Alternator Upgrade?
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Record Breaker
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From: Va
Alternator Upgrade?
I have a 87 dakota V6 with a 78 amp alternator. I have added 2 electric fans, in place of the mechanical fan...... They pull about 16.5 amps each. I am setting them up to run first stage, (1 Fan) second stage (2 fans).
Now to my point, Truck seems to be charging at 14.3 volts with engine around 1000-1500 rpms?
But when the AC is on, both fans running, Im reading 12 volts at the battery, idleing the motor.....
It appears, rockauto offers a 120 amp double pulley alternator. I suspect this would be enough.
Would I need to change wiring other the the battery feed to the alternator?
Also, with a pulley change, would this alternator mount to a magnum engine accessory drive? I plan to eventually put a 5.9 in the truck, but will not be using the magnum FI system, so the regulator will stay external.
One last question, are there any good 1 wire conversions I should consider?
Thanks
Now to my point, Truck seems to be charging at 14.3 volts with engine around 1000-1500 rpms?
But when the AC is on, both fans running, Im reading 12 volts at the battery, idleing the motor.....
It appears, rockauto offers a 120 amp double pulley alternator. I suspect this would be enough.
Would I need to change wiring other the the battery feed to the alternator?
Also, with a pulley change, would this alternator mount to a magnum engine accessory drive? I plan to eventually put a 5.9 in the truck, but will not be using the magnum FI system, so the regulator will stay external.
One last question, are there any good 1 wire conversions I should consider?
Thanks
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Record Breaker
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From: Va
Not sure.....
When I look at the FSM they show a 78 amp external regulator....
Then they list 50/120 amp alternator with voltage regulator in engine electronics....
I assume the 78 amp was on the V6 as it had a carb.....
50/120 was on the 4 cyl? but again, I assume.
FWIW mine was a late model (april 87)
Back on track, when looking at rockauto, they only show 2 for the V6 90amp or 120 amp.
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Record Breaker
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From: Va
I got to figure out what the big 3 is..... The battery cables, I swapped to heavier ones a few years ago.
The 120 is what I will probably end up doing,
Do you know if it will mount on the magnum accessory drive, and be able to switch the pulleys to the serpentine style?
It would be nice to be able to reuse the alternator on the magnum if I am able to swap motors this winter.
BTW it will not have the dodge computer when I swap. Planning a holley 670 street avenger carb. (I already have) and an electronic ignition....
Champion
Joined: Jan 2013
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From: Northwest Louisiana
I got to figure out what the big 3 is..... The battery cables, I swapped to heavier ones a few years ago.
The 120 is what I will probably end up doing,
Do you know if it will mount on the magnum accessory drive, and be able to switch the pulleys to the serpentine style?
It would be nice to be able to reuse the alternator on the magnum if I am able to swap motors this winter.
BTW it will not have the dodge computer when I swap. Planning a holley 670 street avenger carb. (I already have) and an electronic ignition....
Here's from an email I got from them (sale price may not be in effect anymore):
we offer
240amps $359, sale $299
300amps $459, sale $399
powdercoat $45
Lifetime Warranty
to order, we send invoice to your email,
you can pay with any card or paypal
240amps $359, sale $299
300amps $459, sale $399
powdercoat $45
Lifetime Warranty
to order, we send invoice to your email,
you can pay with any card or paypal
I landed there looking for something better than a 105A for my wife's 1991 Cougar.
RwP
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From: Clayton MI
3.9 V-6 right? Same engine/bracketry that was used on the full-sized trucks?? Get an alternator for a full-sized truck. 
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Record Breaker
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From: Va
I did look at that..... Basically showing the same for both full size and dakota. But thanks
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Record Breaker
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From: Va
Hey Ralph,
I "think" the big 3 you were talking about is basically upgrading the postive cable, negative cable, associated grounds, and the alt. feed to a larger size... Is this correct?
I cant find a listing in my FSM showing ga. size of the cables....
Assuming I can use the 120 amp alternator, would you mind answering the following questions?
1. What size neg. cable to battery?
2. What size pos. cable to battery?
3. What size feed from alternator? I believe you already said, "at least a 4ga. on that one"
FWIW, I believe I can get the 120 amp through advance auto for about $80.00.... but another concern is, the 120 used an external fan vs the 78 using an internal fan.... Hopefully it will mount up, and the pulleys will align...
I "think" the big 3 you were talking about is basically upgrading the postive cable, negative cable, associated grounds, and the alt. feed to a larger size... Is this correct?
I cant find a listing in my FSM showing ga. size of the cables....
Assuming I can use the 120 amp alternator, would you mind answering the following questions?
1. What size neg. cable to battery?
2. What size pos. cable to battery?
3. What size feed from alternator? I believe you already said, "at least a 4ga. on that one"
FWIW, I believe I can get the 120 amp through advance auto for about $80.00.... but another concern is, the 120 used an external fan vs the 78 using an internal fan.... Hopefully it will mount up, and the pulleys will align...
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