Ecu and ballast resistor questions

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74dustertwister

74dustertwister

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On my 1974 duster 360, i recently upgraded to a HEI distributor as well as installed an American autowire wiring harness. Its been great, i love the new harness, however it lacks information about a ballast resistor and ECU. The distributor is a 2 wire, (battery and tach). Like i said, there's nothing to indicate a need for the ECU on the diagrams AAW provides but im just not sure. Im not too good at wiring, this might be a rather simple question for some of you. Do i just forget about it or do i need to splice the ECU in somewhere? And what about the ballast resistor? Id prefer to bypass as much as i can if possible. im hoping to clean things up a bit for a few shows and competitions. Any help and advice is much appreciated
 
I believe the short answer is no (Chrysler) ECU with HEI based on my reading.
No real world experience in HEI.
You WILL get a better answer from the group.:)
I think you will need to provide more info on your distributor though.
I just wrestled the ignition alligator and went the other route.
 
20170513_131051.jpg
 
I believe it depends on the type of pick-up/trigger assembly that your distributor uses. Most HEI's would have an inductive type pick-up that would not require a resistor. If it happens to have another type, photocell for example, then it may need a resistor for it's protection.
 
65wgn440 said:
I believe it depends on the type of pick-up/trigger assembly that your distributor uses. Most HEI's would have an inductive type pick-up that would not require a resistor. If it happens to have another type, photocell for example, then it may need a resistor for it's protection.
Click to expand...
How could i go upon checking this?
 
Check manufacturer's info for your distributor or remove cap&rotor to get a visual on pick-up, then compare to pics of different types of pick-up's, I guess. A stock Chrysler electronic is an example of inductive/ magnetic type. A photo-cell type would usually use a rotor with "windows" cut into it.
 
74dustertwister said:
View attachment 1715048392
Click to expand...

That distributor does not require any ballast or ECU.
The ECU and coil are a matched set and both are inside the distributor, and "ready to run" as is.
All it requires is power to it in the "Start" and "Run" positions both of the key, so you need to find those two wires, connect them together and power your distributor with them.
They both used to go to the ballast resistor, so finding them isn't hard using a test light and they should be right where the ballast used to be unless they were cut off by someone.
 
TrailBeast said:
That distributor does not require any ballast or ECU.
The ECU and coil are a matched set and both are inside the distributor, and "ready to run" as is.
All it requires is power to it in the "Start" and "Run" positions both of the key, so you need to find those two wires, connect them together and power your distributor with them.
They both used to go to the ballast resistor, so finding them isn't hard using a test light and they should be right where the ballast used to be unless they were cut off by someone.
Click to expand...
Awesome! On that new harness, it is set up to run HEI out of the box.
 
65wgn440 said:
I believe it depends on the type of pick-up/trigger assembly that your distributor uses. Most HEI's would have an inductive type pick-up that would not require a resistor. If it happens to have another type, photocell for example, then it may need a resistor for it's protection.
Click to expand...

Sorry no. Nothing to do with the pickup device

The resistor is a function of the design of the coil and the switching device driving the coil. Part of the reason resisters have ever been used was the coversion from 6 to 12V. By BYPASSING the resistor during starting, in the cold or with a low battery, the lower starting voltage would still provide a hot start with the resistor bypassed. That is only part of the reason.
 
Wow, this is rather complicated. All very interesting though, i enjoy learning about this. So with the setup i have, am i free to run without an ECU or ballast resistor? And i see now the difference between the magnetic setup and the photoreceptor set up, that's really interesting.
 
GM HEI = no resistor. Many of us run Mopar distributor driving a GM HEI module. The short answer is you need to jumper the IGN1 and IGN2 together, usually brown and dark blue. This is because the IGN1 "run" goes dead when turned to "start."
 
67Dart273 said:
GM HEI = no resistor. Many of us run Mopar distributor driving a GM HEI module. The short answer is you need to jumper the IGN1 and IGN2 together, usually brown and dark blue. This is because the IGN1 "run" goes dead when turned to "start."
Click to expand...
that would make sense. However, Would this be the case with my new wiring harness? Its set up for an HEI platform. Ill send a picture of the diagram i have when i get a chance. I keep running from school to home, ill get a good chance to examine my notes and original wiring diagram tonight.
 
Aftermarket harness?

Here's the thing........it's the original OEM Mopar IGNITION SWITCH which causes this. All these switches have two IGN posts. One is the "run" but is only hot in "run." It goes dead in start. The IGN2 (brown bypass) is hot in start. It is a separate poste and contact from the yellow "start" circuit. If your harness does include the IGN2 wire, you need to tie the two tgether at the switch itself
 
67Dart273 said:
Aftermarket harness?

Here's the thing........it's the original OEM Mopar IGNITION SWITCH which causes this. All these switches have two IGN posts. One is the "run" but is only hot in "run." It goes dead in start. The IGN2 (brown bypass) is hot in start. It is a separate poste and contact from the yellow "start" circuit. If your harness does include the IGN2 wire, you need to tie the two tgether at the switch itself
Click to expand...

That would work just as well as doing it under the hood, probably cleaner.
Thanks Del.
I guess if the harness was made for HEI or similar it may have been wired for constant hot on a single wire anyway.
We'll see when he posts the diagram.
 
That's a poor diagram, but looks like (7) and (3A) is what you want Check with a test light/ meter.
 
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