Balast resistor or no?

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H8z2luze

H8z2luze

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OK so I'm finding conflicting info on this. The setup I have is the pro form electronic ignition system with a edlebrock 12v max fire coil. The coil itself says a balast resistor is not required. Couldn't get the car to start with the one that's in there hooked up. Jumped the wire and it ran so I just left it jumped after researching and thought it was OK with that coil. BUT... Car started running bad which I think was bad gas cause it was pulling from the tank for the first time and has been sitting. So it died while I was adjusting the carb and I forgot to turn it off. Well the hour or so I took cleaning the carb and doing whatever I touched the alt pulley and it as hot. I was like that's weird... Touched the coil... Super hot. My temp gun read 165 degrees on the can. So I tried to start the car and it just popped a couple times. Put my spark tester on it and it has intermittent weak spark. So I figure I burned up the coil. My question is... Is this because I didn't have a resistor or because I left the key on? Thanks in advance guys.
 
Key on prob. They draw alot more not cycling then cycling on electronic, points depend if they are closed or not.
 
The "usual problem" with eliminating the ballast is that you somehow don't get the bypass wire connected. What you need to do either physically, but certainly electrically, is to connect the two ballast wires, then use the old coil+ wire to feed the new system

HOW AND WHY

The ballast receives power with the key in "run" from what is called IGN1 from the key. THIS GOES DEAD when cranking the starter.

Power for start to the igntion comes from the bypass cirucuit, IGN2. This is ONLY hot during cranking, comes from a dedicated contact in the igntiion switch and feeds the coil+ side of the ballast (usually brown)
 
67Dart273 said:
The "usual problem" with eliminating the ballast is that you somehow don't get the bypass wire connected. What you need to do either physically, but certainly electrically, is to connect the two ballast wires, then use the old coil+ wire to feed the new system
Click to expand...

Here's another question. Is there any downside to running the resistor? If not I'll just put a new one in lol.
 
H8z2luze said:
Here's another question. Is there any downside to running the resistor? If not I'll just put a new one in lol.
Click to expand...
Yes. On a coil that does not require a ballast, you will not have a full 12V to the ignition, as it is designed.
 
RustyRatRod said:
Yes. On a coil that does not require a ballast, you will not have a full 12V to the ignition, as it is designed.
Click to expand...

Gotcha. Is there a guide to exactly what wire goes where when eliminating the resistor? I'm a visual guy unfortunately. I took the wires off the resistor and used a butt connector to splice them together. But above he said to wire the + side from the coil into the new system? I assume this system came with directions but I got this motor already set up with it.
 
There are two wires that run from the ignition switch to the ballast. One is the 12V run wire that's hot when the switch is on. The other is the "start" wire that's only hot in the start position. Go over to mymopar.com and download a factory service manual for your car....."WHATEVER" it is as you've not said yet. They don't have them available for everything so if they don't have one for your make and model, got one that's close. You'll need to see which two wires are the run (Ignition 1) and start (Ignition 2) and wire those two together. Then from there, you wire in the wire feeding the positive side of the coil.
 
RustyRatRod said:
There are two wires that run from the ignition switch to the ballast. One is the 12V run wire that's hot when the switch is on. The other is the "start" wire that's only hot in the start position. Go over to mymopar.com and download a factory service manual for your car....."WHATEVER" it is as you've not said yet. They don't have them available for everything so if they don't have one for your make and model, got one that's close. You'll need to see which two wires are the run (Ignition 1) and start (Ignition 2) and wire those two together. Then from there, you wire in the wire feeding the positive side of the coil.
Click to expand...
Oh I guess that might help huh haha. It's a 72 Duster original 318 car but the engine is a 318 out of a 69 D100. Thanks alot for the info that's awesome.
 
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I ran that same Edelbrock 22739 1.4 OHM coil with an factory .5 OHM Ballast Resistor this past spring

Once the coil got hot at idle , the engine would just die - Always restarted instantly , but got really annoying at stop lights if you know what I mean , just idling fine and die

In all honesty I thought I had a carb issue after winter storage so that was the first thing I looked into

But then I remembered changing to this coil right before I put the car away for winter storage

Swapped it out for my trusted Standard UC12 and the problem was solved - Perfect idle for as long as I had gas in the tank
 
In da box - Read NOTE
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If you have the same coil as listed in post #10, it says NOT for elec ign.
However it should work ok with the factory ballast res iiiiiiiiiiiiiiiiiiiif your box is an inductive ign box [ similar to, or same as Ch ECU ]. It will work because the coil sees the box as merely a 'switch' that switches power on/off like the points did. CD igns [ MSD 6X boxes etc ] work differently & are not compatible.
 
That Edelbrock coil DID NOT work with a factory ECU and .5 OHM Dual Ballast Resistor

That was the point (No pun intended) I was trying to make with my post

Coil got hot at idle and shut down

And yes I am familiar with CDI versus Inductive

Peace Scott
 
One of the big issues with mixing ignition systems parts is that you can’t easily measure what is important. People talk about voltage because that can be easily measured. What is really important is the current through the coil. Yeah, I know they are related by ohms law, but it is much easier to understand when talking about current.

An ignition system is designed to work with a specific ballast resistor & coil. Let’s say you have a 0.5 ohm ballast resistor and a 1.5 ohm coil. Add them together & that is 2 ohms. Using ohms law, 12 volts divided by 2 ohms is 6 amps. So your ignition module is designed to carry 6 amps.

What if you took out the ballast? Now the current is 12 v / 1.5 ohms = 8 amps, a 25% increase. This over current may damage your ecu.

Since the current is not DC, it can’t be easily measured without special equipment, like an oscilloscope. The next best thing to do is to keep the sum of your ballast resistor and coil the same as recommended for your ignition module.

A lot of aftermarket ignition systems never specify what current they can drive. They only specify what coil to use. Mixing & matching may be hard to do. If you use the same resistance coil and ballast combination the ecu manufacturers recommend, you should be ok.

Using matching ignition system parts is the easy way to avoid headaches.
 
Mike69cuda said:
... Using matching ignition system parts is the easy way to avoid headaches.
Click to expand...
That is why I used the GM 8-pin HEI module & coil in my 3 old Mopars. A factory GM cable connects the two. All you need it to supply 12 V IGN power, ground the module at its mounting screw, and connect the Mopar e-distributor pickup wire pair to the module using its connector (get polarity right, shine timing lamp at distributor reluctor wheel to assure teeth align when flashing). Tach output wire provided and can use extra connector to command spark timing (optional).
 
Mike69cuda said:
One of the big issues with mixing ignition systems parts is that you can’t easily measure what is important. People talk about voltage because that can be easily measured. What is really important is the current through the coil. Yeah, I know they are related by ohms law, but it is much easier to understand when talking about current.

An ignition system is designed to work with a specific ballast resistor & coil. Let’s say you have a 0.5 ohm ballast resistor and a 1.5 ohm coil. Add them together & that is 2 ohms. Using ohms law, 12 volts divided by 2 ohms is 6 amps. So your ignition module is designed to carry 6 amps.

What if you took out the ballast? Now the current is 12 v / 1.5 ohms = 8 amps, a 25% increase. This over current may damage your ecu.

Since the current is not DC, it can’t be easily measured without special equipment, like an oscilloscope. The next best thing to do is to keep the sum of your ballast resistor and coil the same as recommended for your ignition module.

A lot of aftermarket ignition systems never specify what current they can drive. They only specify what coil to use. Mixing & matching may be hard to do. If you use the same resistance coil and ballast combination the ecu manufacturers recommend, you should be ok.

Using matching ignition system parts is the easy way to avoid headaches.
Click to expand...

And how is this accomplished when everything is made in Mexico or China today

Thanx Scott
 
bee1971 said:
And how is this accomplished when everything is made in Mexico or China today

Thanx Scott
Click to expand...

I don’t think it matters where it is made. We shouldn’t confuse the quality of parts with compatibility of parts.

For example: If you buy a PerTronix ignition, use the coil that they suggest. Use the ballast they suggest. If they don't specify a ballast, don’t use one.

The biggest problem seems to be mixing parts. If you buy a PerTronix ignition & Accel coil, then who knows what you got unless you understand how to figure it out.

Aftermarket and oem ignitions are designed as a complete system. The parts work together. Try plugging your tv into a 220v outlet & see how that works out for you. Those two thing are not designed to work together.
 
Newsflash!
Coils WILL get hot at idle with points & the Ch ECU. That is because:
- neither has dwell control
- dwell is extended to prevent high speed misfires
- but this means because the dwell is fixed, there is more dwell period at idle where it is not needed
- so the coil heats up at idle because it is switched 'on' longer than it needs to be

One of the benefits of GMs HEI is variable dwell, which is reduced at idle to reduce coil heating.
 
If it helps at all this is the ignition system I have.. However it came on the car and the guy I got it from did say he ran this edlebrock coil and ran it through the balast resistor that was in his truck originally and it worked fine. So I'm really not sure what direction to go from here lol. Should I just get a stock coil and balast? What's the best route?

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Do Edel make more than one ign coil? Do you know if it is the one shown in post #10?
And the coil worked fine? Maybe it is not the problem. Although only part of the coil wiring is shown in post #10, it shows the coil [+] connected direct to 12v, no ballast res??? And it says for use with points only & as far as I am aware all points systems used a ballast resistor! So contradictory!
 
Bewy said:
Do Edel make more than one ign coil? Do you know if it is the one shown in post #10?
And the coil worked fine? Maybe it is not the problem. Although only part of the coil wiring is shown in post #10, it shows the coil [+] connected direct to 12v, no ballast res??? And it says for use with points only & as far as I am aware all points systems used a ballast resistor! So contradictory!
Click to expand...

Yes I believe that is the one. I know it's 12v and 1.4 ohms.
 
I cannot understand why it would not work with the Ch ECU. The instructions are contradictory, so who knows.
I do know this, as I stated in post 11: with the points, the coil sees an on/off switch to switch current flow on/off. The ECU does the same, but uses a transistor. Coil sees no difference.
 
Bewy said:
Newsflash!
Coils WILL get hot at idle with points & the Ch ECU. That is because:
- neither has dwell control
- dwell is extended to prevent high speed misfires
- but this means because the dwell is fixed, there is more dwell period at idle where it is not needed
- so the coil heats up at idle because it is switched 'on' longer than it needs to be

One of the benefits of GMs HEI is variable dwell, which is reduced at idle to reduce coil heating.
Click to expand...


Edelbrock coil shuts down at idle when hot

Standard UC12 coil does not

Both are oil filled canister 1.4 OHM coils running a factory Mopar .5 OHM Dual Ballast Resistor

Thank You
 
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Now , if I was really bored , damn rain today

I could try the Edelbrock coil with an Mopar 1.2 OHM Ballast Resistor instead and see what happens

My point is

I have tested so many canister coils , different OHM Ballast Resistors , all in relation with Factory ECUs , Mopar Performance , Standard LX101

Like others have stated (Quality Control in China and Mismatched Ignition)

These Chinese ignition coils are always the weak link on what works and what doesn’t

If you have a "Made In The USA" canister oil filled coil - And it works fine , it’s worth it’s weight in gold
 
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Not just overseas coils that fail. I had a Mallory, made in USA, E core coil, DOA. Summit offered me a refund, another M coil or a different brand. I chose a different brand.
 
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