It seems the general populous thinks that alternators are supposed to put out full power at idle. I've never thought that to be the case.

I haven't found one yet that will make max amps at idle unless the idle RPM is above 1500 RPM
When Mopar introduced the alternator to all there OEM made car sin 1962 with mechanical voltage regulators that wouldn't charge at night with the lights on if the RPM where below 1000 RPM they decided to fixed that 9 yrs. later in 1971 with the solid state electronic regulators and two wire alternators that still wouldn't make many amps at low RPM

actually 70, althought some C bodies began to get elec regulators at the end of 69 production as far I read somewhere

69 Imperial had the first electronic regulator. Temperature at the regulator changes voltage, colder higher voltage and warm lower voltage.

Then why does my 65 Cuda, with a mechanical regulator, not have a dim lights at idle problem?

What RPM does your motor idle at night with the lights on?
Alll the early(pre 1970) Mopars I've owned and driven would discharge with the lights on if the idle was lower than around 800 RPM

Lots of possibilites.
Could have a good matching rotor and stator.
Could have good connections so there's minimal losses.
Might be using points ignition so minimal power draw.
Might be using the original headlamps, nominaly rated 40Watt low beam, or the typical Halogen replacements that are only 35 Watt low beam.

I don't know, but sounds good.

yes!
That's why I thought it was worth posting those output vs rpm curves.

Thing that I have debating since many years ago as many of you know, but ppl never gets it really. Then say I'm crazy and blah blah blah.

Most of ppl think a 100 amps output alt will burn everything then I ask them... how your battery able to provide 150 amps cracking power or so isn't able to burn anything around and is able to light up your 5 watts dome light without burn the bulb or any wiring installation, or even the ammeter ? no answer to this LOL, because they don't understand and never accept the load is demanded by the devices and not simply sourced by itself from the source ( batt or alt ).


if your car load demand is 35 amps, you can fit bigger capacity battery and alt output, the car demand won't change and will be still 35 amps and sources will provide just that. The deal is get sources able to give that. Stock 60s and 70s alts rated at 40 or 50 amps are able to provide around 25 amps iddling, so the battery will be sucked out slowly ( discharge reading ). When revving up, the alt will be able to source that demand and even get back the charge to the batt ( Charge reading ) but just while RPMs are enough. That constant ammeter swing is what get stressed the charging system:

Bulkhead conectors, specially black wire alt one could hold the 35 amps load from the regular load demand, but if batt is discharged giving the 10 amps the alt wasn't able to source at iddle, the alt will feed maybe the stock 50 amps at certain RPMs A discharged batt will become on a one more sucker device when discharged just like headlights could be. This makes this bulkhead terminal drives 35 amps for the car load plus the 15 amps getting back to the batt, Too much for the Packard terminal. 35 amps will be kept to feed the main splice and 15 amps will be running up to batt through the ammeter, which after year of unbalanced system, unnecesary stress causing heat, loosing everything becomes on the major failure we all know, but is not ammeter fail by itself, is the unbalanced system from factory.

To add an extra failure, electrical upgrades being sourced from batt or starter relay post. This will translate as a battery sucking power, so MORE stress to the ammeter making a "ghost" or false reading like charging.

Althought hard to beat, the ammeter is not a unbeatable gauge. Still needs attention and care. It could be built more resistant from factory but for whatever reason they weren't. IMHO the main failure on the ammeter design is get press in studs to the internal shunt ( brass, really sensible to heat ) that with constant loads could began to get contact failures causing heat, stretching parts being increased with years loosen the studs pressure from the shunt. If they were solded from the begining, nothing was happened. So this detail added to the unbalanced charging system produced all the myths and fears about the ammeter system

I got the bigger pulley in and installed yesterday. Made a big difference. I can live with the results so far. At idle with the lights on it is putting out 13.5-13.6. I can handle that. as soon as you touch the gas now it jumps up to 14.5 and stays.

it is pretty stock, right down to the factory pulleys on the alternator and crank. It is an AC car so it does have a high capacity alternator.