I just bought a coil box in the 17 style that the guy told me was wired for an electric start. What does that mean, I'm a little confused?
Me too. The coil box has nothing to do with the starter. It's wired to send a current to the coils from either a battery (BAT) or a magneto (MAG) or not at all (OFF). You can check the wiring yourself. There should be one wire from the BAT terminal to one side of the switch, and a wire from the MAG terminal to the other, and a wire from the switch to the strip in the bottom of the box. No other wires needed.
Ok I will investigate that. That makes more sense now. How do you tie the battery side into the battery? Where does the wire go from the coil box towards the battery? Thank you.
If your car is a 1917, there was no battery from the factory. So, if you do install one you are on your own how to route the cable. For running the coils I would use a No 12 wire, minimum. If you are also going to have a starter motor, you will need much heavier wires. Search for the many posts on starter wiring for more info. Don't forget to make a good ground to the frame for your battery.
I respectfully suggest that you really do not need a heavy wire for the coil box. The entire box only draws 1.3 amps when a coil is buzzing and half that (.65A) when the engine is running hence even #18 is heavy enough to get from the coil box to a battery under the seat on in a running board box. For convenience anything heavier will of course work OK but not at all necessary.
Pay close attention to the photo (coilbox facing the rear of the car) and explanation Steve Jelf contributed.
Here is a photo of the coilbox facing the front of the car.
Notice the two terminals at the bottom of the coilbox marked B and M. The magneto output is connected to the M terminal. As Tom pointed out a 1917 Model T would not have had any wire connected to the B coilbox terminal from the factory, but many owners connected a set of dry cell batteries to the B terminal and this was used to facilitate hand crank starting.
From Steve's photo you can see how the switch connected either the B or M terminal to the center position of the switch and hence the power strip in the bottom of the coilbox.
Ron the Coilman
That's what I needed! Thanks