My COIL EXPLODED
 

Car wouldn't start. Checked the coil and discovered the top plastic part had actually lifted out of the case. Never had that happen before. The ignition is 12V with Pertronix kit and matching coil. It has worked fine in the past. Coil is the oil filled Pertronix unit shown here:
https://www.amazon.com/PerTronix-400...a-568782789506

I suspect that the engine compartment heat caused the coil failure.
Would installing an aluminum coil cover like the ones shown below dissipate enough heat to protect the coil from overheating?
https://www.google.com/search?q=flat...client=gws-wiz

Or would it be better to wrap the coil in aluminum foil and foam insulation material. The coil is mounted on an aluminum bracket attached to a water pump bolt so radiator fan blows air on it. Should I relocate the coil?
Opinions welcome.

Re: My COIL EXPLODED
 

You probably don't want to hear my answer.

Re: My COIL EXPLODED
 

Go back to stock and get a Skip Haney coil. My 2¢

Re: My COIL EXPLODED
 

Or maybe an internal short caused the excessive heat. Why not just replace the coil? Probably will never happen again. Maybe replace with a regular coil cuz your flathead can never make use of that 40,000 volt boy-racer coil.

Re: My COIL EXPLODED
 

Re: My COIL EXPLODED
 

I had two of those fail in the last year. Won't buy any more and know others who have had problems also.

Re: My COIL EXPLODED
 

Bosch Blue Coil?

Re: My COIL EXPLODED
 

No it's not a BOSCH Blue coil. It's the Pertronix coil 40001 that matches the Pertronix conversion kit.
https://www.amazon.com/PerTronix-400...a-568782789506

Re: My COIL EXPLODED
 

I understand that; I was proposing a solution.

Re: My COIL EXPLODED
 

tubman, Thanks. I appreciate your suggestions and knowledge. Here's some interesting about BOSCH BLUE COILs.
https://vwparts.aircooled.net/12V-Bo...p/00-012us.htm

When I bought the Pertronix kit (ML-181)it came with the Pertronix coil # 40001 with 1.5 ohm primary resistance. I not using a condenser or a ballast resistor.

My distributor is a Mallory YL 2527501 Series 25 dual point unit converted to a Pertronix using their ML-181 kit. Pertronix told me to use their Flamethrower 1.5 ohm coil, not the 3 ohm coil.

The more I read, the more confused I get about what coil is the correct coil to use with my Pertronix.
Additional thoughts welcomed with open arms.
Thanks, JIM

Re: My COIL EXPLODED
 

All I know is that I purchased one when they were on special for my engine test stand. (Most of the engines I test run are 12 volts.) It has worked fine for me.

Re: My COIL EXPLODED
 

Check on Ebay for the Bosch coils. Sometimes you can find a deal on there for them. But like almost everything else, I am sure they have probably gone up!

Re: My COIL EXPLODED
 

Looks to me like you have it in a place where plenty of air can get to it . . . so, I'd probably just buy 2 replacement coils and keep one in the trunk.

As it is matched to the Pertronix ignition (their recommendation) - would run what they recommend, otherwise you may experience other issues (like a failed ignition component).

Re: My COIL EXPLODED
 

Also, you really don't know WHERE the heat was coming from, so kind of hard to determine if insulation would hurt or help the problem (heat from inside or outside).

Re: My COIL EXPLODED
 

This sounds like good advice to me.

Your coil is 1.5 ohm, correct for 6 volt. Are you still 6 volt?

Re: My COIL EXPLODED
 

My understanding is Petronix needs a 1.5 ohm coil. I would suggest calling their help line if you are unsure. I've found then to be very helpful.

Re: My COIL EXPLODED
 

I think Bosch has been changing colors on some coils.

The key is getting a coil with the recommended primary ohms specification for any system. If the electronic system uses a coil that no one else produces then the customer is stuck with that brand. Most electronic systems use the 3 Ohm type with modern epoxy insulation but I've heard of problems with the Pertonix coils. Few automobile electronic systems are made with a single coil in this day and age so the single coil systems are mostly relegated to the aftermarket industry with overseas manufacture.

I think I'd try an Echlin with the same or recommended ohm value but a person just never knows what your going to get now days.

Re: My COIL EXPLODED
 

That damage is from too much current to the coil. Did you ever feel how hot the coil was getting? I'd run a coil with around 3.5 ohms resistance.

Re: My COIL EXPLODED
 

THANK YOU all for your answers.
Tim: I tried calling Pertronix help line but couldn't talk to a real person.
I posed this question as the more I read about selecting the right coil, the more confused I get. I called Pertronix today but couldn't get through and talk to a real person. Here's my question.

Several years ago I converted my Mallory YL 2527501 mechanical advance dual point distributer to electronic using the Pertronix kit ML-181. At that time I was told to use the Pertronix Flamethrower coil 40001 with 1.5 ohms primary resistance. I installed this coil without using a ballast resistor. However, I keep wondering if I should instead be using the Flamethrower coil with the 3 ohm primary resistance OR should I install a 1.5 ohm ballast resistor with the 1.5 ohm coil I am currently using? I am confused. Sorry about the redundancy but I don't want to do something stupid.
THANKS, JIM in FL

Re: My COIL EXPLODED
 

I talked to a Pertronix tech about coil resistance. You can run more resistance to reduce heat. Don't run less than the unit calls for. He said the only tradeoff using more resistance is less performance at high RPM. I don't think that is a problem with a flathead.

Re: My COIL EXPLODED
 

The 40001 coil is designed for a 12V application and - and is a 1.5 Ohm coil. The instructions for the coil say that you should have a direct 12V feed to it - and you should NOT have an in-line resistor installed. (They talk about bypassing the resister if the car has one). So, I'd do exactly as they say . . .

Re: My COIL EXPLODED
 

40cpe:
Does that mean that it is better to run a 3 ohm primary resistance rather than a 1.5 ohm resistance coil?

Re: My COIL EXPLODED
 

I would think the first question the Petronix tech would ask is: is your car 6 volt or 12 volt? I would think that must make a difference.

Re: My COIL EXPLODED
 

This is what I recall the instructions saying as well.

Re: My COIL EXPLODED
 

It is clearly evident, as shown in 19Fordy's enclosed picture, that he is running an 8BA-type engine, ALL of which use the more modern, upright distributors. Even more applicable to this thread, it is also easy to see that these ignition systems use a can-type coil which is mounted adjacent to the distributor, which is the STOCK location for an 8BA engine. SKIP HANEY does not rebuild the 8BA-type coils. Your 2¢ not good today. Coop


https://www.fordbarn.com/forum/attac...2&d=1657033247

Re: My COIL EXPLODED
 

Hi Jim,

From Petronix http://www.pertronix.com.au/troubleshooting.html#ts5


"What type of coil can I use with the Ignitor? How do I check my coil's resistance? (12V negative ground only)

To determine if your systems coil is compatible with the Ignitor, some measurements should be taken prior to installation of the Ignitor. Caution… While performing this test, never leave the ignition switch on for more than 30 seconds at a time.


Set your voltmeter to a 15 or 20-volt scale. Attach an 18 or 20 AWG jumper wire from the negative coil terminal to an engine ground. Attach positive (red) lead of your voltmeter to the positive side of the coil, and the negative (black) lead to an engine ground. Turn the ignition switch to the run position. Now read the voltage at the positive coil terminal. Turn the ignition switch off. If the voltage measured is approximately 12 volts, no resistance wire is present. A typical resistance wire will provide 9 - 6 volts.


The next step is to determine the resistance in the primary ignition. Label the wires attached to the coil terminals and note their appropriate location. Make sure that the ignition switch is off and disconnect all wires from the coil. Adjust your meter to the lowest ohm scale. If you are using an analog style meter make sure to zero the needle.


Measure from the negative terminal to the positive terminal. Write your measurement down.


Now the maximum system amperage can be determined. Divide your voltage measurement by your coil resistance measurement. This will give you the system current or amperage.


Four and six cylinder engines should not exceed 4 amps. Eight cylinder engines should not exceed 8 amps. If the total amperage in your system is higher than the amount recommended for your application, you should install a ballast resistor.


Example: Voltage 12
Resistance 1.5
12 / 1.5 = 8
Total amperage is 8"


If you increase the resistance to 3 ohms, the amperage will be 4 instead of 8. I have no idea how much of a temperature difference that would make.


Glenn

Re: My COIL EXPLODED
 

Run a 3.0 Ohm coil. It's safer on your petronix uni, will produce less heat. Epoxy filled coil will be best.

Re: My COIL EXPLODED
 

Ditto on Bosch Blue. Probably a fluke that the Pertronix coil failed. They are a good product but overkill for a flathead.

Re: My COIL EXPLODED
 

I can't be right ALL the time Coop. LOL

Re: My COIL EXPLODED
 

Lawson, my wife bought me a coffee cup she said would fit me just fine. Emblazoned on it in big letters: MR. RIGHT.

Re: My COIL EXPLODED
 

Curious why you suggest this? All of the info in the directions from Petronix says use a 1.5 ohm coil.

Not arguing, just really curious.

Re: My COIL EXPLODED
 

I don't know how much resistance it will take to affect low end or idle performance. I'd be more inclined to try a lower resistance such as an early v8 resistor with the 1.5 ohm coil, but it is trial and error. The point is that MORE resistance won't harm the pertronix per my conversation with the tech. Some of the higher end Pertronix will take a coil with something like .4 ohm (IIRC).

Re: My COIL EXPLODED
 

I had the same experience you did. Top of coil forced off and oil all over. Cause, I left the key on while the car was parked. Bought a new Bosh blue coil with internal resistor and problem solved. Yes, I'm running 12 volt system.

Re: My COIL EXPLODED
 

A flathead is not a super high compression, high spark energy using engine. Higher resistance is safer on the Petronix and Stromberg electronic ignitions. Unless you run a extrmeme rotor and plug gap this will be just fine. I run a 3.3 ohm coil on customer cars without a inline resistor that have electronic distributors and have never had a issue. (personally I run points)

Re: My COIL EXPLODED
 

Is there any chance your alternator/generator is overcharging? Possibly a bad regulator . I just checked a new one wire alternator and it was putting out 16.2 volts ! Ouch , replaced with a known to be good regulator and all is well . Its ashame new no longer means good .

Re: My COIL EXPLODED
 

Coils of different primary Ohms are designed to work with certain voltages for reliability. Some folks have no idea how an induction coil works let alone what resistance works with what. When Ford developed the model A it was the first big step away from multiple trembler coils like the model T used. The model A used 1.5 Ohm can type coil and no ballast was needed on 6-volts. The V8 introduction changed the whole design of the ignition system. Marion Mallory helped Ford develope his front mounted set up. The coils were unique in design and used a short odd shaped coil core which also changed the primary and secondary coil windings. I'm not sure if they were 1.5 Ohm but I do know that they had to use a 0.8 Ohm ballast to insure they would run cool. Ford used variations of this set up till 1949 when they went back to the can type coil. No ballast was necessary with the 1.5 Ohm coil till 1956 when they changed to 12-volts. The change required a 1.3 to 1.5 Ohm ballast. Ford, GM, & Chrysler all used a ballast with a 1.5 Ohm coil.

Years went by and ballast resistors changed to ballast wires. Eventually, coils changed to 3.0 Ohm to work with no ballast. Modern materials like epoxy replaced oil and tar for internal insulation so the new coils could take the heat. It sounds to me like Pertronics is either not explaining thing well or they want to sell a lot of coils. A 1.5 Ohm coil will run too hot on 12-volts with no ballast. They expect the installer to insure the vehicle has a ballast wire or resistor without explaining that very well.

There is also the possibility that their coils are not very good quality. There should be no reason to run an oil filled coil in this day and age. All an electronic ignition system does is provide an electronic form of pulsating DC power to make the coil function. It takes half wave DC or full wave AC to step up voltage with any induction coil otherwise they don't work.

Re: My COIL EXPLODED
 

The above theory is correct...however, I ran my 35 V8 for years on 6 volt, using some sort of unmarked coil brought in from America. It has a black body and a gold sort of coloured top. Years later, when I converted that vehicle to 12 jolts, I kept the same coil, same configuration, no ballast resister [just as I used it with 6 volt], and it has run flawlessly like that for years.
Some years ago I imported a 1951 8N tractor. It too was 6 volt with the same sort of coil [black body/ gold top] When the 6 volt battery expired, I replaced it with a 12 volt battery, again leaving the coil unchanged. It too has proven trouble free.
Now, I don't know the coil resistance, however, I understand these are 6 volt coils. They run perfectly fine on 6 or 12 volts.

Re: My COIL EXPLODED
 

They sound like Ford coils.

Re: My COIL EXPLODED
 

I dunno...no markings, but they are good coils

Re: My COIL EXPLODED