Alternator wiring question

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Viper21700

Viper21700

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Ok geniuses.
Here goes. Was out warming the car up tonight (I got bored, wanted a smoke, and really had the urge to hear her run for a while.. yes I know its cold as heck... sue me lol) and while planning my replacement wiring for the voltage regulator I noticed something odd.
The alternator is a two field wire alt (1+ 1- lead) but instead of running the - wire back to the voltage regulator (some off brand, no name, 1 wire electronic regulator) the previous owner just made a jumper wire from the negative terminal to a ground on the alternator.... Now Im thinking to myself something isn't right here, but it seems to work.
Anyone want to chime in and tell me if I should go ahead and replace the alt when I rewire the two wire voltage regulator (doing a late 60's style conversion, using the factory style triangular plug 68-70 electronic regulators)
Just something that didn't seem quite right when I saw it and figured you guys would have some input.
 
Viper21700 said:
replace the alt when I rewire the two wire voltage regulator (doing a late 60's style conversion, using the factory style triangular plug 68-70 electronic regulators
Click to expand...

You post made sense until this last

Chrysler used what amounts to the same regulator from the very first alternator (60--whatever) up THROUGH 1969

They look something like this:

$_35.JPG


Now MOST of these that you buy in parts stores nowadays are actually electronic. To tell, look at the bottom. If the cover is about half original height or less, it's electronic. If it's full size, and there are NO resistors on the bottom, it's electronic

If it has two large wirewould resistors on the bottom, it is "mechanical." The two interchange.

NOW your original 60--69 alternator only had ONE insulated brush. This means you can use a LATER alternator (1970 / later) by grounding one brush and hooking it up just as if it was original, and that sounds like what it is that you have presently.
 
Since you already HAVE a 70/ later alternator --properly called "isolated field" and often IMproperly called "dual field" you can add just one more wire and install the 70 / later regulator which looks like this:

312-P3690731.jpg


If you wander over to the tech page at MyMopar, there are several bits of interest on wiring the old/ new system

http://www.mymopar.com/index.php?pid=31

Essentially the only change is the added blue wire to the what was previously grounded field wire. Where the old regulator FEEDS current to the alternator field and controls that current, the new style rather controls the "amount of ground" via the green wire

Dual_Field_Alternator_Wiring.jpg
 
Thanks dart,
I was mistaken on my year of the voltage regulator. I didn't realize that you could run the newer style alternators like that which is what was throwing me screwy. Ive already grabbed the wiring harness for the isolated field setup I snagged out of an older dodge p/u at the local pick and pull last week.
 
I am kind of confused also. If the junkyard engine harness has a triangle voltage regulator it was probably a 70-85 truck.

If interested in how the current system was working, a photo of the Vreg (you will toss) would help. It was probably using the "high-side switching" method of 60-69 Mopars. Vreg applies +12 V periodically to one field terminal (high side) and the other terminal is grounded. Ford & GM probably did similar. Those used a mechanical relay that turned on and off, but as 273 said new ones are often solid-state and proportional (no switching). Measure the voltage drop across the field terminals. The Vreg should adjust that from 12 V (full output) to 0 V (no output), whether it uses high-side or low-side (triangle Vreg) control.
 
Ill try to snag a pic when it warms up a bit. we got close to ten inches of snow last night and the car is buried in the parking lot right now lol.
 
Not to old of a post.
Just replying to say thanks.
I did a search and found exactly what I was looking for here.
Just wanted to confirm what I was thinking.
I was guessing that it would be an "electronic" "one wire" voltage regulator from a parts store. Now I know what to look for.
I'm planning to use that regulator with a spare "two wire" alternator from my 70's cars in a 69. Could run an extra wire but won't look as 69ish.
Should work, huh?
 
Yup. Just ground the extra field terminal. I've beat this to death, but be sure you actually get the thing grounded "same as battery" and check it with a meter

Also check your harness voltage drop, because drop EITHER in the ground circuit or the hot side of the harness will ADD to charging voltage.

Easy to do

Engine running "fast," battery up and normal, check with all accessories off, then again with heater, lights, etc on

Stab one meter probe onto the battery NEG terminal, and the other onto the regulator mounting flange.

You are hoping for a very low voltage, the lower the better, and zero is perfect

On the "hot side," Turn the engine off, turn the key to "run." Hook your meter to the IGN terminal of the regulator and battery POS post. If you see more than .3V (three tenths of a volt) you need to investigate where you are losing this
 
Yes sir.
Thanks for the tip. Had not considered looking for a difference in potential at those points.
I like it when I don't have to think about things.

Going a off topic, just because you are watching.
My "driver" is giving me fits. 318 cop engine, Q-jet. All "stock" stuff.
This is the car that I think I sent someone a flaky orange box to do a post mortem on. That box was causing a rough idle but good at RPMs above idle.

The car has just developed a "mis" at low RPM under load. Not rough, but a "mis". Like it's shutting off for a micro second.
Does it under under load and acceration to a point. Then clear.
I opened and checked the carb.
I even swapped on spare Q jet today and have looked for VAC leaks. VAC is steady. 20 at free idle. 15 in gear.
So I'm thinking somthing in the igniton. But a timing light flashes good and I've looked at the wires in the dark to find arcing. Nothing seems off.
The mis gets worse as the car is driven. Hotter. Maybe the ballast (single) resistor.
I'll post when I find out.
Tomorrow when I have all day, I'll start swapping parts, change wires and get new plugs
(I've found Autolite AP 66 run best in my 318 setups. The ones in this car may be 7 years old or better.)
 
That was probably "me" you sent that two. Unfortunately, I did not find anything definitive. I ended up using my pressure washer to try and remove some of the potting (it was adhered to the board) and either one of the paper capacitors was already damaged, or the pressure washer finished it off. "A couple of those" boxes (aftermarket) the potting came right out. Not so this one.
 
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