Moparts

Ballast Resistor Yes or No?

Posted By: SCATPK

Ballast Resistor Yes or No? - 12/30/14 03:11 AM

Do we need a ballast resistor with an electronic ignition? Who runs one and who does not? And those who do not, have any of you experienced any failures of a coil or distributor pick up with the extra voltage? Reading this article it seems I may be leaving some power on the table.
http://www.hotrod.com/how-to/paint-body/mopp-1110-ballast-resistor-guide-ballast-blast-off/
Posted By: lewtot184

Re: Ballast Resistor Yes or No? - 12/30/14 03:23 AM

to eliminate the ballast you'll need a compatible coil. stock coils weren't designed to take a full 12 volts. personally i don't understand all the negative reactions to the ballast resister.
Posted By: mopar346

Re: Ballast Resistor Yes or No? - 12/30/14 03:35 AM

A lot of aftermarket pick ups will go bad with 12 volts constant.
Posted By: StrkrDart69

Re: Ballast Resistor Yes or No? - 12/30/14 04:15 AM

Points yes
Electronic no. Use an aftermarket performance coil.
Posted By: RapidRobert

Re: Ballast Resistor Yes or No? - 12/30/14 05:37 AM

You have ALOT of leeway on how little ballast you can get by with (always carry spares). it mainly depends on the coil selection as to how much ballast you should run & much less on what ECU you are running tho the ECU has to on/off switch the amount of current in the coil primary circuit which is the sum of your coil/ballast choice & will be affected by your choice of ballast in the long run. 35 yrs ago I ran an Accell super coil (the big yellow beast) with no ballast (OE 70's electronic dist/OE '75 chebby black HEI module) with no failure & it ran awesome. (Accell later told me to run a .7 or .8 (I forgot which) ohm ballast with that coil. Jacobs the ign people tell me that too much power can actually cavitate A/F molecules out of the spark plug gap
Posted By: Sinitro

Re: Ballast Resistor Yes or No? - 12/30/14 07:12 AM

What many don't understand is...
The ballast resistor protects the coil from overcurrent...
Its resistance increases as it gets hotter..
Traditional coils had thin internal wire windings and could not handle higher currents.

Some later coils are designed to handle higher currents, also some do not require a ballast resistor U need to check the maufacturer for their recommendations. Now the traditional oil-filled coil is being replaced with the EL transformer type design, which is more compact..

Just my $0.02...
Posted By: GY3

Re: Ballast Resistor Yes or No? - 12/30/14 12:10 PM

Use of an aftermarket ignition like the MSD 6AL does away with the ballast.
Posted By: dynorad

Re: Ballast Resistor Yes or No? - 12/30/14 08:16 PM

The ballast protects the coil and the ignition module. If you want to bypass you should replace both of these with units that can withstand the current passing through them at 14V.
Posted By: John_Kunkel

Re: Ballast Resistor Yes or No? - 12/30/14 09:09 PM


The MSD Blaster is a popular coil, the instructions state " Most late model vehicles with electronic ignitions do not require a ballast resistor, check your ignition and manufacturers specifications to determine if a ballast is required in your application."

For points they specify a ballast be used.

OTOH, Pertronix says to use a ballast if the coil isn't within a certain resistance range.
Posted By: cjskotni

Re: Ballast Resistor Yes or No? - 12/30/14 11:08 PM

Yes, you should run a ballast with the OEM coil as well as most aftermarket coils. If you don't run it, the life of the coil will be greatly reduced as it will run much hotter and with nothing to limit current going to it.

FWIW, I tried to run my MSD Blaster II coil (Mopar chrome box ECU) with no ballast and it was searing hot after 5 minutes. I went to a .25 ohm ballast which dropped the voltage to the coil to 7-8V which kept it much cooler and with no discernable drop in output to the plugs (40-45kV).

Use the ballast.
Posted By: SCATPK

Re: Ballast Resistor Yes or No? - 12/30/14 11:34 PM

I am going to change out the stock ballast resistor on my dart for one of the msd units and see what the voltage is to the plugs. Right now i am showing about 5 volts with the current setup, factory electronic distributor with chrome ecu and msd blaster coil. Seems there are various opinions on the use of a ballast resistor. Could just jump the terminals of my current resistor and see if the coil becomes smoking hot.
Posted By: Dcuda69

Re: Ballast Resistor Yes or No? - 12/30/14 11:37 PM

Quote:

A lot of aftermarket pick ups will go bad with 12 volts constant.



Not sure which aftermarket pickup coils you mean. The factory style pickup is a pulse generator(I believe MSD is also)it sees NO voltage..it creates an AC signal used as a trigger by the ECU
Posted By: goldduster318

Re: Ballast Resistor Yes or No? - 12/30/14 11:57 PM

Quote:

The ballast protects the coil and the ignition module. If you want to bypass you should replace both of these with units that can withstand the current passing through them at 14V.



Its protecting only the coil. If you check the wiring diagram, the ECU gets full battery voltage from the vehicle harness.

As mentioned earlier, the stock distributor pickup doesn't care as it's a Variable reluctance sensor and is not powered. The magnetic field creates AC voltage as the reluctor passes by the pickup.

I ran an Accel 8140 coil for years with a stock replacement ECU and never had an issue.
Posted By: Dcuda69

Re: Ballast Resistor Yes or No? - 12/31/14 12:13 AM

Quote:

Quote:

The ballast protects the coil and the ignition module. If you want to bypass you should replace both of these with units that can withstand the current passing through them at 14V.



Its protecting only the coil. If you check the wiring diagram, the ECU gets full battery voltage from the vehicle harness.

As mentioned earlier, the stock distributor pickup doesn't care as it's a Variable reluctance sensor and is not powered. The magnetic field creates AC voltage as the reluctor passes by the pickup.

I ran an Accel 8140 coil for years with a stock replacement ECU and never had an issue.



True the ECU is powered from the harness but it also carries the same current as the coil primary winding because it controls the coil negative on/off. When the coil is "on" current flows through the coil primary to ground provided by the ECU

Here's a pretty good description of system operation copy/pasted from the tech archives..just remember, any current flow through the coil primary also goes through the ECU:

The + wire supplies the power to the coil and the ECU grounds the negative part closing the circuit. This creates a magnetic field in the coil. The coil is what we call an autotransformer. When the ECU receives a signal from the magnetic pickup to fire a spark, the ECU OPENS the circuit, the magnetic field collapses and a spark is generated. A collapsing magnetic field creates a high reverse polarity voltage (energy).

The ballast resistor knocks the voltage down by a few volts to the coil (+) from 12 volts. The ballast resistor is bypassed during starting to produce a hotter spark. Run without the resistor and you will burn the coil up in a matter of minutes.

Simple actually.

Inside the distributor is the pickup and reluctor. The pickup has a magnetic field and a coil of wire. As the edges of the reluctor pass thru the pickup's magnetic field it generates a voltage in the coil, a small voltage and not enough to drive the coil.

This signal is sent to the ECU which uses it to control the coil. The ECU transforms the small pulse from the pick up into a signal of proper duration (this is where the dwell is created) to fire off the coil. It will generate a ground to the coil to allow it to charge up then remove the ground causing the spark.

The coil generates it's high voltage spark by collasping a magnetic field as described above.

The ballast resistor is not there to knock down voltage but to limit current thru the system. It's the excessive current that will burn out a coil. However, being that voltage = resistance times current any drop in current will affect voltage. But it is still the current that does the damage.
Posted By: Supercuda

Re: Ballast Resistor Yes or No? - 12/31/14 01:03 AM

Any of you ever burn your finger on the ballast?

Without it there to limit current that heat would be added to the coil.
Posted By: Dcuda69

Re: Ballast Resistor Yes or No? - 12/31/14 04:33 AM

Quote:

Any of you ever burn your finger on the ballast?

Without it there to limit current that heat would be added to the coil.



Exactly! AND the ECU!!
Posted By: goldduster318

Re: Ballast Resistor Yes or No? - 12/31/14 05:27 AM

Quote:

Quote:

Quote:

The ballast protects the coil and the ignition module. If you want to bypass you should replace both of these with units that can withstand the current passing through them at 14V.



Its protecting only the coil. If you check the wiring diagram, the ECU gets full battery voltage from the vehicle harness.

As mentioned earlier, the stock distributor pickup doesn't care as it's a Variable reluctance sensor and is not powered. The magnetic field creates AC voltage as the reluctor passes by the pickup.

I ran an Accel 8140 coil for years with a stock replacement ECU and never had an issue.



True the ECU is powered from the harness but it also carries the same current as the coil primary winding because it controls the coil negative on/off. When the coil is "on" current flows through the coil primary to ground provided by the ECU

Here's a pretty good description of system operation copy/pasted from the tech archives..just remember, any current flow through the coil primary also goes through the ECU:

The + wire supplies the power to the coil and the ECU grounds the negative part closing the circuit. This creates a magnetic field in the coil. The coil is what we call an autotransformer. When the ECU receives a signal from the magnetic pickup to fire a spark, the ECU OPENS the circuit, the magnetic field collapses and a spark is generated. A collapsing magnetic field creates a high reverse polarity voltage (energy).

The ballast resistor knocks the voltage down by a few volts to the coil (+) from 12 volts. The ballast resistor is bypassed during starting to produce a hotter spark. Run without the resistor and you will burn the coil up in a matter of minutes.

Simple actually.

Inside the distributor is the pickup and reluctor. The pickup has a magnetic field and a coil of wire. As the edges of the reluctor pass thru the pickup's magnetic field it generates a voltage in the coil, a small voltage and not enough to drive the coil.

This signal is sent to the ECU which uses it to control the coil. The ECU transforms the small pulse from the pick up into a signal of proper duration (this is where the dwell is created) to fire off the coil. It will generate a ground to the coil to allow it to charge up then remove the ground causing the spark.

The coil generates it's high voltage spark by collasping a magnetic field as described above.

The ballast resistor is not there to knock down voltage but to limit current thru the system. It's the excessive current that will burn out a coil. However, being that voltage = resistance times current any drop in current will affect voltage. But it is still the current that does the damage.



Yes, that's true that it carries that current as well, but that isn't an issue at all.

Here's the specs for the switching transistor commonly found on an orange box for reference: http://www.nteinc.com/specs/original/MJ10012.pdf

You won't be causing any ECU issue by deleting the resistor. I've gone 10 years without one with no issues.
Posted By: MidPenMopar

Re: Ballast Resistor Yes or No? - 12/31/14 06:33 AM

I have the Pertonix ignition and Pertonix matched coil on my 383 and it calls to bypass the ballast resistor. Works fine for me!
Posted By: 383man

Re: Ballast Resistor Yes or No? - 01/03/15 10:34 AM

Many electronic ign systems can eliminate the ballast if designed as they can control the dwell and current flow through the coil primary circuit by how long they want it grounded to build up a strong enough magnetic field by the electronics in the unit. Just like GM HEI eleiminated the resistance wire they used in the cars wire harness that feeds the coil primary + side that they used on their point systems right up until they eleminated points and went to HEI around 1974. Yes Ford and GM used primary resistance to drop the voltage and current flow to the coil just like Mopar only they used a resistance wire that was part of the wire harness from the ign switch to the coil. I remember that article when it ran in Mopar Muscle about 5 years or so ago as they basically said if you have electronic ign you dont need a ballast. Hymm then why did Mopar engineers still use one in their electronic ign and Ford also still used a resistance wire in their wire harness when they first went to electronic ign around 1974 with their Dura Spark ign as they called it. I have been using the old big yellow Acell Super Coil since 1999 in my cars with the MP orange ECU and a .75 ballast as its still on my 63 working great to 6500 rpm and never missing a beat running 10's. And I have never had any ign part go bad as its the same ballast I started using in 1999 when I put the setup on my Dart first and then transfered it to my 63. So should I take off my ballast for a hotter spark and chance burning up a coil since that article says so ?? Na I dont think I will ruin a good ign thats worked flawless for me. Ron
Posted By: Mattax

Re: Ballast Resistor Yes or No? - 01/03/15 06:48 PM


It depends on the ignition package.
A capacitive discharge system (like MSD 505, , 7 etc) or an indutive system that is designed to actively control the current (like the Pertronix mentioned above) will not need the resistor. Everything else was designed to use the resistor(s) for this function.

As Christopher Jacobs wrote in his book, for short WOT bursts (1/4 mile) one can try to get a little more out of the coil with a bypass switch. IIRC the purpose is to make up for the lack of time at high rpm for the coil to rebuild its field. Whether it is going to make a difference to performance will depend on what is happening in the combustion chamber.

Another variable is how the coil itself is internally designed. They can be designed to perform better at low rpms or at high rpms. It has to do with the windings. If you compare the specs for a Blaster 2 vs a stock coil you'll notice a differnce in windings.
Posted By: 383man

Re: Ballast Resistor Yes or No? - 01/03/15 06:58 PM

Yea the MSD type ign which is the multi-spark up to a certain rpm normally has both coil pos and neg hooked to the MSD control box as it controls the coil primary and can induce like 300 volts into the coil primary and most MSD type ign are designed not to use a ballast as they control the coil primary with their control box. Ron
Posted By: StrkrDart69

Re: Ballast Resistor Yes or No? - 01/03/15 07:02 PM

Quote:

Yes, you should run a ballast with the OEM coil as well as most aftermarket coils. If you don't run it, the life of the coil will be greatly reduced as it will run much hotter and with nothing to limit current going to it.

FWIW, I tried to run my MSD Blaster II coil (Mopar chrome box ECU) with no ballast and it was searing hot after 5 minutes. I went to a .25 ohm ballast which dropped the voltage to the coil to 7-8V which kept it much cooler and with no discernable drop in output to the plugs (40-45kV).

Use the ballast.



You have other issues. Ecu should not be getting hot. Also my coil does not run hot.
Posted By: Mattax

Re: Ballast Resistor Yes or No? - 01/03/15 07:17 PM

Chrysler tech when the electronic ignitions first came out
http://www.imperialclub.com/Repair/Lit/Master/292/page05.htm
Posted By: Supercuda

Re: Ballast Resistor Yes or No? - 01/03/15 07:52 PM

Quote:

Quote:

Yes, you should run a ballast with the OEM coil as well as most aftermarket coils. If you don't run it, the life of the coil will be greatly reduced as it will run much hotter and with nothing to limit current going to it.

FWIW, I tried to run my MSD Blaster II coil (Mopar chrome box ECU) with no ballast and it was searing hot after 5 minutes. I went to a .25 ohm ballast which dropped the voltage to the coil to 7-8V which kept it much cooler and with no discernable drop in output to the plugs (40-45kV).

Use the ballast.



You have other issues. Ecu should not be getting hot. Also my coil does not run hot.



Yeah, the problem is lack of a ballast resistor.

To quote MSD

Most late model vehicles with electronic ignitions do not require a ballast resistor, check your ignition and manufacturers specifications to determine if a ballast is required in your application.

Ford and GM put a resistance wire in the loom in lieu of a ballast resistor, Mopar uses a ballast. Dunno what AMC did. So on a GM and Ford you would not need a ballast as you would be doubling up, on a Mopar you do.
Posted By: StrkrDart69

Re: Ballast Resistor Yes or No? - 01/03/15 08:51 PM

Go ahead and keep using a ballast resistor.
Posted By: Sinitro

Re: Ballast Resistor Yes or No? - 01/03/15 11:12 PM

Quote:



Its protecting only the coil. If you check the wiring diagram, the ECU gets full battery voltage from the vehicle harness.




Depends upon the year...
Certain Mopars used a dual element ballast resistor, this connected to pin 5 of the ECU, protecting it. For early ECU systems, the Mopar engineers were concerned about max voltage to the ECU as to protect its power transistor..

Just my $0.02...
Posted By: Supercuda

Re: Ballast Resistor Yes or No? - 01/03/15 11:21 PM

Quote:

Go ahead and keep using a ballast resistor.



You wouldn't happen to be an electrician now would you?
Posted By: StrkrDart69

Re: Ballast Resistor Yes or No? - 01/04/15 01:33 AM

Quote:

Quote:

Go ahead and keep using a ballast resistor.



You wouldn't happen to be an electrician now would you?


No I am a yawner.
Posted By: 71GTX471

Re: Ballast Resistor Yes or No? - 01/04/15 03:16 AM

The 72 electronic ign. intro book was good reading always good to refresh your self & picked up some little tidbits of info.
Posted By: cjskotni

Re: Ballast Resistor Yes or No? - 01/05/15 01:47 PM

Quote:

Quote:

Yes, you should run a ballast with the OEM coil as well as most aftermarket coils. If you don't run it, the life of the coil will be greatly reduced as it will run much hotter and with nothing to limit current going to it.

FWIW, I tried to run my MSD Blaster II coil (Mopar chrome box ECU) with no ballast and it was searing hot after 5 minutes. I went to a .25 ohm ballast which dropped the voltage to the coil to 7-8V which kept it much cooler and with no discernable drop in output to the plugs (40-45kV).

Use the ballast.



You have other issues. Ecu should not be getting hot. Also my coil does not run hot.



My coil was running hot, not the ECU.
Posted By: Supercuda

Re: Ballast Resistor Yes or No? - 01/05/15 04:21 PM

Quote:

Quote:

Quote:

Go ahead and keep using a ballast resistor.



You wouldn't happen to be an electrician now would you?


No I am a yawner.



Yes, it's things like your statements that make me yawn. Das ist nicht nur nicht richtig, es ist nicht einmal falsch!
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