Mods made by P.O. What do I have with this engine bay harness?

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DusterDaddy

DusterDaddy

sledgehammer mechanic
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74 Duster Under hood harness has only one field wire plus main alternator wire.
The is no triangular shaped 2 pin voltage regulator connector on the harness either. It does have 2, 2 wire plugs near the red seatbelt interlock connector.

The car was a basket case when I got it and the engine harness was thrown in the back seat.

Does this sound like a known mod or upgrade?

I'd just as soon bring it all back to use the 2 field wires on the alternator and the standard Mopar regulator.

Not doing the MAD upgrade and will be using the stock ammeter.

Will most likely use hei ignition hidden in an old hollowed out Chrysler ignition box with the ballast resistor modified so it is just a pass thru at full 12 volts.

IMG_5906.JPG
 
It sounds like it's possible the PO used an aftermarket one wire alternator and removed the regulator from the system.
That would have been an internally regulated alternator.
It's also possible it had a Mopar single field alternator, but that would not explain the regulator plug missing.

In any case you could use a dual field alternator and add the regulator since they are easy to wire up.
 
TrailBeast said:
It sounds like it's possible the PO used an aftermarket one wire alternator and removed the regulator from the system.
That would have been an internally regulated alternator.
It's also possible it had a Mopar single field alternator, but that would not explain the regulator plug missing.

In any case you could use a dual field alternator and add the regulator since they are easy to wire up.
Click to expand...

Thanks TrailBeast. Wondering what you would do?

I'm thinking since I have the two field alternator and both field wires are in the harness (one with its spade cut off) and I bought a new Mopar regulator, I'll buy a regulator plug and put it back the way it should be.
 
DusterDaddy said:
Thanks TrailBeast. Wondering what you would do?

I'm thinking since I have the two field alternator and both field wires are in the harness (one with its spade cut off) and I bought a new Mopar regulator, I'll buy a regulator plug and put it back the way it should be.
Click to expand...

Sounds totally reasonable to me.
If the harness is basically out right now and you already know where you will want the regulator you can wrap new regulator wires up with the rest of the harness and put terminals on them where you need later when you see how they route best and all.
The OE regulator wiring was a blue wire that connected to the"ign on" circuit to sense voltage and the other (brown I think) went to the alternator field terminal. (Regulator case must be grounded)
 
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TrailBeast said:
Sounds totally reasonable to me.
If the harness is basically out right now and you already know where you will want the regulator you can wrap new regulator wires up with the rest of the harness and put terminals on them where you need later when you see how they route best and all.
The OE regulator wiring was a blue wire that connected to the"ign on" circuit to sense voltage and the other (brown I think) went to the alternator field terminal. (Regulator case must be grounded)
Click to expand...

Going to do my best to find out where all the "boxes" were supposed to go and put everything were it's supposed to be.

Also thinking I'll eliminate the multi pin connector that branches off to the engine harness and solder and heat shrink those connections

My bay does not have a piece of wire in it yet....
 
I recall seeing the triangle Vreg plugs for sale, probably rockauto. In my early A's, I mounted the later Vreg on the inner fender near the alternator. That keeps the wiring simple and obvious. But, sounds like you want a factory look. Others have wired a GM 4-pin HEI module inside a hollowed-out Mopar ECU case. Just insure it gets good thermal contact to the case, using thermal grease, and it also needs a good ground. The engine harnesses are usually brittle so need major re-work. All under-dash wires in my cars were like new, other than hacks by gomers which I fixed.
 
Everything I see shows this being the correct layout with a brace to the inner fender from the booster bracket and the ignition box behind the washer tank on 74 Dusters.
I'm pretty sure I see the attaching holes still in the fender where they were on your car.

1974%20Plymouth%20Duster%20Engine%20Bay.jpg
 
TrailBeast said:
Everything I see shows this being the correct layout with a brace to the inner fender from the booster bracket and the ignition box behind the washer tank on 74 Dusters.
I'm pretty sure I see the attaching holes still in the fender where they were on your car.

View attachment 1715008398
Click to expand...

Thanks this pic is so helpful. What is the tin canister between the washer bottle and the ballast resistor? And is the regulator attached to it? I found one in one of the boxes of crap that was in the trunk when I bought the car. But can't find it now
 
BillGrissom said:
I recall seeing the triangle Vreg plugs for sale, probably rockauto. In my early A's, I mounted the later Vreg on the inner fender near the alternator. That keeps the wiring simple and obvious. But, sounds like you want a factory look. Others have wired a GM 4-pin HEI module inside a hollowed-out Mopar ECU case. Just insure it gets good thermal contact to the case, using thermal grease, and it also needs a good ground. The engine harnesses are usually brittle so need major re-work. All under-dash wires in my cars were like new, other than hacks by gomers which I fixed.
Click to expand...
The condition of the wire and the connections both inside and under hood are very very good on my car, just some quick fix it butchery here and there. Nothing that can't be fixed with a soldering iron and heat shrink...
 
DusterDaddy said:
Thanks this pic is so helpful. What is the tin canister between the washer bottle and the ballast resistor? And is the regulator attached to it? I found one in one of the boxes of crap that was in the trunk when I bought the car. But can't find it now
Click to expand...

That silver device on the verticle section of the fender IS the regulator, and the ignition box is right behind the washer tank laying flat.
It's been a few years now, but my 73 Dart had exactly the same layout when I got it as the picture I posted.
 
TrailBeast said:
That silver device on the verticle section of the fender IS the regulator, and the ignition box is right behind the washer tank laying flat.
It's been a few years now, but my 73 Dart had exactly the same layout when I got it as the picture I posted.
Click to expand...
Thanks again. The vreg I just bought looks like this. Made in China, BWD branded

IMG_5921.JPG
 
TrailBeast said:
That's the right part application wise.
Click to expand...
One more question if I may. When doing the HEI conversion in a 74, I assume when bypassing The ballast resistor, you bypass the main and the auxiliary resistors (top and bottom)
Thanks
 
DusterDaddy said:
One more question if I may. When doing the HEI conversion in a 74, I assume when bypassing The ballast resistor, you bypass the main and the auxiliary resistors (top and bottom)
Thanks
Click to expand...

Yes, because you would be doing away with the OE ignition box and coil both so no more need to reduce voltage to anything.
 
The only existing holes that the replacement vreg line up with put it here
IMG_5936.JPG

Judging from the blue 74 above (which is exactly the look I'm going for) the vreg was mounted on what looks like a 8" long tin box that was bolted to the verticle part of the inner fender below the fender bolts. The holes can be seen here
IMG_5938.JPG


I'm pretty sure the ignition box goes where the vreg is sitting now. I am waiting for a used ignition box to ship to me that I'll hollow out to hide the HEI module. Once it's here I can see if it matches up with the holes.

The only place the starter relay lines up with existing holes is here. Kind of close to the battery tray, but I thinks this is right.
IMG_5937.JPG
 
The regulator will not fit on the verticle innerfender as pictured in the blue 74. Could always trim the mounting tab a bit if this is where it's supposed to go
IMG_5939.JPG
 
While my harness is not altered, it is tough to tell what was actualy plugged in on any particular car. They made a lot of changes 73-75 with emissions junk. Here is mine. This is a LATE 75. Disregard the hose up across the starter relay, my squirters were not hooked up in that pic. Also on passenger side there is a white plug near AC drier. That was an emissions thing I am still trying to determine if it would have be used on my car.

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Next a couple pics of other cars from Carlisle. I believe these were both 74. The red one shows the regulator where mine is and also one of the magic emissions boxes on the firewall. I think this one is an EGR dalay timer IIRC. The brown car shows what I believe is a start cutout on the inner fender behind the washer bucket. You would have had this with your seatbelt interlock. I don't have a good pic from the other side of his bay, but I believe his regulator is in a different location. This car belongs to a FABO member, Booker? I think?

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Awesome Keith! Thanks so much. I permanently bypassed the seatbelt interlock. I'll put the vreg, ignition box and ballast in their intended locations as yours are.
thanks again!
 
DusterDaddy said:
Awesome Keith! Thanks so much. I permanently bypassed the seatbelt interlock. I'll put the vreg, ignition box and ballast in their intended locations as yours are.
thanks again!
Click to expand...
Since you are not trying to make everything original, that will work, but as said.. Your regulator may not have been there. Also, your start relay may have been elsewhere, ( below the flange of the cowl I believe) Just curious, What is the build date on your car (driver door sticker)? I have been trying to figure out when they changed the bumpers. You had absorbers on back, but not front, correct? Did yours have the large square looking gaurds front and back?
 
zkx14 said:
Since you are not trying to make everything original, that will work, but as said.. Your regulator may not have been there. Also, your start relay may have been elsewhere, ( below the flange of the cowl I believe) Just curious, What is the build date on your car (driver door sticker)? I have been trying to figure out when they changed the bumpers. You had absorbers on back, but not front, correct? Did yours have the large square looking gaurds front and back?
Click to expand...
I'll look for build date sticker.
Mine had bumper shocks only in the rear and the bumper guards in front and back.
 
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I was able to get a cheap ignition box at autozone. Need to fool around with cutting and heat the get the innerds out.
 
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