Ballast resistor

Electrical & Ignition

  1. PolaraFury

    PolaraFury Member

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    Hello,

    I have a 67 Satellite with a 400, 727, upgraded ignition system and the garden variety of go fast parts.

    It keeps blowing the ballast resistor. I just replaced it 3 weeks ago and it needs a new one. (I bought two spares and they are both junk. I left them in the glove box and they got tossed around)

    Any ideas on why the system it killing the ballast resistor?

    Thank you
     
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    • wish4hemi

      wish4hemi Well-Known Member

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      What do you mean by “blowing the ballast resistor?” Can you physically see that the resistor wire is burnt in two?
       
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      • PolaraFury

        PolaraFury Member

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        They just quit working. No visual evidence because they are sealed.
         
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        • Nacho-RT74

          Nacho-RT74 Well-Known Member

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          I think in 20 years having my car most of the time as a driver never have blown up a Ballast. Have you tested continuity on it ?
           
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          • wish4hemi

            wish4hemi Well-Known Member

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            Agree. There’s a good chance the ballast resistor isn’t the problem. Is the resistor matched to the ignition coil’s specifications?
             
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            • AR67GTX

              AR67GTX Well-Known Member

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              Sealed? That doesn't sound right. Those things get hot as heck.
               
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              • PolaraFury

                PolaraFury Member

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                The one on the car is reading .8 ohms and the two “new spares” read 1.1 ohms.

                it’s my understanding that they need to read 1.2 or better.
                 
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                • Nacho-RT74

                  Nacho-RT74 Well-Known Member

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                  They are all good. You have a problem elsewhere but not on ballast.

                  Performance ballast use to be on .5-.8 ohms rate. Stock into 1-1.5 ohms rate, depending if electronic or points ignition.
                   
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                  • Nacho-RT74

                    Nacho-RT74 Well-Known Member

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                    Some are sealed, some not
                     
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                    • RJRENTON

                      RJRENTON FBBO Gold Member FBBO Gold Member

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                      IMO....
                      it depends on which coil is used. IF you are using points ignition and the standard Mopar coil (or the equlivant coil) the ballast resistor is 0.5 ohms. IF you are using the Mopar electronic conversion ignition system ("Orange box") the ballast resistor is 0.8 ohms. IF switching to a High Voltage coil, the ballast resistor MUST BE MATCHED TO THE COIL. When switching to a high output coil, and the ballast resistor is changed, the "Orange box" will likely fail, perhaps not immediately, but later at the most inopportune time, because the large transistor on the orange box has failed. The resistor limits the current the coil consumes and the transistor on the orange box must switch this current off/on for each spark produced.
                      The best ballast resistor have the open back where you can see the resistor element. The worst resistor are sealed on the back where the resistor element is NOT visible. Sometimes the sealed resistors are marked by the manufacturers name...ive seen the "DALE" name. If it this type that has failed, usually open .. no resistance...the don't "blow" but fail open and no voltage gets to the coil and orange box. The failure is attributed to overheating of the resistor element.
                      When seeking a replacement ballast resistor, inquire to the ohms value and brand (manufacturer) of the replacement...the counter person will hand you what ever the computer says you need....not what you want....ASK!!
                      BOB RENTON
                       
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                      • Xp29h

                        Xp29h FBBO Gold Member FBBO Gold Member

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                        You’ve got great info if you’re running stuff listed above. I might have missed it here but if you upgraded to go fast MSD type ignition box....those doesn’t require a ballast because they want the volts. If the ballast is left in, doesn’t get the volts it needs to operate properly but If you did install MSD type, maybe the ballast just doesn’t like it..again I might have misunderstood what it was you installed.. so may be way off base.. anyway good luck!
                         
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                        • PolaraFury

                          PolaraFury Member

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                          It appears to be a Chrysler electronic ignition system and it has a MSD coil
                           
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                          • moparedtn

                            moparedtn Ed on the Ridge FBBO Gold Member

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                            Same setup I'm running - and I'm still a bit fuzzy on what resistor to use. :)
                            What IS concerning on mine, though, is the presence of what appears to be
                            some light oil around the top seal of the MSD Blaster II coil.
                             
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                            • PolaraFury

                              PolaraFury Member

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                              I bought it about a month ago from Gateway in Detroit. The dealer is sending me a pile of receipts and other paperwork. Hopefully I can get some answers to a few questions I have bouncing around in my head.
                               
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                              • RJRENTON

                                RJRENTON FBBO Gold Member FBBO Gold Member

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                                If it is the Chrysler electronic ignition system, has the OP checked the coil's requirements (presumably an MSD coil and which model) in terms of if a ballast resistor is required, and its value, or not. And can the Chrysler electronic ignition work with the MSD coil? These retrofit systems are usually well coordinated and substituted components can cause premature failures....in spite of what you have heard.
                                BOB RENTON
                                 
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                                • Bee1971

                                  Bee1971 Well-Known Member

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                                  Reading your posts , you said you kept blowing your ballast resistors

                                  Now that you have tested and verified the ohm readings , in fact your ballast resistors are fine

                                  So what is the problem with the vehicle

                                  Doesn’t start ?

                                  Starts and dies

                                  Won’t turn over
                                   
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                                  • RJRENTON

                                    RJRENTON FBBO Gold Member FBBO Gold Member

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                                    USUALLY, when a coil starts to leak its insulating fluid (oil) the case seal has been compromised and should be replaced. If a sufficient quantity of insulation oil has escaped, the windings will overheat and eveventually fail....usually at the most inopportune time.
                                    BOB RENTON
                                     
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                                    • moparedtn

                                      moparedtn Ed on the Ridge FBBO Gold Member

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                                      Yes sir, replacement is definitely in the cards - but can that phenomena be directly related to using
                                      the wrong ballast resistor?
                                       
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                                      • 383man

                                        383man Well-Known Member

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                                        I would not run Mopar ign with the MSD coil. Many coils for the MSD have much different resistance (ohms) value's then a standard coil for non multi-spark systems. Cant say thats your problem but I would check both windings on that coil and see what ohms they read and compare it to the coil Mopar recommends. My average rule of thumb for a standard point and electric ign coil is about 1 ohm on the primary winding and about 10'000 on the secondary. Thats just an average I use if I don't have a book with the proper specs with me. Its just ballpark. And I have seen some MSD coils with only about 3000 ohms on the secondary windings so they can be different. I can't remember the primary winding reading on the MSD coil off the top of my head. Ron
                                         
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                                        • Nacho-RT74

                                          Nacho-RT74 Well-Known Member

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                                          Somewhere I read the unsealed ones are called “thermal” and the sealed ones “non-thermal” alowing or not to be affected by the engine bay temperature to provide more or less current per requirements.
                                           
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