No Chrome Alternator for me either.

First of all, thanks to all of you that contribute and help out the rest of us with these kind of issues with our cars. That being said:
I had bought a chrome alternator this past weekend at Stafford Spring's swap meet. $10 bucks was too hard to pass up.
I promptly installed it, started the car and watched my ammeter charging at idle for the first time. Measured voltage at the battery at idle was 13.2.
At @ 1100 rpm the ammeter needle was pegged! Measured voltage at 1100 rpm was 18.1........
The regulator is (was) the mechanical points type. It blew in about 5 minutes.
I had a spare solid state for a pre 70' that connected just like the original and lasted twice as long as the first.....10 minutes.
This got me into reading every post I could find on this subject here at FABO and started some fear of fire feelings with my 44 year old Barracuda's wiring.
I have seen other posts where some have had the same issue with overvoltage and it seems to stem from these 85+amp alts.
Although I realize the stock ammeter was designed to see much lower amps (Does anyone know exactly what range the stock one is good for?)
I cannot for the life of me get the alt to NOT produce 18 volts at anything above 1100 rpm and pegging my ammeter.
I have bought the newer style 70and up regulator, wired it up and get the same high readings.
Threw the little 35 amp (guessing)jobbie back in with the new regulator and all is well except still not charging as well as I would like at idle....12.5. But 13.8 at 1100......

Mike

Stock alternator was probably around 45 amps. I've never seen a replacement electronic regulator that looks like the stock mechanical regulator that was rated for more than 65 amps.

This alternator you bought probably has a partially shorted field. That is, some windings inside the field are rubbed, burned, etc, shorted together, and the field is drawing too much current.

ALL Chrysler regulators should work on pretty much any alternator. I've used early Chrysler units on older Delcos, and in fact have one on my Oliver crawler regulating a Toyota alternator.

I used to run one of the "big frame" late '70's Chrysler OEM 100+ amp units on my old Landcruiser, and I used a regular Chrysler '70 and later regulator on it.

I agree with 67Dart273 and therefore disagree with '64 Cuda. I don't think the regulator knows anything about the current output of the alternator. It senses voltage, not current flow. The old mechanical ones are an on-off control. The electronic ones are proportional, i.e. the lower the battery voltage they sense, the more field current they apply.

A bigger problem with the higher output alternators is that you can fry your ammeter in the dash and associated wiring connections. That is a bad day. There are some solutions posted to bypass it or install a voltmeter in its place (like later cars). I am thinking of a designing a bypass circuit that lets it still work, but protects it from overload. Someday.

I recall the original alternators are spec'd as 30A, but as Cudaroy says, actual output depends on engine speed. I recall J.C. Whitney used to have upgrade kits where you replace the field coils to give ~60A output.

BillGrissom said:

I don't think the regulator knows anything about the current output of the alternator.

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Correct. All it knows/cares about is the current draw of the alternator field circuit. This is dependent on the windings of the rotor in the alternator. Early alternators (through about '80 or so) had field current draw of about 2.7A. Later ('81-up or so) had field current draw of about 4.4A. Years and current specs I give here are approximate; my spec books are far away at the moment. The changeover was done well after the 1970 change from electromechanical regulator controlling the feed side of the field circuit with one field wire connected to one isolated alternator brush (and the other brush grounded) to electronic regulator controlling the ground side of the field circuit with two field wires (and both brushes isolated). Early electronic regulators aren't rated for the higher amperage of the later rotors and so are not forward compatible; you'll burn out an early regulator using it with a late rotor. Later regulators are backward compatible since they are rated for the higher-amp rotors—though with today's fine made-in-China "quality", all bets are off. As for regulators compatible with the pre-1970 single-wire system that will also handle a high-current rotor: NAPA Echlin VR-1001 or Standard-BlueStreak VR-128.

A bigger problem with the higher output alternators is that you can fry your ammeter in the dash and associated wiring connections. That is a bad day.

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Yes. See here (including links) and here.

I recall the original alternators are spec'd as 30A

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The early A-bodies had standard original alternator output ratings of between 27A and 35A depending on year and equipment; 40A was the optional heavy-duty item. Output climbed over the years as equipment levels and electrical demand increased; the highest output alternators installed on regular production A-bodies was 65A, starting in '73 when equipped with the heated-grid backglass defogger (and available as an optional extra without the defogger).

J.C. Whitney used to have upgrade kits where you replace the field coils to give ~60A output.

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Alternators do not have field coils; generators and starters do. Alternators have rotors and stators. Those JC Witless kits included a replacement stator. Yes, you get higher max output, but at the expense of low-RPM output, which is already a weak point of the Mopar alternators.

BillGrissom said:

I agree with 67Dart273 and therefore disagree with '64 Cuda. I don't think the regulator knows anything about the current output of the alternator. It senses voltage, not current flow.

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I was just going by what the sellers of the regulators say. The regulators are supposed to work with alternators with outputs up to 65 amps.

I was wrong. '64 cuda was correct that some electronic regulators could not handle the current draw of later alternators, per slantsixdan. However, not because of alternator output current, but rather from the higher current draw of the field (>3A). However, there is probably one-to-one mapping, so a rule like >70A output alternator will kill an early electronic regulator probably works.

Re knowing your alternator's output rating, I am going out on a limb, but think the early round frame ones were all <45A, unless they had a J.C. Whitney upgrade kit (how could you know?). The later square-back ones (ca 1980's) were ~70A I recall. slantsixdan's suggestion to get the later electronic regulator should work for any alternator.

The roundback grounded-field (or "single field") alternator came from the factory in variants ranging from 27A to 60A. The one-year-only '69 Imperial roundback alternator for use with a 3-pin electronic regulator came in one rating only, 60A. The '70-'71 roundback isolated-field alternator for use with a 2-pin electronic regulator came in ratings from 30A to 60A. The squareback ('72+) isolated-field alternator for use with the 2-pin electronic regulator came in variants ranging from 46A to 78A.

I wouldn't go putting down all chrome alternators,mine has worked just fine for 4+ years...what did you expect from a $10 swap meet alternator??...

stroked 340 said:

I wouldn't go putting down all chrome alternators,mine has worked just fine for 4+ years...what did you expect from a $10 swap meet alternator??...

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Thing is stroked........there is nothing wrong with the alt......even for $10. It was with the associated components I.E. Ammeter,regulator,wiring that I was having issues with and thanks to this site helped me understand why it wasn't working in MY car. Glad all is well with yours......