The Ford Barn

xmarine · 04-22-2013, 10:24 PM

With the key in the off position is the coil hot on both sides?

Jim/GA · 04-22-2013, 10:38 PM

With stock Model A wiring, yes.

Mike V. Florida · 04-22-2013, 10:53 PM

ford3 · 04-23-2013, 11:24 AM

the way i see it if it is your going to have a dead battery soon, and if some one wants to steal the car all they would have to do is push start it

MrTube · 04-23-2013, 11:30 AM

Quote:

Originally Posted by ford3

the way i see it if it is your going to have a dead battery soon, and if some one wants to steal the car all they would have to do is push start it

Hot both sides = no current being draw through coil because points are open or key is in the off position.

No dead battery and no car being stolen.

Tom Endy · 04-23-2013, 11:57 AM

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A Model A as delivered by Ford has power at all times sitting on both primary connections to the coil, both of the half wing nuts on the firewall terminal box, both connections to the ammeter, and on the connection to the generator cut-out. Power is also on both connections to the ahooguh horn. The ignition key has power sitting on one connection and completes the circuit to the ignition points when switched on.

This is why it is a good idea to install a fuse holder on top of the starter. Remove the fuse when securing the car for the day and it will remove power from all these locations.

Tom Endy

Willie Krash · 04-23-2013, 12:06 PM

Ford did many things "unconventional."
I used to get people in the shop that replaced starter relay/solenoids with later style "typical ones." That is the push button energizes the relay windings and pulls down the contactor.
Ford tied the windings to one of the big posts marked battery, to energize the relay you grounded the winding thru' the push button.

In charging systems he used B circuits almost exclusively, he deviated rarely.
Delco almost always used A circuits. Dodge used both!

MrTube · 04-23-2013, 12:07 PM

Quote:

Originally Posted by Willie Krash

Ford did many things "unconventional."
I used to get people in the shop that replaced starter relay/solenoids with later style "typical ones." That is the push button energizes the relay windings and pulls down the contactor.
Ford tied the windings to one of the big posts marked battery, to energize the relay you grounded the winding thru' the push button.

In charging systems he used B circuits almost exclusively, he deviated rarely.
Delco almost always used A circuits. Dodge used both!

What are A and B circuits?

Mitch//pa · 04-23-2013, 12:38 PM

Quote:

Originally Posted by MrTube

What are A and B circuits?

A circuit field tied to voltage source inside generator and regulator
switches resistance in and out of circuit to ground to control field
current. Grounding field terminal produced full output.

B circuit field is grounded inside generator and regulator switches
resistance between field terminal and voltage source to control field
current.

Phil · 04-23-2013, 09:00 PM

Ok just to clarify, some of the answers are a bit confusing. The black side of the coil is hot at all times. You will get a voltage reading to ground on the red side of the coil with switch off and points open. This is feeding through the coil. If you disconnect the red wire from the coil, the coil terminal will have voltage to ground the red wire will not. The red wire furnishes a ground to the coil via the key switch when the points close. This is what causes the coil to fire each time the points close.

04-22-2013, 10:24 PM	#1
xmarine Senior Member Join Date: Jun 2010 Location: Arkansas Posts: 125	A simple wiring question! With the key in the off position is the coil hot on both sides?

04-22-2013, 10:38 PM	#2
Jim/GA Senior Member Join Date: May 2010 Location: Young Harris, GA Posts: 1,821	Re: A simple wiring question! With stock Model A wiring, yes. __________________ Jim Cannon Former MAFCA Technical Director "Have a Model A day!"

04-22-2013, 10:53 PM	#3
Mike V. Florida Senior Member Join Date: May 2010 Location: South Florida Posts: 14,054	Re: A simple wiring question! __________________ What's right about America is that although we have a mess of problems, we have great capacity - intellect and resources - to do some thing about them. - Henry Ford II

04-23-2013, 11:24 AM	#4
ford3 Senior Member Join Date: Oct 2012 Location: oroville calif. Posts: 1,453	Re: A simple wiring question! the way i see it if it is your going to have a dead battery soon, and if some one wants to steal the car all they would have to do is push start it

04-23-2013, 11:57 AM	#6
Tom Endy Senior Member Join Date: May 2010 Location: Southern California Posts: 3,131	Re: A simple wiring question! Sponsored Links (Register now to hide all advertisements) A Model A as delivered by Ford has power at all times sitting on both primary connections to the coil, both of the half wing nuts on the firewall terminal box, both connections to the ammeter, and on the connection to the generator cut-out. Power is also on both connections to the ahooguh horn. The ignition key has power sitting on one connection and completes the circuit to the ignition points when switched on. This is why it is a good idea to install a fuse holder on top of the starter. Remove the fuse when securing the car for the day and it will remove power from all these locations. Tom Endy

04-23-2013, 12:06 PM	#7
Willie Krash Senior Member Join Date: Jan 2012 Location: Phoenix, Oregon Posts: 661	Re: A simple wiring question! Ford did many things "unconventional." I used to get people in the shop that replaced starter relay/solenoids with later style "typical ones." That is the push button energizes the relay windings and pulls down the contactor. Ford tied the windings to one of the big posts marked battery, to energize the relay you grounded the winding thru' the push button. In charging systems he used B circuits almost exclusively, he deviated rarely. Delco almost always used A circuits. Dodge used both! __________________ Mike Stitt "A business that make nothing but money is a poor business." -Henry Ford

04-23-2013, 09:00 PM	#10
Phil Senior Member Join Date: May 2010 Location: Bethany, Ok Posts: 382	Re: A simple wiring question! Ok just to clarify, some of the answers are a bit confusing. The black side of the coil is hot at all times. You will get a voltage reading to ground on the red side of the coil with switch off and points open. This is feeding through the coil. If you disconnect the red wire from the coil, the coil terminal will have voltage to ground the red wire will not. The red wire furnishes a ground to the coil via the key switch when the points close. This is what causes the coil to fire each time the points close.