All other things being equal, which 100 amp alternator is “better” for an upgrade? I found two vans at the junkyard: one with a nippondenso v belt alt and the other with the huge Chrysler 100 amp alt. Both have all the brackets, so I could go with either unit. Which would be the “better” choice?

T'were me, I'd go with the Nippon. It does give you the problem of finding or fabricating a v-belt pulley for it, but you end up with a more modern power source that will typically have an output at lower rpm's than the big Leece-Neville unit.
I'm running a small, 65-amp Nippon on my slant-powered T, and haven't had a problem. That's having been modified with a single v-groove pulley and self-exciting internal regulator.

Roger

I second the Nippon. Have it on all my slants. Just remember if putting on a earlier vehicle to upgrade the wiring.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

We need a test! And maybe to know which unit has better parts availability. I saved a 100 amp Chrysler alternator from a 1978 Magnum I parted out. It ended up as part of a generator project. If you full-field the alternator is will nearly stall 4hp diesel which drives it.

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Joshua

Hmmmm. Well, this is what I am doing. I am hoping to upgrade the charging system as part of an AC system upgrade on the 1982 Ramcharger I got recently. The motor is a 318 so the AC compressor brackets and the alternator bracket are closely related.

The charging system currently is mostly stock, but the prior owner wired in a second battery using a battery isolator. The second battery was for an electric winch. I have removed the winch but my brother has installed an aftermarket stereo and used the former winch battery for an aftermarket stereo. I am having a problem with the current charging system where the alternator belt slips badly. I know the belt is tight but it also is a belt that is at least 12 years old that sat for a long time outside with the motor not running. The batteries are known good batteries, but I suspect the alternator is having to put out almost a full load at idle which makes it harder to turn which makes the belt slip.

I might grab the brackets and huge alternator and also grab the denso alternator since it already has a double pulley. I believe the water pump and crank pulleys are the same for either alternator, and the AC compressor bracket for the huge Mopar alternator is actually a separate piece from the alternator bracket, so I can use the current stock brakcet to mount the Denso alternator if I choose to go that route.

OK, back to the junkyard I go.

It looks like it is going to be the honking Mopar alternator for now. I didn't have all the toolsI needed yesterday to get all the brackets, so i left when there were ten minutes beforte the junkyard closed. I got there this moring one hour after they opened. When I left yesterday, the Denso alternator was still there. When I got back this morning the Denso was GONE. Someone had snuck and and taken it out from under me. So I will have to try the huge old Mopar alternator, for now.

These old Mopar 117 amp alts are HUGE. I will have to post a comparison picture of the 117 amp, a standard Mopar alt, and Denso alt. Hard to believe that the dinky Denso alternators put out as many or more amps as the big old Mopar alternator.

Given the choice my vote would've been for the Nippondenso, but my vote's for the one you've got. Parts availability is about the same. The Nippondenso is smaller, lighter, and more efficient (and they get even smaller, even lighter, and even more efficient than that—the later Nippondenso units, such as the 136A items installed on turbocharged PT Cruisers and such).

Make sure you run a voltage regulator that will handle the high field current draw of the alternator you're installing (suggest a genuine Mopar unit from OCPNW), and put in a field-load relay—see here—if you haven't already got one. No need to worry about the ammeter; it's an external-shunt type and either won't care or already doesn't work.

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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 Dan! This will be a somewhat long term project. I just wanted to grab all the parts because I happened to find a vehicle that had everything I needed. I almost got the Mopar voltage regulator on the parts can I got the alternator frim. I should have. I will get a NOS unit instead.

I won’t be installing these parts until later in 2018 (hopefully) when I start the AC installation. Finding the correct AC compressor brackets for a Sanden compressor is what started this project. It just happens that the donor vehicle also had the huge Mopar alternator. I still need to piece together the rest of the AC system, so I will have plenty of time to gather the best parts and wiring to make the charging system safe and reliable.

I will be doing these same upgrades on my 76 D100 (upgrading charging system, installing AC) so I will be doing lots of research to get this all correct. The 76 is slabt powered, though, so it will definitely be getting a Denso alternator.

OCPNW also has a ton of those giant Mopar 100-117A alternators, brand new on shelf (or at least they did last time I was in there).

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

So I need a 3755 850 voltage regulator, NOS highly preferred. I found one on eBay through OCPNW! Looks like he finally got online.

But can you tell me more about the field-load relay? Do you have a part number? I read the link and it sounds like a good thing to have. There appears to be very limited info about it online. I believe it looks like a regular voltage regulator but wires in between the regulator and battery. Does that sound right?

You don't need a particular, specific special field loads relay, just an ordinary good-quality 12v NO SPST relay will do just fine—the kind I go swimming in all day, every day for headlamp relay kits. Terminals are trigger +, trigger -, load in, and load out. Hook it up as per the diagram.

3755 850 is only one of several Mopar regulators that'll do the job correctly. 4111 990 is another. 4379 100 is another.

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

OK- let me reach back into the dusty cobwebs of my high school electronics class memories. I need a good quality 12 volt normally open songle pole, single throw relay, such as is found in headlamp kits.

Load in is the field wire FROM the voltage regulator? Load out is the field wire TO the battery? Trigger + is a switched battery feed and trigger - is solenoid post on starter relay?

Alternatively, on the relay

Terminal 30 = feed from voltage regulator
Terminal 85 = connects to the solenoid terminal on the starter relay
Terminal 86 = connects to the "start" circuit on the ignition switch
Terminal 87 = feed to battery

Does that sound right?

I already ordered a 3755 850, so that is what I will go with. It cost only slightly more than the Chinese knockoffs currently on the market.

This ought to enlighten.

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

It does! Thanks again Dan!