Petronoix III. What's the Good, Bad and Ugly of these things?

[Big_John]

Well the fact remains Big John that 1960's vintage points ignitions ran 6 volt coils not 12 volt. And is why they worked well in stock cars for many years on 12 volts.
They were a carry over from 6 volt ignitions of the 50's and before and the ballast kept them alive on 12 volts when 12 volts were the norm..
I guess 0n 12 volts the points would burn up yes??,,,,Yes,,

It's amperage that would burn up points and not voltage. The ballast resistor limits the current through the points.

Here's a basic electricity exercise for you. Take a ballast resistor (1.2 ohms) and connect one terminal to a piece of wire. Connect the wire to one terminal of a 12 volt battery. Take your voltmeter and measure the voltage at the unhooked terminal of the ballast resistor. What's the voltage? Here's a hint... it's gonna be 12 volts. Now stick a wire on an ignition coil and connect it in series with the ballast resistor. Measure the voltage at the other coil terminal and it's gonna be 12 volts again. The current that can pass through is a different story.

Ohms law. V=IR

A coil draws about 2 amps when the points are closed. That's good because you don't want more than 4 amps of current through the points. The coil primary resistance is about 1.8 ohms. (This also makes it easier to figure) and is in series with the 1.2 ohm BR. Got me so far? 1.2 + 1.8 = 3 ohms total resistance in the primary. Still with me?

V=IR Voltage = Current x resistance. You have a 2 amp draw so V= 2R You have 3 ohms (1.2 + 1.8) resistance in the primary ignition circuit. V=2 x 3.

Freaking magic ! The answer is 6 volts. This is why you measure 6 volts at the coil with a 12 volt system when it's hooked up and you have a draw.

Now, let's take a coil like they use with a 12 volt system and without a ballast resistor... Typically these are on tractors and such. The resistance is higher on the primary side. Like about 4 ohms... Do the math again.
12=I x 4 I=3 amps, still less than 4.

The problem is that most guys don't understand basic electricity and... shudder... Ohm's Law. Honestly, I've never seen a coil referred to by "voltage". I have seen some (low primary resistance) that are listed to use with a 6 volt system with no ballast resistor. Again, do the math.

BTW, coils in newer cars with electronic ignitions draw about 4 amps... The ignitions can take that type of current and the increased current gives a "hotter" spark.

Now... all this was typed off the cuff and under the influence of some good pain drugs.... So there may be some mistakes somewhere.

 

[Turboomni]

Sorry your on pain meds Big John and thanks for typing that all in for us. This is what I found from a quick search.

https://www.amazon.com/STANDARD-IGN-UC14T-Ignition-Coil/dp/B016YKNCN6#detail-bullets


Summit has complete application chart ,many pages.
1969 PLYMOUTH FURY III Standard Motor Ignition Coils UC14T

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STANDARD IGN UC14T Ignition Coil - 6 V
by STANDARD IGN
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1969 PLYMOUTH FURY III Standard Motor Ignition Coils UC14T
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Ignition Coil, OEM Replacement, T-Series, 6-Volt, Each

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Standard Motor Ignition Coils

Part Type:Ignition Coils
Application:1969 PLYMOUTH FURY III

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Universal:No

MakeLYMOUTH

Model:FURY III

Submodel:BASE

Beginning Year:1967

Ending Year:1969

Engine Type:V8

Engine Family:Mopar big block RB

Engine Size:7.2L/440

Engine VIN Code:K

Application Notes:Alternate Number

Universal:No

MakeLYMOUTH

Model:FURY III

Submodel:BASE

Beginning Year:1967

Ending Year:1969

Engine Type:V8

Engine Family:Mopar big block RB

Engine Size:7.2L/440

Engine VIN Code:L

Application Notes:Alternate Number

Universal:No

MakeLYMOUTH

Model:FURY III

Submodel:BASE

Beginning Year:1968

Ending Year:1969

Engine Type:V8

Engine Family:Mopar big block RB

Engine Size:7.2L/440

Engine VIN Code:K

Application Notes:w/ Single Points Chrysler

Universal:No

MakeLYMOUTH

Model:FURY III

Submodel:BASE

Beginning Year:1968

Ending Year:1969

Engine Type:V8

Engine Family:Mopar big block RB

Engine Size:7.2L/440

Engine VIN Code:L

Application Notes:w/ Single Points Chrysler

Universal:No

MakeLYMOUTH

Model:FURY III

Submodel:BASE

Beginning Year:1968

Ending Year:1974

Engine Type:V8

Engine Family:Mopar big block RB

Engine Size:7.2L/440

Universal:No

MakeLYMOUTH

Model:FURY III

Submodel:SPORT SUBURBAN

Beginning Year:1968

Ending Year:1969

Engine Type:V8

Engine Family:Mopar big block RB

Engine Size:7.2L/440

Engine VIN Code:K

Application Notes:Alternate Number

Universal:No

MakeLYMOUTH

Model:FURY III

Submodel:SPORT SUBURBAN

Beginning Year:1968

Ending Year:1969

Engine Type:V8

Engine Family:Mopar big block RB

Engine Size:7.2L/440

Engine VIN Code:K

Application Notes:w/ Single Points Chrysler

Universal:No

MakeLYMOUTH

Model:FURY III

Submodel:SPORT SUBURBAN

Beginning Year:1968

Ending Year:1969

Engine Type:V8

Engine Family:Mopar big block RB

Engine Size:7.2L/440

Engine VIN Code:L

Application Notes:Alternate Number

Universal:No

MakeLYMOUTH

Model:FURY III

Submodel:SPORT SUBURBAN

Beginning Year:1968

Ending Year:1969

Engine Type:V8

Engine Family:Mopar big block RB

Engine Size:7.2L/440

Engine VIN Code:L

Application Notes:w/ Single Points Chrysler

• Standard Blue Streak DIS ignition coils use pure copper windings in both bobbins to improve durability
• Standard is a global manufacturer of original equipment ignition products, complete quality control
• A full E-Lam core of silicon steel and solid brass high voltage terminals protects against corrosion.
• Fits for various make, model and yearSpecifications
• Connector Gender - Female (1)

Specifications for this item
Brand Name STANDARD IGN
Number of Items 1
Part Number S65-UC14T
UNSPSC Code 25170000

• Standard Blue Streak DIS ignition coils use pure copper windings in both bobbins to improve durability
• Standard is a global manufacturer of original equipment ignition products, complete quality control
• A full E-Lam core of silicon steel and solid brass high voltage terminals protects against corrosion.
• Fits for various make, model and yearSpecifications
• Connector Gender - Female (1)

Specifications for this item
Brand Name STANDARD IGN
Number of Items 1
Part Number S65-UC14T
UNSPSC Code 25170000

 

[James Romano]

I just hate to see anyone having a problem with a points ignition and then putting down the whole system because of a misinformed parts application.
It can work really great!! That is why I am going to use points on my stroker and I refuse to even consider any GM thingy under my hood..

I do agree with you. I'm not knocking my dual points, they work very good. I'm just looking ahead to gain some reliability and low maintenance when they fail...which is usually around 3-5k miles.

I've already moved over to an electronic voltage regulator, might as well follow suit with a higher voltage spark/ignition system.

 

[michiganhotrod1]

My vote is for a Chrysler OEM electronic ignition. I have heard complaints over the years about Pertronic, and with the OEM/ Mopar Performance system too. The difference is that every parts store on the planet can get replacement parts for the Mopar system, and most repair shops can fix them if they fail, not so with the aftermarket stuff.
What I did on some of my cars, eg. 1964 225 /6 pickup, is put the electronic hardware in the original distributor, basicly the reluctor and the plate assembly. That way you keep the existing advance curve, assuming you like it (the Mopar Performance system has a race oriented curve, might be too hot for current gas on the street). Buy the wiring harness and ICU from Mancini racing, and avoid the Chinese brands. Include a electronic voltage regulator on 69 and down models; there is a vendor that sells them in the old style "box" to keep the appearance, and for bolt in wiring.
My truck is going on 25 years with this setup.
Mark

 

[Turboomni]

I'm just looking ahead to gain some reliability and low maintenance when they fail...which is usually around 3-5k miles.

Understandable for sure. Not saying points are perfect and they do have their downfalls,but they can work very well. Many just think they never worked well but they do have a 60+years of history operating engines in the USA.

 

[Big_John]

This is what I found from a quick search.

OK, so they do list the coils as 6 or 12 volt. When I've shopped for an aftermarket coil, it's been about matching the primary resistance to the ignition system. When the primary resistance is lower, the coil should saturate faster and have a better output. Actually, you are doing the same by saying a "6 volt" coil, because a coil you would use in a 6 volt system will have a lower primary resistance.

The problem is that with a points system, you are limiting yourself to a higher primary resistance coil because the points will only flow a limited amount of current.

This is where the aftermarket ignitions, like the Pertronix, or even adapting the GM HEI, excel. They allow a greater amount of current to be passed through to the coil... and therefore you can use a lower resistance primary coil. In fact, the HEI would let you use a .3 ohm E-Core coil that runs cooler etc.

For example, I use this .6 ohm coil with my Pertronix II in my Barracuda. BTW, note there is no mention of voltage other than the Gee Whiz output voltage in this link. 45011

If you want to refer to them as "6 volt", OK, whatever... I'll agree to disagree on the verbiage. But please, if nothing else, please start to understand the difference between voltage and current.

 

[Turboomni]

So are you saying Use a 12 volt coil with points and ballast resistor?

 

[Big_John]

So are you saying Use a 12 volt coil with points and ballast resistor?

Sigh....

 

[Big_John]

I'm saying to match the primary resistance with the ignition system you have.

 

[Turboomni]

Well that is what you told me before. 12 volt coil

 

[Turboomni]

I'm saying to match the primary resistance with the ignition system you have.

Then which would be a better match, a 12 volt or a 6 volt coil with points and ballast?

 

[Big_John]

Then which would be a better match, a 12 volt or a 6 volt coil??

with what?

 

[Turboomni]

What coil should be used on a stock points ignition with ballast resistor.
1. 12 volt coil
2. 6 volt coil

 

[Big_John]

What coil should be used on a stock points ignition with ballast resistor.
1. 12 volt coil
2. 6 volt coil

What's the primary resistance of the "6 volt" and the "12 volt" coils? Is the "12 volt" coil made to be used with a ballast resistor or not?

Here's the thing... They produce all sorts of coils spec'd for different applications. If you want to find one based only on it's specs, then you'll look at the primary resistance. Around 1.5- 2 ohms is usually what you would see in a sixties Mopar application.

You can make an argument that the stock coil is meant to run on 6 volts because after you do the math, the voltage drops (because of the ballast resistor limiting the current) to 6 volts. Or you could make the argument that the car runs on a 12 volt system. This (system voltage) is obviously the way that the vendors list the coils.

 

[Turboomni]

sigh,,,,,ok, fair enough.
Factory used 6 volt coils.

 

[Big_John]

sigh,,,,,ok, fair enough.
Factory used 6 volt coils.

It's still all about the current... Mike drop.

and I'm out.....

 

[Turboomni]

Thanks for your time Big_John.

 

[70bigblockdodge]

@Turboomni
Coil magnetic field is created by amperage flowing through the coil. The longer you have the current flowing through the coil the stronger the magnetic field. When it collapses it makes a spark uses at the plugs. The dual points allow for longer current flow (dwell) creating a stronger more reliable spark, which in turn works for high rpm. The reason multi-sparks work is low rpm they keep the plugs from fouling.
The amount of windings in a coil produce a primary resistance naturally, the ballast resistor is supposed to be matched total ohms to achieve ~9 volts at the coil positive post with alternator running ~ 14-14.5volts in system. The 9volts corresponds with the system voltage drops to when starter is drawing it's huge amperage load from battery. The system as it is laid out is designed to run consistently at approximately 9 volts providing consistent spark.
The old Accel super coils, the big yellow ones came with a low ohm ballast resistor to make the amperage flow the same as stock setup, because of increased resistance in the yellow supercoil from more windings to produce a higher 45,000 output voltage compared to 27,000-30,000 of a normal oil filled.
A ignition coil is a step up transformer. It takes high amperage low voltage pulsed electricity and converts it to high voltage low amperage electricity, this is why you do not die when shocked from plug wires, no amps.
Ignition coil works like the transformer on the pole outside your house but opposite. They have high voltage 30,000- 40,000 volts stepped down to 110 with higher amps to power your house. Amperage creates heat in the wires, voltage does not. This is why a 50,000 volt electric fence is not hot temperature wise, but a 7/8 wrench across 12 volt battery terminals gets very hot.
Amperage is what does the work. It is the flow of electrons, voltage is just pressure on electrons, like pushing on a wall that does not move, no work is done. Amperage is what makes conductors get hot. When a wire grounds out on your car it melts because amperage flowed through it not voltage spiking. This is why you limit the amperage to coil not the voltage to keep it from overheating.
Coils like GM HEI have more internal resistance so they self limit their amperage from more internal windings creating more secondary(spark plug) voltage.
Hope this rambling helps.

 

[Turboomni]

Thanks man as that must have taken a bit of time. I appreciate it. I will have to re read this a few times . Some I remember. The coil is just an induction circuit correct?
While I digest that I will ask a question.
Did anyone make a dual point system that each set of points only had 4 lobes [firing only 4 cylinders ]each and one coil for each set of points?? That way the dwell angle would be much longer than the typical dual points you speak of?

 

[70bigblockdodge]

I appreciate it. I will have to re read this a few times

Probably because of my bad grammer.

Did anyone make a dual point system that each set of points only had 4 lobes [firing only 4 cylinders ]each and one coil for each set of points?? That way the dwell angle would be much longer than the typical dual points you speak of

Not that I know of. Ferrari or some other 12 cylinder probably used 2, 6 cylinder distributors.