HEI Conversion wiring question

[Duster_71]

Hello All,

I know, not another hei tread, I could not gain a clear picture from some of the post I found.

Working on a 74 Duster and trying to set up a ready-to-run hei distributor. I was getting ready to splice the brown and dk blue wire at the resistor and started to get confused. Once I splice these wires together am I good or do I need to run a lead to the (+) of the coil from the splice. I was under the impression that splicing the brn and dk blue wire would eliminate the resistor and icu and everything would be good. Then I started reading post that didn't come out and say you needed to run a lead to the coil but it sure sounded like it.

v/r
Ron

 

[Mopar Tim]

If you connect the two ends that went to the ballast resistor, you will have full voltage to the ignition. Just use the same wire that used to go to the coil. Now you will have full voltage all the time there., well with key on at least.

 

[Duster_71]

If you connect the two ends that went to the ballast resistor, you will have full voltage to the ignition. Just use the same wire that used to go to the coil. Now you will have full voltage all the time there., well with key on at least.

My 74 service manual schematic shows the brn wire going to the (+) coil, guess that where I get confused, thanks.

 

[67Dart273]

Yes you can splice the brown and blue, "why you need them"

The dark blue is "ignition run" or IGN1 and is hot ONLY in "run," it loses power during "start."............

Which is why you need the brown, the resistor bypass circuit. It is the ONLY wire (for ignition) that is hot during cranking.

I don't use a resistor with HEI Even with a stock Mopar coil

 

[kiss]

ok first im drunk as **** right now
second is this
throw ballast resistor int he trash
use both brown and blue wyre togehter. 1 is hot @ start 1 is hot @ run
problem solved problem staying solved, rangers lead the way!
[search "action figure therapy" on youtube and thank me later]

 

[Duster_71]

Thanks for the responses, so, I will not have to run a lead to the coil because the brn already goes to the coil, just splice the brn and dk blue? What about the ground if I eliminate the icu?

 

[TrailBeast]

Thanks for the responses, so, I will not have to run a lead to the coil because the brn already goes to the coil, just splice the brn and dk blue? What about the ground if I eliminate the icu?

The only ground needed at that point will be the distributor negative to the coil negative.
Then you can get rid of that 15 feet of original ignition box wires.
I just clipped them all right where they came out of the harness and retaped the harness.
Sorry to butt into the conversation, but you asked real early and I figured you would like the answer early so you could close it up today.

 

[67Dart273]

................

 

[KitCarlson]

The only ground needed at that point will be the distributor negative to the coil negative.

Then you can get rid of that 15 feet of original ignition box wires.

Not trying to be picky, but correct. That distributor negative is not "ground", it is often black wire, but all black wires are not ground. The body of the distributor needs ground. Best to add ground wire from distributor screw to intake. When distributor clamp is loose for adjusting timing, ground can become intermittent, it can stress the HEI module. The distributor black wire does connect to coil negative, but no ground connection at that point.

About getting rid of 15' of wire, care must be taken not to cut or open IGN circuit to voltage regulator, or no charge problem may result.

 

[Duster_71]

OK, what about the voltage regulator and charging system, does any of the wires from the ICU do anything with the voltage regulator?

 

[67Dart273]

OK, what about the voltage regulator and charging system, does any of the wires from the ICU do anything with the voltage regulator?

At some point, might be the ballast, the dark blue "run" splits off and feeds several circuits. BEAR IN MIND this is not fused, so don't get sloppy.

Depending on year/ model, dark blue or "ignition run" feeds ballast to coil +
ECU power
VR power
light blue ends up at alternator field
electric choke if used
some smog doo dads on some years

I would carefully cut open the harness and pull the ECU wiring out

 

[TrailBeast]

Not trying to be picky, but correct. That distributor negative is not "ground", it is often black wire, but all black wires are not ground. The body of the distributor needs ground. Best to add ground wire from distributor screw to intake. When distributor clamp is loose for adjusting timing, ground can become intermittent, it can stress the HEI module. The distributor black wire does connect to coil negative, but no ground connection at that point.

About getting rid of 15' of wire, care must be taken not to cut or open IGN circuit to voltage regulator, or no charge problem may result.

I guess I should have been more clear about the wiring.
What I meant was the part of the harness that used to go to the Mopar ignition box can all be clipped at the harness on the engine side of the firewall.
Thanks Kit.

 

[Duster_71]

At some point, might be the ballast, the dark blue "run" splits off and feeds several circuits. BEAR IN MIND this is not fused, so don't get sloppy.

Depending on year/ model, dark blue or "ignition run" feeds ballast to coil +
ECU power
VR power
light blue ends up at alternator field
electric choke if used
some smog doo dads on some years

I would carefully cut open the harness and pull the ECU wiring out

Thanks 67Dart273, what happens if you cut the light blue out? If you eliminate the ICU how would you or what would you link the light blue to? Again, thanks.

v/r
Ron

 

[67Dart273]

Everything I listed earlier, if still used, needs to be tied/ spliced to the dark blue "run" The light blue branches off that at some point........might be at the ballast.....and goes to the alternator field

"Pretty much" everything at the ballast needs to be tied together. If you do that, the old coil + wire becomes straight 12V and can be still used to the coil/ branch to the ignition. Only thing "comes out" is what directly leads to the ECU

 

[TrailBeast]

See if this helps.
The first picture is the Mopar basic ignition and charging system.
You will see all three wires (Ign1, Ign2 and the blue voltage regulator wires connected where Mopar put them.)

The second pic shows what you want to do. (just ignore the green arrows, as well as the text at the bottom of pic 1)

At the ballast Ign1, Ign2 and the blue regulator wire all get tied together and the brown wire of the three can still go to the coil +.
The red wire for your new distributor gets connected to the three so it gets 12v and the black wire on your new distributor gets connected to your coil -.

 

[BillGrissom]

If your engine bay wires are sound, I wouldn't snip anything. You can get a male-male spade connector to simply plug the 2 ballast resistor connectors together, or you can make a similar short jumper wire. If brittle wiring, I would strip out to simplify and replace bad wires (best to use same colors and gage). If some guy did above and didn't get +12 V switched power to the coil, they probably had a goofy brown wire (IGN2) or didn't do above correctly. Post photos. You wouldn't believe the shoddy work some guys show after pages of "didn't work" fussing. Our ridicule may be coarse, but will be helpful. Some guys think that twisting wires and wrapping w/ electrical tape is good-enough.