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Alternator Recommendations

msommer001

Full Member
Joined
Jan 15, 2009
Messages
399
1977 bronco, 302, stock all the way around.

I want to replace my alternator. I believe that the stock one is currently installed. I am planning to complete the heater blower and motor upgrade. Everything else will remain stock. I think 65 to 75 amps will take care of the power needed.
 

bronconut73

Bronco Guru
Joined
Aug 7, 2012
Messages
9,918
AutoZone has'm.
65 amp.

I went with a 3G. Got 130 amps and no need for an external regulator.
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
If you're not planning any additional load, the 65 amp factory optional alternator is all you'll need. Anything larger and you'll need to eliminate your ammeter.
 

sykanr0ng

Bronco Guru
Joined
Aug 11, 2014
Messages
5,363
The standard replacement is 65 amp.
Even the truck heater blower motor will not draw more than the 65 amp alternator can handle.

If you were planning on adding more then a bigger alternator would be a good idea, but for what you have in mind you are good with 65 amp.

The original was 42 amp.
 
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OP
msommer001

msommer001

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Got it, thanks for the information.


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904Bronco

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Sep 28, 2004
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San Martin, CA
You could install a small case 3G for 90 amps...

When installing a larger output alt and V-belts, you might have belt squeal at start up...
 
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msommer001

msommer001

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You could install a small case 3G for 90 amps...



When installing a larger output alt and V-belts, you might have belt squeal at start up...



Do you have a part number?


Sent from my iPhone using Tapatalk
 

patterdale

Bronco Guru
Joined
May 24, 2010
Messages
1,247
The stock wiring is not really capable of handling more than the stock alternator. As stated, you will have to eliminate the amp meter. Smoke can and will ocurr when you ask more of the system than it is capable of delivering. The entire load goes through the wire to the amp meter. Google wire size/capacity. That will help you decide.
 
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msommer001

msommer001

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Jan 15, 2009
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The stock wiring is not really capable of handling more than the stock alternator. As stated, you will have to eliminate the amp meter. Smoke can and will ocurr when you ask more of the system than it is capable of delivering. The entire load goes through the wire to the amp meter. Google wire size/capacity. That will help you decide.



How do I eliminate the amp meter?


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904Bronco

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sykanr0ng

Bronco Guru
Joined
Aug 11, 2014
Messages
5,363
For your stated needs the standard replacement 65 amp alternator will work well and you don't need to remove the ammeter to use it.
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
I use the small case 3g alternator 90 amp units came in v6 Ford Aerostar vans and Taurus.
 
Last edited:

blubuckaroo

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Jun 11, 2007
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Loc.
Ridgefield WA
This looks like my best option, is there a part number for the alternator?


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This is a case where you really need to use your head...
Sure you can go to one of the higher amperage alternators without any wiring mods. However, whenever the battery is low, you could have enough current flow to burn up your wiring.
But why do that if you have no other loads planned??:?
 
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msommer001

msommer001

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Jan 15, 2009
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399
This is a case where you really need to use your head...

Sure you can go to one of the higher amperage alternators without any wiring mods. However, whenever the battery is low, you could have enough current flow to burn up your wiring.

But why do that if you have no other loads planned??:?



I live in Nebraska and will need lights, heater, wipers, blinkers all while it is 20 below zero.


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jckkys

Bronco Guru
Joined
Mar 15, 2012
Messages
5,213
I've run a 1G large case 100A with no more changes to the wiring, than the fact that I kept the alternator to regulator harness. This was done to keep the side terminal plug. The voltage regulator is the transistorized type from the same '87 police car as the alternator and looks identical to the OE '77 Bronco one. I run 2 alternator belts so there's no start up squealing. After about 20 yrs. with this set up I can safely say the OE wiring and ammeter work as well as ever. Nothing over heats. So I have to question why anyone would want to delete the OE ammeter? I know the needle pins out with high amp draw but that has never been a problem and only occurs with a nearly dead battery.
 

DirtDonk

Contributor
Bronco Guru
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Nov 3, 2003
Messages
49,236
I would agree with that jckkys, but with caution to others.
I would prefer to keep it too, but all the books and charts say that this is too much current to pass through 10 feet or so of 10ga wiring for more than just a few moments with any safety factor. In some cases they say it's WAY more.
Granted that's probably with a large safety margin and they have to CTA's whenever recommending something, but I take those to heart too when upgrading. Especially when we don't know the overall condition of someone's 40-50 year old wiring.

Otherwise, I'm totally on board with a 100 amp 1G and it's what I use on my full-size (different wiring scheme from the factory though), with the lower output 70 amp model on my stock EB wiring.

Just trying to play it overly safe with the wiring belonging to others here is all.
Full speed ahead and the heck with my own!
I actually plan to use a 130 amp Explorer alternator with my new wiring, and upgrade to 8ga to run through the stock ammeter. Just not sure I would recommend that to others until I've lived with it.
Your 20 year experience with the 100 amp is interesting though. I'd guess you always had wiring and batteries in good shape too? The very first total re-wire I did was because a 120 amp GM upgrade melted the stock charge wiring on a '69. Less than a minute after the first startup in the morning and the entire harness went up in smoke.
Hence my usual caution...

Paul
 

Timmy390

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Jan 1, 2011
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5,747
Loc.
Conway, AR
I actually plan to use a 130 amp Explorer alternator with my new wiring, and upgrade to 8ga to run through the stock ammeter. Just not sure I would recommend that to others until I've lived with it.

When I rewire I was thinking of doing the same......Let us know how that works out........

Currently running a G3 130 amp off a 96 E350 van. Using an aftermarket volt gauge.

Tim
 
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