Model T ignition coil

[Gen III Antique Auto]

Doing a deep dive into the Model T Ford Ignition coil. This is Episode #1 - #2 comes out tomorrow. Hope you like it!

 

https://youtu.be/JvzjURMQNuE

 

[Rusty_OToole]

Funny you brought up the Ford ignition. I just looked at a cowl from a Model T sedan or coupe. On the firewall were 9 ceramic insulators that I guess are for the ignition? Wonder what they are all  for since the Ford is a 4 cylinder. The rest of the car is gone, a friend found the cowl in a junk yard and brought it to my shop.

[Chris Bamford]

Rusty… four lower terminals to the four spark plugs, four uppers to the end-of-cam commutator, and the ninth is power in to the four coils (common terminal strip in bottom of the coil box). 

[Rusty_OToole]

2 hours ago, Chris Bamford said:

Rusty… four lower terminals to the four spark plugs, four uppers to the end-of-cam commutator, and the ninth is power in to the four coils (common terminal strip in bottom of the coil box). 

Thanks Chris. This is the first time I have gotten a sensible answer to a question.

[Terry Bond]

Here is a good diagram showing the basics on am early car not equipped with a starter of generator. Doesn't get much simpler. 

[Pete O]

The coils are always hot from that ninth terminal feeding the common bus under the coils, and the commutator is just a rotating ground.   Each coil has a set of points on top that are operated electro-magneticly.  When each coil is sequentially grounded by the rotating commutator, the juice already in that coil begins to flow to ground, and the current sets up the magnetic field in the primary winding, and that magnetic field also causes an electro-magnet to pull open the points which breaks the circuit,  inducing a high voltage in the secondary winding from the collapsing magnetic field, and directly off the the spark plug that high voltage goes. The collapsed magnetic field turns off the electro-magnet so the points on the coil close, which sets the whole  cycle in motion again.  You can get a few sparks each time the commutator grounds the coil, but the first one is strongest (because the coil has had more soak time for that first spark) and most critical for proper spark timing.