Not sure why you feel the need for electric fans, if you went back to the OEM type setup you would not be having an issue.

One other thing to consider is bumping up your idle speed enough to compensate.

Just two thoughts to consider in the attempt to stay within your requirements.

I have the Powermaster #7508. The tag shows 60a at idle and 99a max. It bolts right into the stock location with the stock wiring.

My contact at PM is Brady Basner. He is very helpfull and you can order it directly thru him. Just tell him that you are looking for as many amps at idle with a stock appearing unit.
bbasner@powermasterperformance.com

I told Brady the same thing and he had the guys build a couple of the 7508's on the floor and he went out and chose the strongest one out of the group and had them ship it to me. Great customer service!!

My headlights do not dim at all in D at a stop. The only accessories that I have beyond stock is two O2 sensor kits and an MSD box. I do not have a high power requirement. This unit is probably overkill for my setup, but it works great at idle and it mounts like the stock unit and it uses the stock wiring.

Brady told me two years ago when I bought my first #7508 that they were working on building their 75a unit into a 100a unit. Then once they had the numbers high enough to call it a 100a unit, then they were going to change the name. My first unit two years ago was rated at 61/90 and this latest unit that I bought in the Spring is rated at 60/99. So you can see they they are slowly getting to the 100a mark.

There's always the factory high amp option... the alternator pictured is from a '78 Cordoba and mounted on a '70E. It uses a re-pop standard engine harness including regulator... with a 6 guage bypass from the alternator stud to fender relay. The ammeter in the OE guage cluster has been converted to a volt meter. You have to look twice and know its there to spot the difference.

On a BB with AC brackets, fitting the later Denso and GM case alternators is a major engineering excercise which is why I went with the later factory setup. Performance, including idle performance is excellent. I switched when the 75A Powermaster just couldn't cut it.

The brackets are OE. I built my engine from a 400 BB core from a '78 Cordoba. The core engine had the brackets and alternator. I cleaned and painted the brackets and swapped the alternator for a reman. I believe the big alternator was used on both heavily optioned SB's and BB's in the mid-late 70's.

The OE wiring on the Cordoba was heavy guage (#6 I believe) to the battery with a shunt style ammeter pickup in the engine compartment. No charge current passed through the bulkhead. The alternator mounts through rubber bushings so it needs a ground wire to the engine block as well which you can pick out in the pic. The factory had learned the bulkhead connector lesson by this point and power level.

Word on the street said powermaster is going to release a 140 amp stock looking alternater comming soon....owner of powermaster said this to my best friend to tell me...

Ok guys so I installed the 100 amp hi performance alternator and still the same thing.

If the car idles with fans for more than 10 or 15 minutes, the car dies. Funny thing is, I can still crank it (starter turns over) but she will not fire until I hook the battery to a charger and top it off. At this "drained point" before I charge the battery, it still reads ~12.8V.

This is so wierd. I am wondering now if my battery is going south? I went ahead and jumpered with 12 gauge wire from the alternator stud to the starter relay (bypassing ammeter) just to see if there is any change. Ammeter obviously doesn't work much but car still cuts off after 10-15 minutes.

And the wierd thing is, the alternator reads 13+ volts when it dies??? Wouldn't this be enough to still keep the ignition working? It's not like I am falling to 12 V here...

This has me confused. Need opinions, bad battery, bad alternator, or just not enough alternator output here?

Seems that I drove the car for about 50 miles off and on with the stock alternator (60 amp) and fans. This car stalling issue reared its head when I added the lights at night. Seems to be getting worse despite the fact that my alternators are getting better!

Ideas??? Please

What is the idle amp rating of that new 100a unit?

Note: the PM units will be 150 & 200 a units with one wire hookup is what I was told this week. That is all of the details that PM would share.

""Would a lose (poorly grounded) VR exhibit the behavior I'm seeing?""

They always say to run an extra ground to the VR to make sure it is grounded properly or it will not sense correctly.
Nice job on the find. Good luck on the startup and let us know what you find.

The "souped up" square backs are not the best at idle... but it sounds like you have something else going on also. I would expect the car to run with 10-11 volts easy let alone 12-13.

Perhaps you have a weak connection somewhere between the ignition switch and coil or ECU. Suggest you check voltage at the coil and compare with battery and alternator stud voltage. Coil voltage should be close to battery voltage (no more than 1/2 volt less) and with the stock setup, no more than 1 volt less than alternator stud voltgage. With the bypass installed, alternator stud and battery voltage should be within a few 10's. If differences are higher, check additional points until you find the problem. Its also possible your ignition control module or coil is "going south"... especially if voltages check good.

A good ground to the VR can only help... but may not be your main problem.

Missing or loose ground will most certainly cause issues and can damage the regulator as well. Make sure the regulator and alt grounds are good....and LOSE THE AMMETER! Also BYPASS THE BULKHEAD CONNECTION! And heres why. Mopes are notoroious for burning the ammeter wires at the firewall bulkhead. Problem stems from either loose connection or corrosion or both and the result is the terminal overheats and can melt the wire as well as the bulkhead plastic! Worst case is a fire! MY bulkhead terminal was melted and that was BEFORE I upgraded from 46 to 60 amps. The bulkhead and ammeter are now both bypassed.

You start beefing up from 60a to 100a and you're askin for a world of hurt if you don't do BOTH the ammeter and bulkhead bypass! I'd also replace that old regulator plug with its hard rubber and 40 year old wires inside. Wouldn't hurt to replace all the wires involved. Voltage sensing and the field wires as well. Splice the regulator plug wires in with a nice western union splice (google it) then solder the splice. Heat the wire and let it suck the solder in for the best splice. You'll need a soldering GUN and rosin core solder. A soldering iron likely won't be hot enough. Cover the soldered splice with heat shrink tubing and Don't forget to slide the heat shrink tubing on BEFORE you splice the wires together!

If you do replace the field and sensing wires I'd upgrade a gauge or two to 14 or even 12. GOOD weathertight crimp connectors are ok if used properly because you're only talking 5-10 amps or so through the alternator field wiring. Maybe a little more for higher amp alternators. Crimped will work but SOLDERED IS BETTER!

Here's a replacement regulator plug from Autozone for 11 bux.
Mopar electronic regulator replacement plug


BTW I can't answer for the DENSO alternator conversion...but the mitsubishi style (withOUT internal regulator) WILL work on a big block with modifications to the lower bracket or just fab up a new one. You'd also need to get a dual pulley to replace the serpentine pulley. I put my mitsubishi eclipse alt on my 66 Coronet when I was testing it. The eclipse pully is serpentine and i had the Dodge V belt running on it so it was slipping (and driving me nuts bcus when I loaded it up the thing would lose voltage and I thought it was an alt or regulator issue! Then after days of testing I FINALLY realized the v belt was slipping on the serpentine pully enough to cause a 3v drop under load!! The Dodge lower alt bracket would NOT work with the mitsu alternator so I pulled up on it and held it tight against the alternator to maintain belt tension as the car was running and that solved the voltage loss mystery. I used a standard VR733 /VR125 style electronic voltage regulator (which is A type circuit) since it's the same regulator I use in my eclipse. I bypassed the regulator in the eclipse computer years ago. I also tested the alternator using my (B circuit) 66 Coronet regulator (which was a replacement type and has the newer electronic guts). Some minor rewiring involved in testing 2 different style regulators but both worked. For electronic ignition or computers though you have to use the A style circuit regulator (VR733/VR125 etc 71 up style) as it provides a more stable voltage output. The mitsu alternator would work fine as a permanent setup if it had a 2 groove V belt pulley and a modified lower bracket or even a slightly different style alternator. I just had the one to play with. If you look closely you can see the alternator lower bolt is just sitting on the lower pulley because the alt front case ribs bulge out far enough to prevent the lower bracket from lining up with the mounting hole in the alternator. I might do the conversion one day and make it permanent. For now...that alternator is back in the Eclipse and the 60 amp squareback back home in the Dodge.

Info overload yet? LOL!

Back to YOUR immediate issue and some possible quick checks! Have you examined the belt condition and tightness? I'm guessing you have since you've already changed the alternator at least once. That slipping belt I experienced in my Eclipse to Coronet alt test was costing me 2-3 volts at idle when I loaded it down...yet idle voltage was normal at around 14.3v! Make sure you're tightening the belt to get about 1/2" belt deflection on either side.

Double check the alt and regulator grounds and test for continuity with a multimeter. Also make sure you have a good ground from the negative batt wire to the engine AND a separate one to the body!!

Check the regulator ground CAREFULLY! Especially if its painted....OR zinc plated!

The VR125 regulator I'm using on my eclipse (same regulator type you have) is zinc plated and it got extremely dull to the point that when I tried to take a continuity reading with my ohm meter just on the surface of the metal I got nothing! The battery wasn't charging properly and I thought I had a bad alternator or regulator. I sanded the dull zinc coat off the regulator shell until it was shiny and then painted it black leaving 2 mounting holes bare with no paint. I attached 2 shiny new screws through the regulator mounting holes to the firewall. I also slipped a a ring connector over one of the screws before securing it and ran a 14ga wire from the connector to my intake manifold so it's grounded at 2 locations. After tightening the regulator to firewall screws I covered them and the eyelet with some battery corrosion spray to prevent further corrosion. Some aftermarket regulators are painted and don't get a good ground requiring a little paint to be scrapped off at the bolt hole. Others are zinc coated and dull out like mine did leading to a bad ground.

HOPEFULLY something I've suggested helps. Either way ... if you're going to the 100 amp alt i'd DEFINITELY Bypass the ammeter and the Bulkhead connection and run a wire right through it....if for no other reason than FIRE PREVENTION!! Just remove the brass terminals from inside the plug and the bulkhead and run a new wire through it. Going up a gauge wouldn't hurt either! If the wire won't squeeze through the bulkhead you can either drill it larger (which may not be pretty) OR run a wire through the firewall with a grommet to protect it or run the wire through an existing grommet like speedometer or something. Just so its not rubbing against a sharp metal edge. USE solder type terminal connectors where needed and SOLDER the wires where spliced since you're talking about the main power for all your accessories! Wire twist and tape alone WON'T cut it! The proper way is Splice, SOLDER and Heatshrink! If you want to add tape for a factory appearance OVER the heatshrink...that's fine.

Good luck.....

Below....Pic of my 440 with the mitsubishi eclipse 120amp alt mounted for test purposes.

Wow! Thanks for the help guys! This is very good information.

I finally drove the car after grounding the VR and she died after about 15 minutes.

However, I had my multimater with me and did some testing roadside and find the issue was actaully ignition!

That's right...Mopar's ECU strikes again. I went and got the $20 cheapy box and it fired right up! Charging looks great and car runs again. I haven't had the time to drive it a lot but the fact that I could crank the car without letting it completely cool is a win!

FWIW I borrowed a good set of clamp gauges and measured the current going to the various loads on my setup:

choke: 1 amp
marker lights/headlights: 13-16 amps
fans: 20 amps
windshield wiper motor 3sp: 6-7 amps
coil (motor off): 4 amps

Seems that now, the alternator I have in there can about break even at a 750-800 RPM idle with the fans on and lights. I will try to do more testing with the clamp gauges when I can get ahold of them in a few weeks.

I also did notice a draw, that I could not pinpoint. With the key in the run position, I get a 5 amp draw from the battery....key turned off...no draw at all. This is with no lights on, coil and choke disconnected. Nothing inside the car (gauges) are connected. What would do this? Is this normal?? Would a bad ECU draw current doing nothing?

Thanks again for all the help here guys! I hope you may have learned something as well here! I know why many people here keep a spare ECU in the glovebox now!

Here is a link to some High Output Alternators, they go up to 320Amps

There is also a calculator on their site so you will know pretty much how big of an alternator you will need. I just calculated mine and it is saying 189Amps at Peak. So I guess I will think about ordering the 200amp model.

http://www.qualitypowerauto.com/catalog.php?category=1