The Ford Barn

32forddump · 08-14-2020, 07:10 PM

Is it normal to see the ammeter discharge when the points close on the Model T with a distributor? It seems very perplexing

redmodelt · 08-14-2020, 11:03 PM

Yes would be normal. You would see the same thing on most any car with points, it's just like closing a switch.

rotorwrench · 08-15-2020, 08:46 AM

When the points close, the coil draws current to build the magnetic field and it does this until the points open again. Its normal to see the amp meter fluctuate during the start phase until the engine fires up and rpm builds. At that point the breaker is opening and closing too fast for the amp meter to keep up plus the generator comes on line so it settles back down to more of a steady state.

CharlieB · 08-16-2020, 09:04 AM

It's a dead short so yes.

rotorwrench · 08-16-2020, 10:25 AM

A dead short is a circuit with no load but the conductor wire. A dead short would burn the wire or blow the fuse if there is one. An energized coil is an electromagnet until the points open back up.

32forddump · 08-21-2020, 10:04 AM

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Thanks for all your explanations. We had the unlucky occurrence of searching for a short and realized it was the closed points.

Aarongriffey · 09-01-2020, 10:53 PM

Back in the day when guys would sit with their girlfriends by the lake to watch submarine races they’d turn the ignition switch on and jab the starter button until the ammeter set straight up in the middle indicating the points were open.
Then they could turn the radio on and sit and listen to it without the ignition killing the battery.
That was before cars had an accessory position on the ignition switch.
You can also check to see if your stop lights are working from the driver’s seat.
When you push the brake pedal the ammeter should show about 2 or 3 amps discharge.

08-14-2020, 07:10 PM	#1
32forddump Senior Member Join Date: Jan 2012 Location: Ashby, Mass Posts: 452	model T with distributor Is it normal to see the ammeter discharge when the points close on the Model T with a distributor? It seems very perplexing __________________ I know I can, I know I can http://www.flickr.com/photos/waltsprojects/

08-14-2020, 11:03 PM	#2
redmodelt Senior Member Join Date: May 2010 Location: Portland OR Posts: 6,340	Re: model T with distributor Yes would be normal. You would see the same thing on most any car with points, it's just like closing a switch. __________________ I know the voices aren't real but damn they have some good ideas!

08-15-2020, 08:46 AM	#3
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,426	Re: model T with distributor When the points close, the coil draws current to build the magnetic field and it does this until the points open again. Its normal to see the amp meter fluctuate during the start phase until the engine fires up and rpm builds. At that point the breaker is opening and closing too fast for the amp meter to keep up plus the generator comes on line so it settles back down to more of a steady state.

08-16-2020, 09:04 AM	#4
CharlieB Senior Member Join Date: Sep 2010 Location: Toms River N.J. Posts: 515	Re: model T with distributor It's a dead short so yes.

08-16-2020, 10:25 AM	#5
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,426	Re: model T with distributor A dead short is a circuit with no load but the conductor wire. A dead short would burn the wire or blow the fuse if there is one. An energized coil is an electromagnet until the points open back up.

08-21-2020, 10:04 AM	#6
32forddump Senior Member Join Date: Jan 2012 Location: Ashby, Mass Posts: 452	Re: model T with distributor Sponsored Links (Register now to hide all advertisements) Thanks for all your explanations. We had the unlucky occurrence of searching for a short and realized it was the closed points. __________________ I know I can, I know I can http://www.flickr.com/photos/waltsprojects/

09-01-2020, 10:53 PM	#7
Aarongriffey Senior Member Join Date: Feb 2020 Location: Hayward,CA Posts: 513	Re: model T with distributor Back in the day when guys would sit with their girlfriends by the lake to watch submarine races they’d turn the ignition switch on and jab the starter button until the ammeter set straight up in the middle indicating the points were open. Then they could turn the radio on and sit and listen to it without the ignition killing the battery. That was before cars had an accessory position on the ignition switch. You can also check to see if your stop lights are working from the driver’s seat. When you push the brake pedal the ammeter should show about 2 or 3 amps discharge.