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Positive Ground Application - Coil Polarity Hookup

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A

Andrew1

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I was upgrading to a Lucas sport coil to help increase my sparkplug gaps to help cold weather starting on my Positive Ground BJ8.

Upon removing the old generic coil, I was surprised to notice that the last installer had the lucar distributor points lead running from the Negative (-) side of the coil to the Distributor, and similarly the the Tach lead was connected to the (-) Negative side of the coil.

The ignition switch terminal was running to the (+) side of the coil. I did not install the last coil, but it would seem to me to be backward?

The car works fine when I attach them either way?

Can someone set me straigh on the correct (+/-) coil hook-up for the Tach/Points leads Vs Ignition Switch lead for a POSITIVE ground application.

- Andrew 1 -
 
JamesWilson

JamesWilson

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Hendrix Wire Wheel has a guide to polarity change for the Healey. The neg wire should go to the distributor {edited to add} for a negative ground car.

Hope this helps....
 
Keoke

Keoke

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Hi Andrew, If your car is Positive ground Then the positive terminal of the coil is connected to the Dizzy Lucar connector and the Negative terminal is routed back to the Ignition SW.Yes the car will run in either configuration of the coil,however, when hooked up incorrectly you add about 25% more stress to the high tension cables.FWIW--Keoke
 
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A

Andrew1

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Keoke:

Thank you for being clear, so I have the Polarity straight.

Now, can you help me understand the third wire (white-ish) hooked up to the positive side of the coil along with lead for the points? What's that for?

Is it correct now that the one wire attached to the negative side of the coil is for both the switch and the tachometer connected in series?

- Andrew 1 -
 
dklawson

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David, that's a nice link you posted. I'm a bit curious about something they show at that site and I hope that Dave R. or Keoke will take a minute to look at the link and comment on it. In addition to the pencil test the author shows a volt-meter method of checking coil polarity. I'm not sure I understand how the author is safely making that connection and not burning up his meter.

"Now, can you help me understand the third wire (white-ish) hooked up to the positive side of the coil along with lead for the points? What's that for?" If I understand Andrew's question, and this car is positive ground, is he talking about the series wires for an RVI tach connected between the dizzy and coil?
 
GregW

GregW

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[ QUOTE ]

Now, can you help me understand the third wire (white-ish) hooked up to the positive side of the coil along with lead for the points? What's that for?

[/ QUOTE ]
If by white-ish meaning white/black, that would be the wire that goes back the battery cut-off switch in the trunk. Used as an anti-theft device.
[ QUOTE ]

Is it correct now that the one wire attached to the negative side of the coil is for both the switch and the tachometer connected in series?

[/ QUOTE ]
For a positive ground car, yes.
 
Keoke

Keoke

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HI DK,WOW! I thought I had been had when I first saw his test set up, He is just using the open circuit voltage from the coil with the Voltmeter set to measure the correct polarity of the open circuit voltage.For a Neg ground case and the meter polarity connected like wise you should see the needle go up if it goes down polarity is wrong.Hope this helps.---Keoke
 
Dave Russell

Dave Russell

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Re: Positive Ground Application - Coil Polarity Ho

[ QUOTE ]
I'm a bit curious about something they show at that site and I hope that Dave R. or Keoke will take a minute to look at the link and comment on it. In addition to the pencil test the author shows a volt-meter method of checking coil polarity. I'm not sure I understand how the author is safely making that connection and not burning up his meter.

[/ QUOTE ]
Hi Doug,
You are correct, the full spark voltage will be applied to the meter. My Simpson 260 has a 5 kv scale on it. I'm not sure if the meter's insulation would withstand the 15 kv or so from the spark. Even though he says just to observe the needle direction, & don't worry about the magnitude, the meter is still exposed to the spike voltage. They do make high voltage probes for some meters, I've got one somewhere for measuring TV picture tube voltage. Try it with your meter if you wish, I'm not curious enough to find out.

Any auto shop with an ignition scope could tell in a hurry.
D
 
dklawson

dklawson

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Re: Positive Ground Application - Coil Polarity Ho

I've blown up one meter in my past and am not interested in doing it again. I thought perhaps the author meant to loop the meter lead around the plug boot or run it along the length of the plug wire to pick up an inductive pulse or something. I may try a non-contact version of this but I certainly won't hook my meter up to the plug directly.
 
Keoke

Keoke

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Re: Positive Ground Application - Coil Polarity Ho

/ubbthreads/images/graemlins/iagree.gif DK, I would recommend that a high voltage probe like my old Eicho unit be used rather than depending on the narrow band width of a standard DC VOM to protect it.---Keoke
 
Dave Russell

Dave Russell

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Re: Positive Ground Application - Coil Polarity Ho

Hi Keoke,
I have one of those meters with probe also. You must be pretty old.
D /ubbthreads/images/graemlins/grin.gif
 
Keoke

Keoke

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Re: Positive Ground Application - Coil Polarity Ho

[ QUOTE ]
Hi Keoke,
I have one of those meters with probe also. You must be pretty old.
D /ubbthreads/images/graemlins/grin.gif

[/ QUOTE ]

/ubbthreads/images/graemlins/savewave.gif
You just better watch that mouth DR!---Keoke- /ubbthreads/images/graemlins/lol.gif
 
dklawson

dklawson

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Re: Positive Ground Application - Coil Polarity Ho

Gee... I don't know what you guys are talking about.
 
Keoke

Keoke

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Re: Positive Ground Application - Coil Polarity Ho

[ QUOTE ]
Gee... I don't know what you guys are talking about.

[/ QUOTE ]

ITS Grown folks conversation not fer youngsters.---Keoke /ubbthreads/images/graemlins/grin.gif
 
D

Deleted member 3577

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Re: Positive Ground Application - Coil Polarity Ho

Have to admit I was a bit skeptical about the volt meter idea.

That's why I recommended the pencil trick. (it does work)

Does anyone have a junk meter that they may want to sacrifice, for sake of curiosity?
 
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