The Dodge Challenger Message Board

I posted this question on the site before so appologize for asking again. I've been struggling with this issue for 5 months and seem to be getting nowhere. Here it is.......I have two ballast resistors in my engine bay, a four post and a two post. The four post is wired correctly but the two post is missing one of the wires. Before I broke the car down for restoration I took pictures of everything and it looks like one of the wires comes off the positive side of the coil and runs to the left side of the two post resistor. However, I can't locate where the right side of the ballast resistor wire comes from (right if the bolt holding to the resistor to the fire wall is on top of the resistor) because it was obstructed when I snaped the picture. Could it be possible that the right wire comes off the negative side of the coil?

I've looked at wiring diagrams for months and just cant figure it out. Actually, every diagram I've seen only shows one ballast resistor in the engine bay, the four post. It's possible the two post was added aftermarket.

If anyone can help it really would put an end to this never ending frustration.

Thanks!

Take the extra resistor and bin it. If you want a factory appearance keep the 4 spade one, if you want simplicity and ease of operation use a 2 spade one in accordance with Mopar Performance guidelines, I'll see if I can find the link for you, it was posted here not too long ago. I ran a 4 spade for ages on my '72 and then switched to a 2 spade when I installed an FBO ign set up. Works lovely

Use the two spade.

It just needs to be in line with the coil +ve when powered from the "run" wire from the ignition switch.
The wire from the "start" position on the switch goes to the same end as the coil +ve is connected to in in effect when you are cranking the engine you are by-passing the resistor.

The resistor lowers the voltage going to the coil. The stock type coil is designed to run at just under 12 volts so that is fine. But when it is by-passed during cranking you are giving it a but more voltage in theory. In paractice the effort of cranking the engine lowers the voltage in the system so the by-pass is there to make up for that.

Running more than one resistor or too large a resistor will give you a weak spark.

Okay, I think I'm just going to remove the two post and run with the four. I'm not sure why the two post was added but I suspect it was because an after market coil and distributor was added during the cars life and the prior owner felt an additional resistor was needed??? Who knows. I resinstalled an original coil and distributor during the restoration process.....

Thank you both for giving me the perspective I needed to reason this out.....much appreciated!

Check out this link from Fabien, does'nt get any more comprehensive than this
viewtopic.php?f=13&t=8671

You're right....this is what I was looking for. Thank you!

Thanks for finding that thread Adrian.

Adrian Worman wrote:Take the extra resistor and bin it. If you want a factory appearance keep the 4 spade one, if you want simplicity and ease of operation use a 2 spade one in accordance with Mopar Performance guidelines, I'll see if I can find the link for you, it was posted here not too long ago. I ran a 4 spade for ages on my '72 and then switched to a 2 spade when I installed an FBO ign set up. Works lovely

Exactly what I did with my '73.