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Too much ballast?

Started by myk, April 10, 2008, 06:53:03 PM

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myk

Years ago, when I first installed my MP electronic ignition and MSD 6, I ended up installing a 2nd ballast resistor. That resistor was hooked up to the + wire from the engine harness that used to go to the + coil.  The other end of the resistor was hooked up to the + wire from the MSD.

Fast forward to now and I've been told by all including MSD that the 2nd resistor isn't necessary and was probably interfering with the performance of my electrical system.  I don't get resistors and therefor don't understand what harm that 2nd resistor could have done.  Any ideas? 

In any case, I took out the 2nd resistor and spliced the two wires together, but suddenly I noticed that the car is recharging the battery better than before? Could that 2nd resistor have interefered with battery charging?  What else can I see now that the 2nd resistor is gone? 
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Ghoste

The resistor does just what it's name implies, it resists the normal flow of current.  The MSD utilizes a higher current and having the resistor in there was shortchanging it's ability to do that.

myk

Ok, makes sense.  So, is there a way to determine whether there's too much energy coming from the system, short of frying the car's electronics? Also, as I said before, would this 2nd resistor have affected my charging system as well?

Funny thing is, I can almost swear I can remember the instructions including that 2nd resistor.  Oh well, that's youth for ya.

-Ghoste, I noticed in another thread that you run an MSD ignition and no longer have a ballast resistor.  Are you running an MSD box as well or are you refering to an MSD distributor and ECU?  If that allows you to run without a ballast resistor how does the wiring look?



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Ghoste

I run an MSD6/AL into a Mopar Performance electronic distributor with an MSD Blaster coil.  The wiring is as per the MSD instruction for an MSD.
There are a few reasons for running a ballast with a stock system but the symplified version is this.  The engine needs full current at startup to fire the cold plugs.  Once it is warmed up the ballast resistor begins to restrict current (as current passes through it, it heats up and it's resistance increases which is why they are mounted in the big ceramic insulator and still get so hot to touch).  The lower current flow is to protect the points and coil from burning up.
The MSD coil and electronic distributor don't need this protection and so can take a higher current and send it to the plugs which allows you to run a wider gap or fire a plug in a high compression engine.
These are just examples and it's a little more complex than this but I'd be lying to pretend that I fully understand it all.  I'm sure one of the electric guys will chime in with a better explanation but this is a start.

myk

Looks like you and I have the same setup then, so I can remove my ballast resistor.  How do you set up the wiring then?  Do you just cut off and splice together the wires that would normally connect on to the resistor terminals?  Actually, one of those wires, a blue one I believe, is by itself, so where would it be spliced into? 
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Ghoste

I'll find the wiring diagram I used from MSD and post it for you.

Nacho-RT74

Venezuelan RT 74 400 4bbl, 727, 8.75 3.23 open. Now stroked with 440 crank and 3.55 SG. Here is the History and how is actually: http://www.dodgecharger.com/forum/index.php/topic,7603.0/all.html
http://www.dodgecharger.com/forum/index.php/topic,25060.0.html

Ghoste

There you go.  Beats the hell out of finding the diagram, scanning it, reducing it to size, and posting it too.  :2thumbs:

Nacho-RT74

Venezuelan RT 74 400 4bbl, 727, 8.75 3.23 open. Now stroked with 440 crank and 3.55 SG. Here is the History and how is actually: http://www.dodgecharger.com/forum/index.php/topic,7603.0/all.html
http://www.dodgecharger.com/forum/index.php/topic,25060.0.html

myk

Thanks guys.  Looks to me like all 3 wires originally going to the resistor, 2 blue and 1 brown, just get spliced together?
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Nacho-RT74

MSD needs to get the signal power on both start and run position. Only way is splice blue and brown wires together since IG switch feeds blue ONLY on Run and brown ONLY on Start.

Take in mind that only a signal source. The MAIN POWER SOURCE to the MSD is the red HEAVY wire that instruction says feed from batt ( or starter relay ) and don't hook to alt stud....

really dunno why  :shruggy:, because on alt stud you will have same power than Batt, plus RIGHT AMMETER charging status reading  ::).

( just making wiring upgrade... stock wires doesn't get the MSD load plus the rest of car normal load )
Venezuelan RT 74 400 4bbl, 727, 8.75 3.23 open. Now stroked with 440 crank and 3.55 SG. Here is the History and how is actually: http://www.dodgecharger.com/forum/index.php/topic,7603.0/all.html
http://www.dodgecharger.com/forum/index.php/topic,25060.0.html

myk

Ok, so just take all 3 wires off of the resistor and splice them together? 
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Nacho-RT74

yes, splice them together with MSD wire to feed the MSD input signal
Venezuelan RT 74 400 4bbl, 727, 8.75 3.23 open. Now stroked with 440 crank and 3.55 SG. Here is the History and how is actually: http://www.dodgecharger.com/forum/index.php/topic,7603.0/all.html
http://www.dodgecharger.com/forum/index.php/topic,25060.0.html