The Ford Barn

37 Coupe · 03-22-2019, 02:57 PM

I have an old Bosch coil on my Model a '31 that I know works so I planned on reusing it.Today I finally got around to reinstalling the popout switch and new wiring.Problem is on double checking my coil ,wiring schematic and Les Andrews book I notice the coil does not show which post is positive and negative,no + or - nothing. So should I go ahead and buy a coil that is probably going to be China made or this: does it matter which post or terminal I declare positive if I put correct connections on one side and correct on opposite side? Or like I said by a new coil? I also installed the NuRex temperature gauge on the bottom of the gauge panel with the mounting fixture that fits in two bottom holes and gauge is loose in the bracket.What needs to be done tape gauge body to make a fit? Just seems like evry step is an issue nothing ever easy.

100IH · 03-22-2019, 03:28 PM

Even the original coils usually don't have marking. Simple way around is get the ignition polarity indicator tool that everyone sells. Start the engine, look at the light and you have the answer.

denniskliesen · 03-22-2019, 03:44 PM

This is what 100IH is talking about. Read page 390 in the Service Bulletins. Ford changed the wires which placed the ammeter in the ignition circuit. Just to not confuse the Nu Rex polarity tester takes the guess work out of it. You can also hold the tip of a pencil between the spark plug wire and the sparkplug to see which side of the pencil the spark occurs.

Railcarmover · 03-22-2019, 05:40 PM

Bosch? good coil,if it has a number 15 on one of the tabs thats the hot side.

Badpuppy · 03-22-2019, 06:35 PM

Quote:

Originally Posted by Railcarmover

Bosch? good coil,if it has a number 15 on one of the tabs thats the hot side.

How do you define "hot" - positive or negative?

Um, Dennis, pencils are SHOCKINGLY cheaper!

zzlegend · 03-22-2019, 06:55 PM

Sponsored Links (Register now to hide all advertisements)

It will run either way hooked up. But use the tool,,,,it wont lie.
In my opinion, pencils suck. Dennis has it right. I have 2 of those in my tool boxes'
Just remember,,,,,you can lead a horse to water,,,,,but a pencil must be lead,,,,,,

Charlie Stephens · 03-22-2019, 07:00 PM

Quote:

Originally Posted by zzlegend

It will run either way hooked up. But use the tool,,,,it wont lie.
In my opinion, pencils suck. Dennis has it right. I have 2 of those in my tool boxes'
Just remember,,,,,you can lead a horse to water,,,,,but a pencil must be lead,,,,,,

I want to add to your comment: It will run if connected the wrong way, just not as good.

Charlie Stephens

noboD · 03-22-2019, 07:02 PM

If it's Bosch it was probably stolen from a VW. And like Railcarmover says 15 goes to the points. With a generator electricity moves from + to - to get to ground which the points are just that.

37 Coupe · 03-22-2019, 07:04 PM

Quote:

Originally Posted by noboD

If it's Bosch it was probably stolen from a VW. And like Railcarmover says 15 goes to the points. With a generator electricity moves from + to - to get to ground which the points are just that.

It is marked American Bosch.

zzlegend · 03-22-2019, 07:09 PM

Quote:

Originally Posted by Charlie Stephens

I want to add to your comment: It will run if connected the wrong way, just not as good.

Charlie Stephens

Yes Charlie. I should have stated that. Thanks.
As for those Bosch coils, i am running two of those on my roadsters. Great coils.

daveymc29 · 03-22-2019, 07:33 PM

You can lead a horse to drink but you can't make him water?

zzlegend · 03-22-2019, 07:43 PM

Quote:

Originally Posted by daveymc29

you can lead a horse to drink but you can't make him water?

:d:d:d:d:d:d:d:d

Tom Endy · 03-22-2019, 09:34 PM

The pencil trick has been around for ages. High school auto shop teachers loved to demonstrate this to the class, then hand the pencil to the class comedian and have him try it.

Years ago when the tool came on the market I bought one and one day at a club event we checked about 20 cars and found about half were backwards. The owners hadn't noticed the difference.

Tom Endy

Railcarmover · 03-22-2019, 11:10 PM

the best inverted 12v coil known to man..see the 15? thats where the hot wire goes,other side goes to the points..

johnbuckley · 03-23-2019, 04:48 AM

Quote:

Originally Posted by Tom Endy

Years ago when the tool came on the market I bought one and one day at a club event we checked about 20 cars and found about half were backwards. The owners hadn't noticed the difference.
Tom Endy

Out of interest Tom ,Did they notice any improvement once connected correctly?

Bruce of MN · 03-23-2019, 05:15 AM

Pencil details:

http://www.chicagolandmgclub.com/tec...neral/574.html

Although, if the MG boys are referring to Lucas, caveat emptor!!

Railcarmover · 03-23-2019, 09:41 AM

Quote:

Originally Posted by Bruce of MN

Pencil details:

http://www.chicagolandmgclub.com/tec...neral/574.html

Although, if the MG boys are referring to Lucas, caveat emptor!!

Lucas,the Prince of Darkness..had a Triumph Trophy,at night you could light a smoke off the zener diode.On the other hand,German Bosch makes superior components,if youre not into fine point their coil cant be beat,was engineered to run inverted too..

Dick Steinkamp · 03-23-2019, 10:11 AM

Posted in error. My bad.

37 Coupe · 03-23-2019, 10:13 AM

Quote:

Originally Posted by Railcarmover

the best inverted 12v coil known to man..see the 15? thats where the hot wire goes,other side goes to the points..

I didn't realize that you meant a much newer coil for the #15.This is the American Bosch coil I already had on the firewall and it did run on this. I running new wires and just questioned the previous hookup.

jrelliott · 03-23-2019, 10:38 AM

Electrons move from - to +. Electricity does not flow only electrons. Voltage is the force that drives the electrons. Amp meters measure the amount of electrons that flow past a point.

03-22-2019, 03:28 PM	#2
100IH Senior Member Join Date: Dec 2011 Location: SW Idaho Posts: 970	Re: Coil + or - Even the original coils usually don't have marking. Simple way around is get the ignition polarity indicator tool that everyone sells. Start the engine, look at the light and you have the answer.

03-22-2019, 05:40 PM	#4
Railcarmover BANNED Join Date: Apr 2017 Location: Sacramento Posts: 1,262	Re: Coil + or - Bosch? good coil,if it has a number 15 on one of the tabs thats the hot side.

03-22-2019, 06:55 PM	#6
zzlegend Senior Member Join Date: May 2010 Location: Reseda, Calif. Posts: 2,188	Re: Coil + or - Sponsored Links (Register now to hide all advertisements) It will run either way hooked up. But use the tool,,,,it wont lie. In my opinion, pencils suck. Dennis has it right. I have 2 of those in my tool boxes' Just remember,,,,,you can lead a horse to water,,,,,but a pencil must be lead,,,,,,

03-22-2019, 07:02 PM	#8
noboD Senior Member Join Date: May 2010 Posts: 319	Re: Coil + or - If it's Bosch it was probably stolen from a VW. And like Railcarmover says 15 goes to the points. With a generator electricity moves from + to - to get to ground which the points are just that.

03-22-2019, 07:33 PM	#11
daveymc29 Senior Member Join Date: Sep 2010 Location: Danville, CA Posts: 1,554	Re: Coil + or - You can lead a horse to drink but you can't make him water?

03-22-2019, 02:57 PM	#1
37 Coupe Senior Member Join Date: May 2010 Posts: 1,835	Coil + or - I have an old Bosch coil on my Model a '31 that I know works so I planned on reusing it.Today I finally got around to reinstalling the popout switch and new wiring.Problem is on double checking my coil ,wiring schematic and Les Andrews book I notice the coil does not show which post is positive and negative,no + or - nothing. So should I go ahead and buy a coil that is probably going to be China made or this: does it matter which post or terminal I declare positive if I put correct connections on one side and correct on opposite side? Or like I said by a new coil? I also installed the NuRex temperature gauge on the bottom of the gauge panel with the mounting fixture that fits in two bottom holes and gauge is loose in the bracket.What needs to be done tape gauge body to make a fit? Just seems like evry step is an issue nothing ever easy. __________________ "Never complain,never explain"... Henry Ford II

03-22-2019, 09:34 PM	#13
Tom Endy Senior Member Join Date: May 2010 Location: Southern California Posts: 3,131	Re: Coil + or - The pencil trick has been around for ages. High school auto shop teachers loved to demonstrate this to the class, then hand the pencil to the class comedian and have him try it. Years ago when the tool came on the market I bought one and one day at a club event we checked about 20 cars and found about half were backwards. The owners hadn't noticed the difference. Tom Endy

03-22-2019, 11:10 PM	#14
Railcarmover BANNED Join Date: Apr 2017 Location: Sacramento Posts: 1,262	Re: Coil + or - the best inverted 12v coil known to man..see the 15? thats where the hot wire goes,other side goes to the points..

03-23-2019, 05:15 AM	#16
Bruce of MN Senior Member Join Date: May 2010 Location: VA Posts: 1,410	Re: Coil + or - Pencil details: http://www.chicagolandmgclub.com/tec...neral/574.html Although, if the MG boys are referring to Lucas, caveat emptor!!

03-23-2019, 10:11 AM	#18
Dick Steinkamp Senior Member Join Date: Apr 2016 Location: Bellingham, WA Posts: 1,163	Re: Coil + or - Posted in error. My bad. __________________ All steel from pedal to wheel Last edited by Dick Steinkamp; 03-23-2019 at 10:20 AM.

03-23-2019, 10:38 AM	#20
jrelliott Senior Member Join Date: May 2010 Location: Pine, AZ Posts: 794	Re: Coil + or - Electrons move from - to +. Electricity does not flow only electrons. Voltage is the force that drives the electrons. Amp meters measure the amount of electrons that flow past a point.