100 amp alternator

[and00542]

In February's Mopar Action, in the Tech Topics' section, there's a guy that writes in to say he's got a MSD6al, a high voltage Blaster coil, and an electric fan hooked up to his 340. He mentions that the original 35 amp alternator wasn't strong enough to handle to demand, so, he wants to upgrade to a 100 amp alternator.

The tech guy tells him he has to upgrade all his wiring to 10 gauge copper wire, bypass the bulkhead connector in the firewall and upsize the fusible link or else, KABLAMMO! Fire in the hole!

Has anyone done this modification? Is it as much work as it sounds? Should I just keep my MSD and my 35 amp alternator and go to an aluminium radiator (no electric fan)?

[dewme5]

I put an 80something amp alt into my my car, and ran into some expensive rewiring. As far as how hard to do, it's very easy. I would at the same time, get rid of the ammeter if you have one. A voltmeter does a much better job of telling you the condition of your charging system. As for upgrading the fuseable link, I would upgrade right to a fuse. Swing by any car stereo shop in your area, and pick up some 10 or 8 guage wire (about $55 cents a foot), a fuse holder ($5), or a circuit breaker (I have one and love it, but it's about $50) Get a few connectors, and a few hours, you are all set. The other option, is to go with a whole new wiring harness. Painless has an 18 fuse version for about $320, and will make your world much better than dealing with 30 year old wire.!

[ehostler]

take a look in the archieves. There is a good thread about alternator conversions in there.

[MitchB]

When I upgraded the alternator in my 80 aspen, I ran seperate 8-gage wiring directly from the alternator to the battery. I spliced-in a fusable link. This gives two parallel circuits to the battery: the factory wiring and my wiring. Each circuit will carry roughly half of the total current. My car uses a shunt ammeter which carried only part of the total charging current. I left this intact. It still indicates whether the car is charging or not. After ten years, I have had no problems.

Mitch

[dewme5]

I dislike the ammeter, because when somehting goes wrong, you have a huge wire, and 2 open terminals on the back of it. This actually caused all the wiring in my 74 dart to literally explode, and the fuseable link did nothing. All original parts, and all in decent shape. So, I upgraded to the painless kit, and loved it. With a volt meter, if you are putting out 12.5V or less, your alt. isn't charging. if you are putting out 13.3v or more, your alt is charging. just that simple. (if you are in the gray area 12.5-13.3, you probably need to get a new alt. anyway.

[bbeckwith]

So....if Im running an 80 amp in my duster, I should run the extra wire from the alt to the battery, and bypass the ammeter? I have the stock duster instrument panel, what do I need to do with the two leads to the ammeter? I have a spare harness I pulled from a 73 DART that was unmolested by stereo installers and such, but, the hot lead to the ammeter has started to fry, can I just replace this with a larger wire or..?

[340MAN]

Well guy's, I guess you dont know how much drag a 100 amp alternator will have on your engines. That large of unit will be like having a/c unit on.
The Cuda I just sold ran a 340 with factory 3 core radiator, 1 electric fan & electric fuel pump along with MSD 6al. The trick is to put the fan & fuel pump running off the alternator itself. Running these units of the factory electrical system on Mopars is asking for a fire. This way your factory electrical system is not harmed and the power demand is coming straight off the alternator.
The down side is that if you do not have a good alternator you will find out shortly. I put fuses between the alternator & the electrical devices for short protection. I run all my additional electrical devices this way except MSD which are off the battery.
Well this worked for me, it might for you also.

[ehostler]

the horsepower drw of the alt is directly propportional to the amount of load it is having to keep up with. Pushing 20 amps, the 100 Amp alt will not rob anymore horsepower than the 35 amp alt.

I do agree that any electronics added to the vehicle should be powered by the alt/battery leads and not the cars factory electrical system.

As far as wiring in the larger alt goes, just run a second bat feed from the alt to the battery pole, on the starter relay. This should be a minimum of 8 gauge. The alt gauge does not have to be bypassed, in this configuration, however as the alt is feeding both sides of the dash electrics, the guage will be there for looks only.

[bbeckwith]

OK, sounds like the plan then! Thanks again.

[ehostler]

If you do want to bypass the ammeter, just get a bolt that will fit through the terminal leads that are on the back of the gauge. Pull the leads off of the gauge and bolt them together. Then wrap them really well with some electrical tape. The other option (probably a little more safe) is to cut-off the terminal ends and then strip the wire back and splice them together with a good crimp.

In any case, please make sure that you disconnect the battery, before doing anything. That is unless you like to see arcs & sparcs and fires...

[bbeckwith]

Thanks again Ed,
I currently have the motor out along with both front harnesses as I have the engine bay nearly ready to repaint. I will use the extra wire to the alt-battery trick when I put it all back together. I also have a primo Rallye Instrument cluster and Rallye dash shell I want to install but I think I will wait a while after I put the car back together, I am getting itchy to drive it again. I got a spare dash wiring harness I pulled out of a 73 Dart that I thought would be a good replacement to the one I have now. The replacement has never been hacked on, and I think I will have a little more peace of mind using it over the harness I have now. I see numerous splices in it from previous owners for aftermarket gauges and stereos and such. I would buy a new one from year one but that $500 price tag is a bit steep for my taste.

Bruce

[71dart666]

I dont know much about electrical stuff but i got a 65 amp alternator on my /6 Dart and it works fine. I got a 200 watt CD player in it, i can drive with headlights on stereo and windshield whippers going and the defroster before it starts to drain it... even then it only drains at idle. I tried a 100 amp one but it didnt fit... dont know if it was error on the part of the guys at Kregens or what but anyways just thought id comment.

[ehostler]

I'm going with a 130 AMP unit, myself. It only cost $89, after shipping. With that much potential, I know that I will never have dim lights at night, while sitting at a stop light.

[6 packin]

Fact is that mopar made the worst charging system and altenators made, and the best starters made. The local repair shop which he only does starters and altenators. He said that he has made a living off there altenators and, he could die hungry with there starters if he was depending on them. One problem with there alts is there is no fan on the outside like the counter part GM brands. After along time of troubles and charging system wows, I simple bought a 1 wire GM altenator and replaced my inferior Mopar charging system. Even the amp gauge works. This eliminates many problem spots there. Mostly on my street or strip cars this has been done, this is a good swap and I highly recommend it. But no one here likes the thought of a GM part under the hood of there mopar. Fact of the matter is, it really cleans the engine compartment up and gives you way better charging, even when new the Mopar system was not that good. Maybe they spent the extra money from there cheapo charging system and made there gear reduction starters.

[dkn1997]

for those who are considering the 130 amp conversion, there are a couple of things that are not in the original thread. THE FOLLOWING COMES FROM CHARGERDAN WHO ALSO PERFORMED THIS SWAP. IMHO, part I applies to any high amp alt conversion.

I. here is an option for protecting your new charge wire:

Mega-Fuse, 125-amp, Napa p/n 782-1137, cost me $8 at my local auto electric
shop.
Mega-Fuse fuseholder: $28 at Napa, or $9.77 at CarQuest (just ask for
CarQuest p/n 298900).

II. there is a connector on the back of that alt for the field wiring, no luck finding a factory connector, but here is one that fits.

Source: Zilkoski Auto Electric - (541) 747-9213 - ask for Arlen (the guy I
dealt with on this)
Part Number: AF50-12170 "alternator harness"
Manufacturer: Couldn't get them to tell me the manufacturer's name.
All he said was that an auto-electric parts manufacturer up in Portland
(Oregon) makes them.
Zilkoski Price: $10.00 (+ $3.00 shipping) He still has a couple in stock

[charger_dan]

Hey guys,
I'm almost done with my 130A Denso alt. swap.
When finished, I want to take Kevin's (DKN1997) great info.
plus the things I've learned from doing the swap myself,
and wrap it all up in a mini how-to article like you'd find
in a magazine (part #s, sources, installation process, etc.)
Then create a PDF file that I'll make available either here
or directly from me (free of course). Folks can download, print,
and go shopping.

Should make this easy swap even easier.

Dan

[kekoakeakane]

For everyone who would like to know more about how to improve your electrical systems and a good comparison of one-wire vs. 3 wire alternators, check out the Tech Section at M.A.D. Electrical. I've completed the mod to remove my Ammeter from service and upgrade the wire from the alt to a 10 Gauge from the original 12 gauge. That should allow use of up to 100 amp alt. If I were to upgrade to a 140 or 200 amp alt, than a 8 gauge wire would be called for.

To determine what gauge wire is necessary, you need to determine how much power the wire will carry (volt & amps) and how far (feet). Based on these numbers refer to this Wire Capacity Table to figure out which gauge wire you need.

BTW, since my stock fuse box had rusty terminals and used glass tube fuses, I decided to upgrade my fuse box to the 12 circuit painless fuse panel. I'm ultimately going to use the 18 circuit wiring harness, but needed something now and don't have time to rewire the entire car just yet.

[dusterbd]

i was working with painless a little while back trying to get us premade replacement/upgrade harnesses. didnt fly, because they couldnt find the proper factory style terminals or plastic connectors. my question is, with yopu guys that are running painless kits, where did you get the stuff? now that the duster is effectively taking a dirt nap, i can do it right.
please advise
thanks, yall.
mike

[451Mopar]

I would like to convert to a higher amp Denso alternator too, these are small and most can take 14,000+ RPM at the alternator!
The stock Mopar alternators are not very durable on a high RPM engine, and if you run a under drive pulley, it reduces the low RPM output even more.

Wiring is actually pretty easy. I will just run an extra (large) wire in parallel from the alternator output to the battery. Because this wire is larger and lower resistance than the stock wire it will carry more than 1/2 the output current. The stock wiring will still be in place so everything still operates as original (except the ammeter will not be accurate.) The Denso alternator needs the feilds connected like a stock alternator, preferably the newer electronic regulator.

For high draw accessories like fuel pump, lights, etc. run them from the battery or directly from the alternator through a relay.

Adding fuses for saftey, just in case something shorts out.

[dkn1997]

that's the way, 451. such an easy swap, and such a major improvement-that guy on ebay who is selling them for 75 bucks should get a medal......

[451Mopar]

Who is selling them on E-BAy? last time I checked these were selling for $200+ rebuilt, that is why I haven't upgraded yet, but last time I had the car out the charging systen started acting up like the alternators brushes were intermitent.

[dkn1997]

the seller is truckandrvsupply, and he is selling one right now, for the click of a mouse, it can be yours for just $74.00 plus shipping. this is the one chargerdan, eberg from moparmucsle mag, and me used.

http://cgi.ebay.com/ebaymotors/ws/eB...tem=1876019593

he does not have them 100% of the time, but if you look for any two week period, one always pops up

[dkn1997]

forgot, this is a brand new factory alt, the only miles on it are probably the drive from the dealer to the ambulance conversion shop

[bbeckwith]

Hey Kekoakeakane,

Thanks for the link to the MAD Electrical site, it answered all my questions and I learned a lot. A very good site for those of us who are electrically challenged! Now I know exactly what to do with my spare harness I have. Very informative, thanks again.

Bruce

[451Mopar]

Thanks dkn1997@aol.com, I bought it!
I think he had 3 for sale?

What pulley are you using, I was told there is a "v" belt pulley that will bolt on in place of the serpitene pulley?

[ehostler]

451- you just need to swap out that serpantine pulley with one from a GM alt.

I bought the 130 AMP alt myself. I've got it and an old GM alt sitting on my garage floor, just waiting for me to do the conversion.

There is a lot of good info about this conversion at http://www.moparchat.com/forums/show...2&pagenumber=2

[dkn1997]

I used a gm pulley off a 69 camaro, but they are probably all the same from that era (like their cars, bla!) but chargerdan used a mopar pulley- I forget which one. my local electric guy claims that all mopar pulleys are pressed on and will not work with this alt, but I suspect there is a late model mopar pulley that works (bolts on.) ask dan about this if he does not jump in here. the only problem with the gm pulley is that it does not catch to many threads on the alt (only about one shows above the nut) but with some locktite and an impact gun, you should be fine.

[charger_dan]

Here's an image of my Denso alt. with the pulley I'm going to use.
It's brand-new, purchased at my local auto-electric shop for $7.50.
The fella who hooked me up with it said "it's from a late-model Dodge
pickup truck." Despite my urging, he couldn't be any more specific
than that. If you look closely, you can see that thread engagement with
the OEM nut is excellent.

I must say there is ONE trade-off with using this pulley in its stock form:
compared to the GM pulley Kevin is using, this pulley is a bit wider in
the area between the first belt groove and where it mounts to the alter-
nator. What this means is your belt locates about 1/8" farther AWAY
from the alternator when compared with the GM pulley alignment.
So, what does this mean? Well, to maintain proper belt alignment with
stock bracketry/pulleys, you need to mount the alternator 1/8" farther BACK
toward the motor, where things are already a little snug. However, I've
got everything mocked-up on my motor, though, and it should work just fine.

Can't wait to get this puppy running!!!

[charger_dan]

The attached image graphically shows what I explained in the previous
post about pulley/belt spacing with the Dodge pulley. White circles indicate
pulley offset and spacer required to maintain stock belt alignment.
Hope this makes my post clearer...

[dkn1997]

hey dan, I see you left that stock bushing in the rear ear of the alt, did you have to cut down your spacers to fit? by the way, excellent pics, very clear, thanks- Kevin