Coil wiring stock 6 volt

[Vanspeed]

I am in the process of replacing my main wiring harness in my 48 f-1 and I am almost done. Today I got my distributor to coil wire and I am confused. I bought the harness from Sacramento vintage ford. In the wiring diagram it says to hook the ringed wire from the harness to the + side of the coil, this would mean that the distributor wire goes to the - side of the coil. After reading about 6 volt positive ground systems, this seems backwards. Is the diagram correct? Any help is appreciated.

[48 coupe]

I think you are right if you have + ground that wire should go to the - post on the coil. someone will have ath real poop .HMMMMM

[Mac VP]

On a positive ground system the coil grounds thru the distributor points. So the coil should get the 6V power wire to its negative terminal and the other terminal goes to ground via the distributor points.....thus the other wire would connect from the coil "positive " terminal to the distributor.

The instructions seem to contradict that. I would talk to the harness supplier for a second opinion.

[MGG]

I would check with Ron Palmer at Sacramento Vintage Ford. He makes their harnesses and is a very friendly and helpful.

[Vanspeed]

Yeah I will call them tomorrow, I just double checked and it clearly says to hook the wire from the harness to the positive side of the coil.

[WestCoast]

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all gauges on a positive ground car has to use the positive side of the battery as the ground, unless you have changed the car from + to negative ground, the hot wire goes (negative) to the coil. the ground wire (+) goes to the dist, a wiring harness does not change that, the directions are wrong

[Vanspeed]

This is completely bone stock, no conversions. You would think somebody like Sacramento would have correct instructions.

[48 coupe]

West cost has nailed it. That is the way it is. The wiring guy isn't old enough to know those things.

[scooder]

You don't have to be old to know which way a coil is wired, just vehicle electric savy.
As above ground wire goes to the points.
Do ring Sacramento, it's just a mistake easy to make, but could be your wiring instructions are for a negative ground system.
Martin.

[Vanspeed]

Just got off the phone with Ron over at Sacramento. He told me that he has been making the harnesses like that for 15-20 years. Said he followed a original schematic. He did say that in his opinion it does not matter which way it is hooked up. He said unless it is a race car, there isn't any difference. He said I can hook it up either way. What do you guys think about his response?

[V8COOPMAN]

Let's see, who was that other lovely, charming, trustworthy person that said......"What difference does it make?" Pathetic..... in both cases! DD

[34fordy]

The engine will run either way but his way is NOT the right way--Just because he has been doing it that way for 25 years is irrelevant--It goes to prove you can not believe every thing in print--
It is never a sign of weakness to admit you are wrong--

[Vanspeed]

I am going to wire it up like you guys say. Hopefully the rest of the diagram/instructions are correct.

[V8 Bob]

Originally Posted by Vanspeed

Just got off the phone with Ron over at Sacramento. He told me that he has been making the harnesses like that for 15-20 years. Said he followed a original schematic. He did say that in his opinion it does not matter which way it is hooked up. He said unless it is a race car, there isn't any difference. He said I can hook it up either way. What do you guys think about his response?

The coil output will be about 30% less when wired with the wrong polarity. The coil always follows the system polarity, and with positive ground, the positive coil goes to the distributor, or ground.

[rotorwrench]

If you ever find a can type coil from the late 40s early 50s, they will generally be marked Dist & Bat on the terminals so it doesn't get confusing but that changed after 1956 when everything went 12-volt negative ground.

You can still get the little coil polarity testers from a lot of early parts sources but you can also use a pencil to check it. Although they will function either way, an ignition coil is only at peak effeciency when polarity is correct. You never know whether the manufacturer got the + or - in the right places either these days. Anyone who believes that polarity doesn't matter needs to get more education than what they had before a statement like that.

[zzlegend]

Originally Posted by rotorwrench

If you ever find a can type coil from the late 40s early 50s, they will generally be marked Dist & Bat on the terminals so it doesn't get confusing but that changed after 1956 when everything went 12-volt negative ground.

You can still get the little coil polarity testers from a lot of early parts sources but you can also use a pencil to check it. Although they will function either way, an ignition coil is only at peak effeciency when polarity is correct. You never know whether the manufacturer got the + or - in the right places either these days. Anyone who believes that polarity doesn't matter needs to get more education than what they had before a statement like that.

X2 on this post. I use this tool every time I change a coil. Even though it will run hooked up either way, this helps get it right. Just a thought.

http://brattons.com/product.asp?P_ID...=any&PT_ID=all

[Rand]

Not to steal this tread...but how do I test my spare coils with a simple voltmeter? Tks
Randy

[rotorwrench]

A volt meter will give you resistance readings for the primary and secondary wire coils which you can check against normal values but it can't help with actual in service conditions. When a coil gets a crack in the wire somewhere in the turns, it can work just fine when cold and then go open circuit as it gets hot and things expand. The old coil testers actually tested the coil under normal operating conditions but even those testers may not catch problems under extreme conditions of hot or cold weather.

The secondary winding can be checked across the two little terminals. The primary winding is checked from the distributor terminal to the coil tower output terminal. Now whether the negative terminal for the distributor is the proper terminal or not is up for grabs but that would be the normal procedure for a modern coil. You would have to check the manufacturers publications for the proper range of resistance for the primary and secondary coils.

Correction: primary is input (small terminals), low voltage, and secondary is output (Dist or negative terminal to coil high tension tower output), high voltage. I had them in reverse order in previous statement.

[G.M.]

Originally Posted by Rand

Not to steal this tread...but how do I test my spare coils with a simple voltmeter? Tks
Randy

You can only test to see if the windings have the correct resistance, are open or shorted. The only way to test an old Ford coil is on a coil testing machine. Almost all of these coils run good cold but the problem starts when they get hot. You have to get them up in the 200 degree range then see how far the arc jumps. It should jump 3/8 to a 1/2" when hot. A bad coil when hot puts out a small weak spark. As it gets hotter the spark gets shorter until it gets down to a small yellow ball maybe 1/16"in diameter and will hardly jump any distance. It takes 15 or 20 minutes to test a coil.
99 out of a 100 don't pass the heat test it's not worth the time to test them
just have it rebuilt. G.M.

[Ross F-1]

Originally Posted by rotorwrench

...
The secondary winding can be checked across the two little terminals.

The primary winding is checked from the distributor terminal to the coil tower output terminal. ...

I think you have those reversed...
(note that the pic below is for a modern (-) ground coil)