coil positive ground

[CP]

Tried to search to no success. Replacing an original 6v positive ground coil with a new 6v coil. Old coil is for dummies like me. One terminal says battery and the other says distributor. The new coil says "+" and "-". I thought the "+" would go to the battery even though + is ground. It runs great now, however, I believe it may need to be switched? Any damage done from hooking up backwards? I do not understand electricity at all, my apologies. Thank You, CP

Truck was running like it was out of gas yet plenty of gas (only when at running temp). Changed the coil and it now has excellent throttle response even when warmed up. Thoughts appreciated.

[JSeery]

Need to keep the polarity straight. A coil will run connected backwards, but not correctly (as designed). In your case the (+) terminal should be ground (connect to the distributor and the (-) terminal should be power (connect to the battery through the ballast resistor and ignition switch).

"There is a way to check directly which way the current is flowing in the high tension circuit. Disconnect a spark wire from a spark plug (or the coil wire from the distributor cap). Hold this HT wire near a grounding point (or near the connector end of a spark plug), and position the tip of a graphite pencil in between. When you crank the engine (no need to start or run) you can observe the resulting spark jump between wire and pencil, and between pencil and ground (or spark plug). A flare (hard to see) toward the plug (or ground) shows correct polarity while a flare toward the coil shows reversed polarity. If the flare goes toward the coil, just switch the primary wires on the coil and make note of the connections for future reference."

"Can't see the flare? Not sure yet? You can also check spark polarity using an analog (moving needle) volt meter. Hook up a voltmeter with the negative lead to the plug terminal and the positive lead to the block. Set the meter on the highest volt range. Crank the engine over (no need to start it), and you should see an upward swing of the voltmeter needle (don't be concerned with taking a reading). If the needle swings down off the scale, your coil is hooked up wrong. To correct it reverse coil primary leads. Do not worry about the coil markings, but make note of them for future reference."

[Paul Bennett]

From http://modelabasics.com/Ignition.htm#polarity


How The Coil Works
The coil itself does not care which way it is hooked up, it will be just as efficient either way. On the other hand the spark plugs do care. They prefer the center electrode to be negative and the end electrode to be positive. The reason is electrons like to jump from a cold surface to a hot surface and the center electrode of a spark plug is hotter than the end electrode. By correctly establishing the coil’s polarity the voltage required to jump the spark plug gap is 15 to 30 percent stronger which may or may not be evident on the performance of your ‘A’ depending on the condition of the ignition components. Oddly enough the large amount of voltage created by the coil is not affected, positively or negatively, by the mere 6 volts (or 12) of the battery. Therefore; positive ground or negative ground of the battery is not relevant.

Tom Wesenberg Tip:
"To check coil polarity hold a pencil lead in the spark path with the plug wire about a third of an inch away from the distributor terminal. You’ll see a FLARE on one side of the pencil lead and this flare should be on the spark plug side of the lead." Tom suggests to hold the pencil in the middle or even slide the pencil into a plastic tube to avoid an electrical shock.
If the flare is on the plug wire side. Switch the two wires on the coil.

[rotorwrench]

They also make a little polarity tester that makes life easy.
http://www.macsautoparts.com/early_v...it-381474.html

[BUBBAS IGNITION]

Some bad info here !!! Once a coil has been ran in a given polarity , it shouldnt be reversed.

The steel laminations in the coil will retain some magnetism and interfere when polarity is reversed. Incorrect polarity can loose 80% of its power when wired incorrectly...

[Ronnie]

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Originally Posted by BUBBAS IGNITION

Some bad info here !!! Once a coil has been ran in a given polarity , it shouldnt be reversed.

The steel laminations in the coil will retain some magnetism and interfere when polarity is reversed. Incorrect polarity can loose 80% of its power when wired incorrectly...

De magnetize it.
Can be done is it worth it probably not just don't run it the other way.Any machine shop with a magna flux system and de mag coil can do that but Bubbas info is a good one to keep in mind as he is a fountain of knowledge in the ignition world.

R

[BillM]

The reason is electrons like to jump from a cold surface to a hot surface

I think that is backwards:

As electrons go, they love to jump away from a hot surface and fly toward a colder surface,

See :http://mgaguru.com/mgtech/ignition/ig104.htm

[BillM]

The steel laminations in the coil will retain some magnetism

The laminations are made to be easily magnetized (and demagnetized) so I really doubt that any residual magnetism would be permanent.

[rotorwrench]

The coils are made to be an inductor same as used in AC circuits. They use the breaker points to make them operate as an inductor under pulsating half wave DC or simulated AC. They do build a magnetic field but they don't hold it. An AC coil is used to demagnitise parts.

The two coils inside (primary and secondary) are connected together at one end and not the other. It's this connection that makes them polarity sensitive.

[flatheadmurre]

Residual magnetism (Frem) is going to be a factor in any pulse transformer.
Depending on steel in the lamination it can go so high it will make the transformer saturate earlier then intended.
An ignition coil wil be charged and depleted with DC only and when the excitation stops the flux will not go back to zero, you have remanence flux (residual magnertism) left in the coil.
This is the same thing that makes our generators start up and work.
Wow...im as boring as they come... never going to be a good teacher...all will fall asleep

[BUBBAS IGNITION]

Originally Posted by flatheadmurre

residual magnetism (frem) is going to be a factor in any pulse transformer.
Depending on steel in the lamination it can go so high it will make the transformer saturate earlier then intended.
An ignition coil wil be charged and depleted with dc only and when the excitation stops the flux will not go back to zero, you have remanence flux (residual magnertism) left in the coil.
This is the same thing that makes our generators start up and work.
Wow...im as boring as they come... Never going to be a good teacher...all will fall asleep

i agree with that theory!!

[Jack E/NJ]

>>>This is the same thing that makes our generators start up and work.>>>

So I guess that means you can polarize the coil either way by reversing the connections just like CP observed? Jack E/NJ

[rotorwrench]

Most old ignition coils have the high tension tower and the two smaller terminals for Bat and Dist. The manufacturers quit identifying them that way around the time that 12-volt negative ground systems became common. They generally all have + & - now. Now which terminal has the primary and secondary leads inside connected to it? You would think it would be the positive or"+" terminal but it might be and it might not be. This is why you need to have a polarity test method or tester.

Residual magnetism in the core will change polarity as soon as you connect the terminals of the coil the other way round just like it will in a field coil on a generator but it won't change where the primary and secondary end leads are connected together inside the coil.

[Ronnie]

http://www.aa1car.com/library/ignition_coils.htm
http://mgaguru.com/mgtech/ignition/ig104.htm

R

[BUBBAS IGNITION]

Originally Posted by Jack E/NJ

>>>This is the same thing that makes our generators start up and work.>>>

So I guess that means you can polarize the coil either way by reversing the connections just like CP observed? Jack E/NJ

A lot of them get switched and dont run very well. Once the fields set in a ignition coil they dont easily become reversed etc...

[Brian]

I'm a bit confused now [not hard to confuse me!]- once the fields are set in an ignition coil, they don't easily become reversed. If I were to initially check the polarity of a brand new coil with the above pencil test, and found it was reversed, wouldn't that immediately have 'set' the fields within the coil, meaning that, even if I then reversed the wiring to correct the polarity issue, there would be the potential [no pun intended] , for the coil to not operate as it should?

[flatheadmurre]

It´s a bit more at work when putting in a coil the wrong way...
So how does the coil work when all is well ?
Points closed current running through primary winding building up magnetic field.
points open no current running through primary winding magnetic field collapse disharging through secondary winding.
If we hook it up backwards we get a new problem...when the points open the primary will be in series with the secondary...so one effect can be overheating since primary will now have current passing through it all the time.
So what will the voltage at the junction between primary/secondary be now...are we exceeding the normal voltage in the primary circuit ?
As always more to it then at first glance...

[rotorwrench]

An analogy that is used a lot on ignition coils is the reference to ringing a bell. A bell makes resonant sound waves after it is struck. The striker on an ignition coil is the opening of the circuit breaker points. When the points open it causes the rapid collapse of the magnetic field which makes a resonance between the primary and secondary coils (inductance). This is where the voltage gets stepped up. The condenser holds that little charge that insures a good resonance to make induction more efficient in the split second that it all happens. If you reverse polarity, the electron flow has a different pathway back into the system and squelches the resonance some. The bell don't ring as well if it doesn't get struck as hard and it craps out sooner. It still functions but not as well as it could.

I don't know if this will illustrate what happens better for folks or not but the best way to actually see it is on an oscilloscope while the system is in operation.

[CP]

I appreciate all the responses. I know one thing, I will never install the coil backwards again. Thank You so much.

[BUBBAS IGNITION]

Originally Posted by Brian

I'm a bit confused now [not hard to confuse me!]- once the fields are set in an ignition coil, they don't easily become reversed. If I were to initially check the polarity of a brand new coil with the above pencil test, and found it was reversed, wouldn't that immediately have 'set' the fields within the coil, meaning that, even if I then reversed the wiring to correct the polarity issue, there would be the potential [no pun intended] , for the coil to not operate as it should?

Thats true.....if ran for a short time it might not be as bad as if it had ran for years etc.
I check coils for out put on a allen machine , anytime is have one with low out put i look at the polarity usually i have it wired backwards on my tester. Reverse the leads and the output is fine......