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

[commando1]

Probably because of my bad grammer.

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Wanker

 

[James Romano]

OK, in prep for the new ignition, I replaced the starter relay and cleaned all the wiring up. Took out the Horn relay, wired it out and polished it out. Looks new. Put in the 14 gauge fusible link and ran 10 gauge to the alternator for the by-pass charging circuit. What a must have that is. I can tell right away it was working as I got a solid 13.8 at the battery during normal idle. Before, I was in the mid 12's and needed to bump the throttle to get the charge circuit up and running.

No brainer mod that should be done to any car, regardless of keeping it OEM, just like the dual master cylinder upgrade. If you have any intention of driving your car around. I'm much happier knowing all the current is flowing through a solid line, rather than a 50+ year old firewall connector with unknown integrity.

Ordered the Pertronix Ignitor II and the Firestorm II coil to match it up. Went with the epoxy unit. Seemed like the better choice.

 

[Mike66Chryslers]

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 volt cars and the reason for the ballast. 12 volt coils Do not work well on points ignition with a ballast resistor as I assumed.
They [6 volt coils] were a carry over from 6 volt ignitions of the 50's and before and the ballast kept them alive on 12 volts in the 1960's when 12 volts were then norm..
I guess 0n 12 volts the points would burn up yes??,,,,Yes,,of course they would.

It's not that 6-volt coils with ballast resistor were a lazy holdover from 50's ignition systems, they are an intentional feature of the ignition system in our cars! @Big_John has raised some excellent points, but he also forgot about this one: When you're cranking the starter, the ignition system voltage drops because of 1)voltage drop in the wires at high current levels (google "I-squared-R losses") and 2) the battery can't convert chemical energy to electrical energy fast enough at such a high current draw. During cranking the ballast resistor is bypassed to provide full system voltage to make starting easier. You can't bypass the resistance if you use a coil with a higher internal resistance to eliminate the ballast resistor!

This is probably less of an issue now because battery technology has improved and our cars aren't driven in extreme cold where battery output is reduced while the starter has a harder time cranking thereby drawing more current. Consequently, I'm not surprised if a lot of people have had good success swapping to a "12-volt" coil to eliminate the ballast resistor. It was still there for a good reason.

Coils are labelled as "6-volt" or "12-volt" as a dumbed-down terminology for non-electrical people. Really it's not about voltage or current independently, but POWER (Watts), which is voltage X current. More specifically, a lot of power through the coil is converted to heat. Too much power and it will overheat and fail. The ballast resistor is there to limit coil power. The actual resistance of a ballast resistor varies somewhat with temperature, lower resistance when it is colder and higher resistance when it is hotter. This is another feature of the ballast resistor, because it varies coil power with underhood temperature, providing a higher-powered spark when it's safe to do so.

HEI and similar systems don't need a ballast resistor because the ECU in those systems is more advanced and has an internal current regulator to limit the current. It's not that the HEI coils have higher internal resistance. If you swap-in an aftermarket coil in an HEI system which can take higher power, you're supposed to also swap-in the HEI module that is matched to it to take advantage of the coil.

On side-note, an ignition coil is actually in ingenious device which uses properties of both an inductor and a transformer.

 

[Big_John]

It's not that 6-volt coils with ballast resistor were a lazy holdover from 50's ignition systems, they are an intentional feature of the ignition system in our cars! @Big_John has raised some excellent points, but he also forgot about this one: When you're cranking the starter, the ignition system voltage drops because of 1)voltage drop in the wires at high current levels (google "I-squared-R losses") and 2) the battery can't convert chemical energy to electrical energy fast enough at such a high current draw. During cranking the ballast resistor is bypassed to provide full system voltage to make starting easier. You can't bypass the resistance if you use a coil with a higher internal resistance to eliminate the ballast resistor!

This is probably less of an issue now because battery technology has improved and our cars aren't driven in extreme cold where battery output is reduced while the starter has a harder time cranking thereby drawing more current. Consequently, I'm not surprised if a lot of people have had good success swapping to a "12-volt" coil to eliminate the ballast resistor. It was still there for a good reason.

Coils are labelled as "6-volt" or "12-volt" as a dumbed-down terminology for non-electrical people. Really it's not about voltage or current independently, but POWER, which is voltage X current. More specifically, a lot of power through the coil is converted to heat. Too much power and it will overheat and fail. The ballast resistor is there to limit coil power. The actual resistance of a ballast resistor varies somewhat with temperature, lower resistance when it is colder and higher resistance when it is hotter. This is another feature of the ballast resistor, because it varies coil power with underhood temperature, providing a higher-powered spark when it's safe to do so.

HEI and similar systems don't need a ballast resistor because the ECU in those systems is more advanced and has an internal current regulator to limit the current. It's not that the HEI coils have higher internal resistance. If you swap-in an aftermarket coil in an HEI system which can take higher power, you're supposed to also swap-in the HEI module that is matched to it to take advantage of the coil.

You have much more knowledge in this than I do. I know some basics and then it gets over my head really fast. My late brother was the electrical engineer, not me... LOL.

I did leave the part about the BR being bypassed as I thought it would confuse things...

"dumbed-down terminology for non-electrical people" is perfect.

 

[Turboomni]

Thanks for the reply Mike66Chryslers. A good deal of your reply was over my head but I appreciate it. I understand if you run a 6 volt coil on 12 volts [no ballast] it will most likely overheat and also burn up points. It is also my understanding that a coil rated at 6 volts for dummies as you say opposed to 12 volts that each will be wound in such a way to get the most spark voltage reliably from their rated voltage. Each is wound,wired whatever differently. Correct me if I am wrong. My goal here is not to bunch up anyone's panties. I have been trying to find the answer for awhile. I have run a 6 volt coil with points and ballast going on 4 years now with great results.
So I will ask you this question again as no one has yet given me an answer.

You go to your autoparts store for tune up parts for your new to you 68 Newport 383. You ask for points,plugs,ballast,cap,rotor,coil etc. He looks them up and gives them to you. Looks up the coil and says "they show a 6 volt and a 12 volt coil". In your opinion which one do you pick?

 

[James Romano]

After what I read here and can understand, I would go with a 12 volt... Reason is the 6 volt is only that, 6 volts. If the ballast is set to reduce to 9 volts, you are overpowering the 6 volt coil. You have some play there when it comes to the system.

Plus, as I discovered... My ballast was broken in half held on by the wound wire. I only discovered this because I decided to check it. I don't trust these things at all. If it breaks, you're now running 12 volts into a 6 volt coil with no protection. Undervoltage is usually no where near as devastating as overvoltage

 

[Mike66Chryslers]

Thanks for the reply Mike66Chryslers. A good deal of your reply was over my head but I appreciate it. I understand if you run a 6 volt coil on 12 volts [no ballast] it will most likely overheat and also burn up points. It is also my understanding that a coil rated at 6 volts for dummies as you say opposed to 12 volts that each will be wound in such a way to get the most spark voltage reliably from their rated voltage. Each is wound,wired whatever differently. Correct me if I am wrong. My goal here is not to bunch up anyone's panties. I have been trying to find the answer for awhile. I have run a 6 volt coil with points and ballast going on 4 years now with great results.
So I will ask you this question again as no one has yet given me an answer.

You go to your autoparts store for tune up parts for your new to you 68 Newport 383. You ask for points,plugs,ballast,cap,rotor,coil etc. He looks them up and gives them to you. Looks up the coil and says "they show a 6 volt and a 12 volt coil". In your opinion which one do you pick?

A coil marked "12V USE WITH EXTERNAL RESISTOR" is a pretty safe bet. What you really want is a coil with a primary resistance around 1.5 ohms, but that spec seems difficult to find. If they have one on the shelf, ask to see the 12V coil that their computer says fits your car. If it says "12V USE WITH EXTERNAL RESISTOR" then that's probably what you want.

If you want a specific recommendation, the Standard Motor Products (SMP) #UC12 is an OEM type coil with a primary resistance of 1.3-1.5 ohms. For more money, you could get an SMP Blue Streak #UC12X, which is the same coil made with upgraded materials. I actually ran one of those on my Windsor for years. I was running an Mopar orange box conversion, not points, but that coil will work fine with points.

 

[Turboomni]

After what I read here and can understand, I would go with a 12 volt... Reason is the 6 volt is only that, 6 volts. If the ballast is set to reduce to 9 volts, you are overpowering the 6 volt coil. You have some play there when it comes to the system.

Mine reads 7 to 8 volts after the ballast but no matter, a 12 volt coil sees well over 13 volts yes?

 

[James Romano]

Mine reads 7 to 8 volts after the ballast but no matter, a 12 volt coil sees well over 13 volts yes?

Yes... Almost everything electric has some built in overv voltage by design until it burns up. Meaning it will surge to maybe 13.5 then fry

Then that's your ultimate answer... The meter will tell you what to do.

 

[Turboomni]

Tell me what? Its the same for both . 1 to 2 volts over the spec.
Sorry maybe I don't understand what your saying.

 

[James Romano]

Lol.. if you're getting 7 to 8 volts on the output side of the ballast, then you should go with a 12 volt coil. 6 volt coil will be running at a constant over voltage.

Maybe I'm wrong, but that's how I would approach it

 

[Turboomni]

Why run a 12 volt coil on 8 volts,,,,it usually runs on up to 14 volts depending.

 

[Turboomni]

OK! I finally got pretty much the whole answer between Mike66Chryslers and a guy on a old Ford forum.
So as long as a coil is 1.5 ohms they will work after a ballast whether or not it rated for dummy's at 6 or 12 volts as I think Mike66Chrysler said.
The problem lies when a 12 volt coil is 3 ohms and you try to use 6 volts . It will not work well at all. This is regarding 6 volt ignition cars but I think it still applies.

12 volt coil on a 6 volt engine - The Ford Barn






Senior Member

Join Date: May 2010
Location: Young Harris, GA
Posts: 1,406

Re: 12 volt coil on a 6 volt engine
Quote:
Originally Posted by Gabalus
Hello,

My 6 volt coil failed and I just have a 12 volt coil to run tomorrow morning.
What do you think about that ? Does it work ? Very well ? Limits ?

Thank you
------------------------
First, let me ask: What do you mean by "a 12 volt coil"?

Can you measure the resistance with an ohm meter across the the 2 coil posts?

Some "12 volt coils" read out at about 1.5 ohms and require an external ballast resistor to be able to use them on a 12 volt car. You can run a 1.5 ohm "12 volt coil" on a 6 volt car without a ballast resistor and it will run great.

Some "12 volt coils" read out at about 3 ohms and can really only be used on a 12 volt car. The spark out of this "12 volt coil" when used on a 6 volt car will be very weak. The car might start but you won't like how it runs with the weak spark.

If you have a NAPA near you, you can get an IC-12 coil for your 6 volt car that will be around 1.5 ohms.

Lots of confusion around coils and volts. I hope this helps.
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[The Captain]

Had a Chrysler with a Pertronix that a previous owner installed. Car ran good but idled a bit rough. I found a bunch of play in the distributor because of worn shaft bushings. Changed the distributor housing from spare parts I had and the issue was fixed.

 

[Turboomni]

So I guess if you are looking for a coil for your points ignition ,your best bet unless they specify ohms which most do not is to buy a coil for dummies that say 6 volt which will be most likely 1.5 ohms or one 12 volt that someone says has the correct 1.5 ohms even though it says 12 volts. But before installing make sure to check the coil with your ohm meter. Make sure it is 1.5 ohms or there abouts. Not 3 ohms or you may be very sorry.
I am glad this is over and done with.

 

[Big_John]

So I guess if you are looking for a coil for your points ignition ,your best bet unless they specify ohms which most do not is to buy a coil for dummies that say 6 volt which will be most likely 1.5 ohms or one 12 volt that someone says has the correct 1.5 ohms even though it says 12 volts. But before installing make sure to check the coil with your ohm meter. Make sure it is 1.5 ohms or there abouts. Not 3 ohms or you may be very sorry.
I am glad this is over and done with.

You could just buy a coil that specs the ohm rating.
Examples: canister_coils

ACCEL Super Stock Coils

JEGS 40105: High Energy Ignition Coil Red | JEGS

Summit Racing® High Output Ignition Coils SUM-G5219

Most of the aftermarket performance coils do show that spec.

 

[3175375]

Thought I would leave this. My copy is on its way...

 

[James Romano]

Ignitor II is in... And holy ****... She really came alive!! Lots of power out of her now. I'm satisfied so far. Added an NOS electric voltage regulator I found on eBay. Looks like OEM stock. Very happy with the change over. Was piss easy and made a huge difference in the power of the motor. Found my old points were worn out as well.

All I had to do was re-time the engine.