time the piston is already on its way down the cylinder and much of the compression wil have disappated so the engine will be dificult to start. By advancing the spark lever 3-4 notches (which Ford recommended) the first spark will occur at 4 degrees ATDC making the engne easier to start and run.
When the Model T magneto was developed the magneto obvioulsy had to produce current pulses to the coils at time that would allow easy starting and
an adequate to spark advance for normal operation. The initial advance setting at 15.5 degrees ATDC provided for both situations AND provide with a modicum of protection for battery starting if a Model T owner added batteries to the pre 1919 cars ignition system. Ford never supplied ignition batteries from the factory. Notice the recommended (magneto) spark lever starting position.
Over twenty years ago Steve Coniff and I co-wrote the following article for the Model T Times Magazine explaining all this in greater detail. When reading, pay close attention to Figures 4 and 8 noting, the magnets are mounted on the flywheel advanced 7 degrees ATDC.
Hope this helps
Ron Patterson

Sorry about including the starting instructions twice.

With the spark lever in the proper position & a good, hot magneto, all it takes is a brisk 1/4 turn to start.
Your T will run on mag, but what is the output? Mine measured 30-32 volts with the rectifier in place & 35 without.

At best, magneto current and voltage are at a minimum when crank starting. ANY unnecessary load may interfere with starting, and that includes coils that are not in good adjustment. Plugs in poor condition or with excessive gap can make starting on magneto more difficult.
As noted above, a brisk pull on the crank should start the engine on magneto, assuming the mixture is correct.

A magneto that is even a little weak can complicate starting, even though the car runs well on magneto once started.

My car has been sitting for several days. I went out just now and tried to crank start it on magneto. Temperature about 84F, car in good condition, 10W30 synthetic oil, ECCT adjusted coils, WalMart gasoline. After turning the key to magneto, I set the spark just over 1/4 of the way down and the throttle about 1/3 of the way down carb adjustment 1 1/8 turns off the seat, pulled the hand lever back firmly, then engaged the crank and pulled the choke wire out and gave the engine 2 pulls. I then released the choke and gave another brisk pull and the engine took off and kept running. It would probably be a different story on a cold morning, but I think I could start it down to around freezing with 0W20 oil in the crankcase and a little more choking. If I flooded the engine, I'd turn the key OFF, then open the throttle half way and spin the engine for half a dozen full turns or so, then turn the key on and try again.