The Ford Barn

fundytides · 08-01-2018, 04:24 PM

I have several older 6v coils, marked bat. & dist. I don't know what they are off but do I assume that they are off neg. ground systems and therefor hook them up backwards on the Model A pos. ground

Mike V. Florida · 08-01-2018, 05:26 PM

You need to measure the resistance between the two terminals to see if they are "6" volt of "12" volt. about 1.5 ohms are 6 volt, and about 3 ohms are 12 volt. I would install with the Batt going to the positive side of the battery.

fundytides · 08-01-2018, 07:51 PM

Thanks Mike. They are 6 volt coils. So if I understand you correctly, on a Model A pos. ground system, the "Bat" term would be connected to the distributor through the ignition switch.

Tom Wesenberg · 08-01-2018, 08:35 PM

You can't know without doing the coil polarity check.
That's why it's dumb to mark them as they did, rather than with + and -.
Google "coil polarity" and read the excellent short article by Chicgoland MG club.

160B · 08-01-2018, 09:20 PM

Quote:

Originally Posted by Tom Wesenberg

You can't know without doing the coil polarity check.
That's why it's dumb to mark them as they did, rather than with + and -.
Google "coil polarity" and read the excellent short article by Chicgoland MG club.

here are two links to the referenced article by Chicgoland MG club?

http://1929modelaford.blogspot.com/2...-polarity.html

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

dumb person · 08-02-2018, 01:48 AM

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Maybe the coil maker didn't care about polarity as long as the coil was earthing through the contact breaker.

fundytides · 08-02-2018, 06:53 AM

Thanks for all the information guys. Since I don't know what car these coils are for, I'll do the polarity test once my wiring is completed. It doesn't sound like it makes much difference anyway but it will satisfy my curiosity

08-01-2018, 04:24 PM	#1
fundytides Senior Member Join Date: Feb 2013 Location: New Brunswick, Canada Posts: 480	model a coil I have several older 6v coils, marked bat. & dist. I don't know what they are off but do I assume that they are off neg. ground systems and therefor hook them up backwards on the Model A pos. ground

08-01-2018, 05:26 PM	#2
Mike V. Florida Senior Member Join Date: May 2010 Location: South Florida Posts: 14,054	Re: model a coil You need to measure the resistance between the two terminals to see if they are "6" volt of "12" volt. about 1.5 ohms are 6 volt, and about 3 ohms are 12 volt. I would install with the Batt going to the positive side of the battery. __________________ 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

08-01-2018, 07:51 PM	#3
fundytides Senior Member Join Date: Feb 2013 Location: New Brunswick, Canada Posts: 480	Re: model a coil Thanks Mike. They are 6 volt coils. So if I understand you correctly, on a Model A pos. ground system, the "Bat" term would be connected to the distributor through the ignition switch.

08-01-2018, 08:35 PM	#4
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: model a coil You can't know without doing the coil polarity check. That's why it's dumb to mark them as they did, rather than with + and -. Google "coil polarity" and read the excellent short article by Chicgoland MG club.

08-02-2018, 01:48 AM	#6
dumb person Senior Member Join Date: Apr 2011 Location: South pacific island Posts: 1,724	Re: model a coil Sponsored Links (Register now to hide all advertisements) Maybe the coil maker didn't care about polarity as long as the coil was earthing through the contact breaker. __________________ <Link> This is how we roll<Link> "I'm Convinced that no one really reads posts anymore; they just fabricate what they think the post says then ramble on about red herrings."--Bob Outcasts rules of old cars #1 Fun is imperative, mainstream is overrated #2 If they think it is impossible, prove them wrong #3 If the science says it impossible you are not being creative enough. #4 No shame in recreating something you never had #5 If it were not for the law & physics you would be unstoppable

08-02-2018, 06:53 AM	#7
fundytides Senior Member Join Date: Feb 2013 Location: New Brunswick, Canada Posts: 480	Re: model a coil Thanks for all the information guys. Since I don't know what car these coils are for, I'll do the polarity test once my wiring is completed. It doesn't sound like it makes much difference anyway but it will satisfy my curiosity