I upgraded the underhood wiring of my 65 Barracuda with that from a 72 Swinger back in the late-1980s to gain an electronic ignition and charging system. In terms of idle power output, I haven't found the Dart's dual field alternator to be any improvement over the single field alternator. I also changed to a Carter electric fuel pump back then (thought I had fuel delivery issues at the drags), which made the idle charging situation a bit worse. The electric fuel pump likely keeps me from having any hot restart problems now though. At idle, my voltmeter is around 12V and often fluctuates in the 10-12V range with the lights on.

Now that I'm driving my car regularly again, I find that the low idle voltage is a bit annoying. I see from earlier alternator discussions, one of the best alternator upgrades is to use a Nippondenso 40/90 with v-belt pulleys from '89-'91 Dodge trucks and vans plus '89 M-bodies. From a quick search on Rock Auto, I found 1988 Fifth Avenue as also having a ND alternator. The higher output of the Denso alternator would mean that I'd also have some rewiring to do to avoid frying my ammeter.

The only upgrades I'm planning on that would add to the power demand are AM/FM stereo, HEI ignition, and electric radiator fan. I also have a rear window defogger fan. I think I can easily power everything from the 100 Amp alternator in my 78 New Yorker parts car but this would still mean some rewiring and probably bracket modifications. Has anyone adapted a 100 Amp alternator to 30 Amp alternator bracket?

Pre-1989 Chrysler alternators would drop-in and would likely be cheaper than the Denso alternators. Would a 60 or 65 Amp Chrysler alternator be able to keep up with the electrical load on my car at idle?

In the topic New Old Parts Source, Dan mentions 78 Amp alternators. Would this be a finned or square-back type?

Pre-1989 alternators won't get you where you want to be. "Finned or squareback" doesn't make sense; all of the Chrysler alternators through '88 have finned housings; that includes the '60-'71 "roundback" and both designs of the '72-up "squareback". Ray at OCPNW has squareback units. None of these alternators does a good job at idle and low RPM; if you want decent low-RPM charging use an '89-up Chrysler, Bosch, or (preferably) Nippondenso 40/90 unit.

The bracket mod isn't difficult; you need to shave 1/8" off the lower bracket's tubular part where the alternator's lower bolt goes through, and you need to either notch and bend the upper slider bracket so it looks like this:

__________
/
/

Or use an '88-'91 318 upper bracket with its bolt-type tension adjustor

Or use one of those universal chrome straight-and-then-curved slider brackets.

I have a set of brackets to mount the giant '70s 100A alternator on a slant-6. It will not fit in an A-body. It will also not fit on the smaller alternator brackets (hits the head).

Whatever big-amp alternator you pick, you're looking at charging system wiring upgrades of one sort or another; they were marginally adequate for a 30A alternator.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks for the quick reply. I was going by the descriptions I came across in earlier postings and thought "finned" referred to the smaller 30-65 Amp alternators while "square-back" referred to the larger 100 Amp style ones.

The earlier discussions seemed to indicate that the 60 and 65 Amp alternators had a lot more output at lower RPMs to run heavy draws like the rear window defroster. It wasn't clear how well they worked at idle though. I had my doubts that my spare 100 A unit would fit.

I was hoping that I might be able to do a quick alternator upgrade over the summer but it looks like it might be more of a winter project.

AR Engineering used to offer a bracket setup to mount a Delco (or probably numerous other mount-compatible) alternator on the manifold side of the slant-6. I don't see it on their newly redesigned site; probably worth an email to see if they still offer it on a make-to-order basis.

Sometime in the late '70s or early '80s the small-housing ("squareback") alternator got a higher-draw rotor which made low-RPM output less inadequate, and there were versions up to 78A, but really, none of these has good low-RPM output. It remained a weakness of this alternator design right through to the end. Some of them are better than others, but none of them is really good; the stator winding pitch is way too loose and the rotor-to-stator clearance is way too great.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Andy sold all his slant 6 related stuff to me a couple years back, there just wasn't enough demand for any of it. I have 1 complete metal pattern for the driver's side alternator mount-both the motor bracket and the curved upper bracket, and the cads for the /6 to LA adaptor plate, along with one motor/tranny carriage setup (bolt it to your new combo and roll it around the shop...)

Currently I get one or two asks for this stuff but not enough to make a production run (cost alwasy outweighs everyone's budget), and I don't want to be out a big chunk of change waiting to sell all of them either.

FYI,

-D.Idiot

Would the A100 van alternator mount work with the 89 - up
or Denso alternator upgrade?

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65 Dart station wagon slant 6 - now under construction
47 Dodge Custom 4 Door sedan
87 D100 Short Bed slant 6

Retired USAF 1966-1986
Retired US Postal Service 2004-2014

Of all the practical things I have done to my car while putting it back together, one of the best things I did was move the alternator to the drivers side. It just makes the P.S. a much more pleasant place to work.
I also moved the coil.

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6