I have been researching and have not found a clear answer.
Looked at youtube until my eyes are crossed.
On a distributor with points, does the coil fire when the points are open or closed?
It seems that when I work on the T, everything I know about cars goes out the window.
The coil fires when the points open.
When the points are closed, current flows through the primary and builds up a magnetic field in the primary windings of the coil. When the points open, the magnetic field collapses, inducing a (much higher) voltage in the much more numerous secondary windings of the coil.
As soon as the circuit is broken from closed to open.
Now I'll complicate things a bit.
Atwater Kent marketed a distributor for the T that could utilize only ONE original Ford coil. And use it as a buzz coil. So of course you timed it for the points closing. You could also time it for a "conventional" point ignition using a non T coil
Just a bit of trivia!!!
Just double checking.
To time the rotor/distributor to the coil. The rotor should be lineup with the distributor on the up side the cam lobe. So the coil will fire and make the complete jump all the way to the spark plug.
With a regular coil you are timing to the engine not the coil. You want to set the timing to where the points are just about to open just past top dead center with the spark lever all the way up.
you can use an ohm meter-- the plug fires at the exact spot the points start to open at the beginning of the cam lobe on the distributor done like Mark says.
You can also use a light bulb (6 or 12 volt) with a couple leads attached. Connect one lead to ground and the other to the points terminal. Position crank to where you want # 1 to fire. Rotate dist till light just turns on or off.
Some were made and called a "Trouble Shooting Light." Can post a pic later. Handy to have in tool box.
How about all you "experts" checking out the operation of the Bosch distributor setup Type 600-M, that is a Bosch distributor setup using one Ford coil and powered from the Model T magneto. This fires when the points close.
I should have added that the system described is the common clip on Texas T type. The 600-M I am not familiar with. All so that the gear mesh should put the end of the rotor as close as possible to one point on the cap. The 600-M sounds like what Les was describing. The Texas T type rotates backward so the fly weights do not work. You must use the column lever. Another type rotates in the direction designed for so the advance does work. Warming up! time to get outside.
Steve, you are putting a lot of miles on your T, even if you do not drive it very much.
I set the engine with #1 piston on top with the compression stroke and move it just a little farther to about 1/16 to 1/8 inch down.
Then I install the distributor with the rotor pointing half way between the driver's side and the front of the car or about 45 degrees between the two positions.
The I adjust the spark rod so that the distributor connection is pointed straight back when the spark lever is positioned about 1/4th the way down from the top.
Then I position the distributor so the cap clips are horizontal with the radiator and the capacitor is on the back side, away from the fan.
Then I hook a wire and a ground to the removed spark plug, turn the key to Bat and note if the points are closed.
Then loosen the 10 mm nut on the distributor collar and turn the distributor just a little until the points are open, which should cause the plug to fire.
If your distributor rotor turns counter-clock-wise, it will not have a toggle in the spark rod connection, the turn should be clockwise to open the points.
If your distributor setup is older and the spark rod is separated by a toggle, then the distributor rotor turns clockwise and the distributor should be turned counter-clockwise to open the points.
This setting can also be done with a test light.
Once it is done the 10 mm nut can be tightened again on the distributor collar.
Most of the distributors still have weights in them that perform a centrifugal advance when speed is increased, so the spark rod does not need to be pulled more than halfway down for good operations.
That is the way I do it on the Texas T distributor as well. Works every time.
Tom, I first used that method in the early 1960 era on Morris Minors and MG Midgets, etc.
It worked fine for those cars,
Just to follow up.
It seems that when I reset the distributor, I did it off by one tooth.
I havenít fired it up just yet. Hope to tonight or this weekend.
I am feeling better about fixing my own screw ups. Before I take the first trip around the block. I am trying to make sure things are in order mainly the brakes and I can start it a few times in a row.