Electronic distributor leads reversed?

[Montclaire]

Will an engine run with the distributor leads reversed? I’m dealing with a hacked harness and the factory one-way distributor plug is gone. What happens if the leads are reversed? The car runs but doesn’t want to rev, although that could be due to a faulty distributor. Any easy way to identify which is which? Thanks

 

[bearman]

Which dizzy do you have.

 

[Montclaire]

Factory mid 70s electronic

 

[WP29440SE]

I had mine reversed when wiring in an HEI and it would not fire until I had them correct.

 

[bearman]

Do you have a red and black wire coming out of the dizzy. Red should be power and black ground. If you have a test light use it and it will tell you which is ground and the other would be power.

 

[Montclaire]

They are both black. I think the leads off the harness are brown and brown or blue with a tracer.

 

[Nacho-RT74]

Once on a hacked harness I had reversed the distributor wires on engine harness. Engine started on, but missing beats.

 

[Montclaire]

I have a new distributor on the way, hopefully the internals are color coded.

 

[66Satellite47]

I have a stock plug & a wiring diagram for the DC electronic conversion. The stock plug has grey w/black tracer that goes to the male plug connector on the distrib (red or orange on my DC distrib) and plug has a brown/w/black tracer to the female plug from distrib which is black. Hope that helps.

 

[RJRENTON]

IMO....
IF the distributor is question is Mopar's Electronic unit, then polarity is important. The distributors pick up coil generates a positive going pulse each time a reluctor tooth passes by. This positive going pulse ttiggers the ECU (control box with the external transistor), to turn off allowing the coil to generate the spark pluse. IF the distributor's pick up coil's polarity were reversed (wires reversed) a negative going pulse would be generated. The ECU would recognize a change of state and may or may not trigger the coil to produce a spark...or...if it does, it may be erratic and produce intermittent coil trigger pulses. The ECU needs a consistent trigger pulse train of the correct polarity to function accurately and repeatedly. Rather than buy a new fidtributor, why not just reverse the trigger coil's leads and see what happens? Just my opinion of course.
BOB RENTON

 

[Montclaire]

Bob, the distributor that's on the engine now is in rough shape (internally and externally) and should be swapped out anyway. If I thought it would have been worth spending some time cleaning it up I would have gone that route. I should have a spare plug off an old harness around here somewhere and will wire it up correctly when the new unit arrives. I'm chasing other gremlins as well so it's just easier to eliminate any issues with the old distributor which was on its way out anyway.

 

[RJRENTON]

Bob, the distributor that's on the engine now is in rough shape (internally and externally) and should be swapped out anyway. If I thought it would have been worth spending some time cleaning it up I would have gone that route. I should have a spare plug off an old harness around here somewhere and will wire it up correctly when the new unit arrives. I'm chasing other gremlins as well so it's just easier to eliminate any issues with the old distributor which was on its way out anyway.

I understand....not realizing the condition of the existing distributor. The new distributor MAY have an adjustable vacuum diaphragm assembly and MAY need to be tailored to your application. The adjustment is accessible thru the vacuum advance fitting on the advance chamber with a small allen wrench. This adjustment changes the internal spring tension to change the RATE of advance not the total amount. Also, you MAY need to check the mechanical advance rate and amount to suit your application. Let us know if we can help furthur.
BOB RENTON

 

[Montclaire]

Update, I actually had an old distributor in my parts stash that I had forgotten about. That has been happening to me more often these days. Anyways I gave it a quick once-over and a few drops of oil and threw it in. Since it still has the factory plug all I had to figure out was the other end. 66Sat’s diagram was right on the money and it’s wired correctly now. I turned the key and she bumped right over and will actually rev now so all’s good. Thanks again to everyone.

Now, the newer MP distributors I believe have Mallory guts in them and I know they definitely have the adjustable vac advance. There was a good article by Mopar Action on these a few years ago that went in-depth on fine tuning them with a spring kit for the mechanical advance. The springs are still available but I believe they are part of a larger kit. If I find the issue I’ll post the volume number. I need to dig it out anyway to tune the MP distributor for the 440 in my 64.