The Ford Barn

pjdeb · 10-16-2023, 07:09 PM

I am about ready to pull the engine on my 1923 T. It has been sitting for 30 years.

When it was running last, it was running on battery. My questions are:

1. By 23 the T had battery, starter, and generator. Why did Ford continue to include the magneto?

2. What are the pros for running on magneto?

3. What are the cons for running on magneto? I have seen videos where there is a lot of coil arcing.

Thanks. Trying to decide if I should replace the magneto or just take it out and install the splashers.

rotorwrench · 10-17-2023, 01:26 PM

The battery is or was a backup originally. Dry cell batteries were an option even before they had electrical systems.

Some folks convert to distributors but they lose the trembler coils. No more free starts with a distributor.

oldmotorsguy · 10-31-2023, 08:15 AM

1. Just speculation, but Henry Ford at this point was driven by cost, and not necessarily by what makes practical sense. He eliminated the magneto 5 years later, and by doing so saved money by getting rid of the coil ring and the magnets, a significant savings. But in 1923, he was likely thinking, 'if it ain't broke, don't fix it.' His magneto was part of his original engineering, and it was the horse he rode in on. I would bet Edsel suggested dumping the mag, and he got his way a few years later.

2. The pro is that the AC power provided to the ignition system by the mag had more energy and was more efficient than the battery, and the points ran hotter, better spark, etc. That, and it did not drain the battery, although that amount of draw to power the points is not all that much, really.

3. Con: the weight added to the spinning flywheel owing to the 16 magnets would bog down the RPMs to a degree. If you remove the magnets and instead install some splash fins in place to aid in lubrication, you can really tell the added 'snap' when you rev the engine, and the general rule applies: less weight, more power.

I have owned Model T's both with and without the magneto. I would say leave it in place, as that is the way Hank designed it, and he was a fairly competent engineer back in the day.

mechanicalarts · 12-05-2023, 02:15 PM

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Search "The Model T Ford Ignition System" on fordmodelt.net. Its a great article that explains just how clever the model t ford ignition system was.

The article explains it better than me, but when running on magneto, the wave length of the current actually changes timing with engine speed, resulting in slightly better performance. Also, its firing your coils at much higher voltage. A Model T ignition system running on magneto in good condition will outperform a Model T ignition system running on a 6 or 12 volt battery any day.

10-16-2023, 07:09 PM	#1
pjdeb Senior Member Join Date: Sep 2019 Location: The Villages, FL Posts: 103	Magneto Advice Needed I am about ready to pull the engine on my 1923 T. It has been sitting for 30 years. When it was running last, it was running on battery. My questions are: 1. By 23 the T had battery, starter, and generator. Why did Ford continue to include the magneto? 2. What are the pros for running on magneto? 3. What are the cons for running on magneto? I have seen videos where there is a lot of coil arcing. Thanks. Trying to decide if I should replace the magneto or just take it out and install the splashers.

10-17-2023, 01:26 PM	#2
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,436	Re: Magneto Advice Needed The battery is or was a backup originally. Dry cell batteries were an option even before they had electrical systems. Some folks convert to distributors but they lose the trembler coils. No more free starts with a distributor.

10-31-2023, 08:15 AM	#3
oldmotorsguy Senior Member Join Date: Jun 2010 Location: Crossville, Tennessee Posts: 157	Re: Magneto Advice Needed 1. Just speculation, but Henry Ford at this point was driven by cost, and not necessarily by what makes practical sense. He eliminated the magneto 5 years later, and by doing so saved money by getting rid of the coil ring and the magnets, a significant savings. But in 1923, he was likely thinking, 'if it ain't broke, don't fix it.' His magneto was part of his original engineering, and it was the horse he rode in on. I would bet Edsel suggested dumping the mag, and he got his way a few years later. 2. The pro is that the AC power provided to the ignition system by the mag had more energy and was more efficient than the battery, and the points ran hotter, better spark, etc. That, and it did not drain the battery, although that amount of draw to power the points is not all that much, really. 3. Con: the weight added to the spinning flywheel owing to the 16 magnets would bog down the RPMs to a degree. If you remove the magnets and instead install some splash fins in place to aid in lubrication, you can really tell the added 'snap' when you rev the engine, and the general rule applies: less weight, more power. I have owned Model T's both with and without the magneto. I would say leave it in place, as that is the way Hank designed it, and he was a fairly competent engineer back in the day.

12-05-2023, 02:15 PM	#4
mechanicalarts Junior Member Join Date: Dec 2023 Location: Tenants Harbor Maine Posts: 13	Re: Magneto Advice Needed Sponsored Links (Register now to hide all advertisements) Search "The Model T Ford Ignition System" on fordmodelt.net. Its a great article that explains just how clever the model t ford ignition system was. The article explains it better than me, but when running on magneto, the wave length of the current actually changes timing with engine speed, resulting in slightly better performance. Also, its firing your coils at much higher voltage. A Model T ignition system running on magneto in good condition will outperform a Model T ignition system running on a 6 or 12 volt battery any day.