High-Capacity Alternator

[Aggie Charlie]

Greetings. This is my first post, so here goes....

I have a 1974 Ford Bronco and installed a Ultima 63 AMP Alternator - Part #: R111621A from O'Reilly's. It seems to perform better than the old one, but I am wondering if there is a direct replacement, higher output alternator that would work. I am installing a Dakota Digital Gage set, and was wondering which is the best alternator out there that will work, without any modifications. Thanks in advance!

 

[bigmuddy]

Doesn't completely answer your question but here is an older post on upgrading stock alternators to a high output.
https://classicbroncos.com/forums/threads/76-alternator-3-wire-harness.313873/#post-3415535

 

[bigmuddy]

Oh and welcome to the obsession, lots of good people here at CB.com and are willing to help out. Pictures are frequently necessary when asking questions, but you will need to be a contributor to the site to do so. $12 a year to become a contributor and post pics.
Helps Jon keep the site afloat too.

 

[DirtDonk]

Since something like 65a was about the maximum that you ever found in the small case 1G Alternator design, you would end up with a custom wound aftermarket unit.
Probably out there available up to 100a now, or maybe even 150.
But I’m not sure.

But a standard 1G small case alternator is the only way to get a bolt on with no modifications.
I use the standard 1G large case version in 70 and 100A, but you will have to cut and clip a couple of wires.

And frankly anything over 70A you’re going to want to change the wiring anyway.
I think what you’ve got now is possibly your only option as far as no modifications to your wiring.

 

[Broncobowsher]

No modifications, you are already there. 60A is the upper limit of the small gauge wiring in a stock Bronco harness.

Now if you want a nearly no modification upgrade, something reversible, the small case 90A 3G is pretty good. Direct feed the charge wire to the battery, little tweak to get the turn on wire from the external regulator and moved it to the internal regulator of the 3G. Pulley swap. Change the lock bolt on the adjuster arm over to a metric one. Everything is reversible if you ever want to. No permanent modifications. Why the 90A and not the 130A? Belt squeal. The 130A 3G does exist and often people will just go for the biggest one they can put in there. Think about 90A is still 50% larger than stock at peak and probably double the output at idle. 90A is more load, but just small enough you might get away without having belt squeal issues that you will get running the 130A on a single V-belt. Unless you want to start modifying even more stuff... The charging system generally doesn't make full capacity, just enough to cover running loads and a touch more to top off the battery after a start. Unless you really modified something that uses a lot of electricity even the 90A version is only going to put out a tiny bit while cruising the road.

 

[Aggie Charlie]

Man. Thanks for all of the advice and pointers. I upgraded the Wiring Harness to the CENTECH one, and all seems to be good, wiring wise. I will look at the ones y'all have been outlining. Thanks again for the help!

 

[DirtDonk]

Even though Centech uses essentially the same gauge charge wire (10 gauge), they claim that theirs is good for up to 100 A.
So you can keep that in mind and perhaps upgrade a little more if you decide to.
But just as was said above anytime you go over 70, but absolutely if you go over 100 you need to upgrade the charge wire.

The 95 amp 3G is a worthy update for any bronco. But it is definitely not a “no modification” upgrade.
Your original alternator would’ve been anything from 38 to 55 A rating. And then over time it may have deteriorated.
So your new 63 sounds like it’s a decent little improvement for now.

 

[Aggie Charlie]

Even though Centech uses essentially the same gauge charge wire (10 gauge), they claim that theirs is good for up to 100 A.
So you can keep that in mind and perhaps upgrade a little more if you decide to.
But just as was said above anytime you go over 70, but absolutely if you go over 100 you need to upgrade the charge wire.

The 95 amp 3G is a worthy update for any bronco. But it is definitely not a “no modification” upgrade.
Your original alternator would’ve been anything from 38 to 55 A rating. And then over time it may have deteriorated.
So your new 63 sounds like it’s a decent little improvement for now.

Thanks for the information. I greatly appreciate it, I will continue to research alternators and the options that are available.

 

[tampabronco]

Thanks for the information. I greatly appreciate it, I will continue to research alternators and the options that are available.

I went with a 92 ford Aerostar 2G small case alternator 95 amps (NAPA 2133086) when I upgraded to the holley sniper. Used a Painless wiring kit and removed the external voltage regulator. Bolted up to my OE alternator bracket and works great

 

[Broncobowsher]

Really don't like those 2G alternators. Those spade connectors on the power are well known to burn up. Not talking just a crusty connection, full on flames and fire burn up.

 

[ba123]

I bought one (and obv haven't installed yet) from https://js-alternators.com/. Not terribly priced for a whole lot of Amps. Can pay a little more and have the case powder coated to whatever color you want and Lifetime Warranty.

Their alternators are prob over the top and way too much, but I think better too much than not enough.

They have been great to work with so far and very responsive.

I can post a pic when I'm back home if anyone wants to see it. It's purdy.

 

[DirtDonk]

Of course! We love pics-o-parts.

Paul

 

[ba123]

Of course! We love pics-o-parts.

Paul

Haha, yeah, here it is.

It is pretty and like I mentioned JS has been great. I let them know that my project has taken an unexpected turn and they are working with me to change alternator styles since I unexpectedly am going Explorer front dress now and can’t mount this Mustang alt.

Also, they accidentally put the wrong pulley on there but as soon as I let them know, they immediately sent me the right serp pulley.

 

[tampabronco]

Really don't like those 2G alternators. Those spade connectors on the power are well known to burn up. Not talking just a crusty connection, full on flames and fire burn up.

Really don't like those 2G alternators. Those spade connectors on the power are well known to burn up. Not talking just a crusty connection, full on flames and fire burn

Really don't like those 2G alternators. Those spade connectors on the power are well known to burn up. Not talking just a crusty connection, full on flames and fire burn up.

It's not using a spade connector. It's the same 3 pin connector as a 3G. The 1 pin spade connector on the harness isn't connected and zip tied up

 

[Broncobowsher]

It's not using a spade connector. It's the same 3 pin connector as a 3G. The 1 pin spade connector on the harness isn't connected and zip tied up

Sounds like you are not dealing with a 2G. The 2G does not use a bolt on charge wire. It uses a double oversized spade connector. This is what they look like when they fail.

Pre-failure

 

[ba123]

that looks....exciting!

Reminds me of the time the 351 in my '53 pickup was doing some funky things. I drove that thing everywhere, had it running great but went to San Diego (almost 500 mi for me each way) and my exhaust manifolds would GLOW red and my buddy decided to light his cigarette on it. Man that pissed me off, but I did laugh.

I messed with the timing, but it ran great and then it would get too hot and die. Had to wait for it to cool and try to figure out what was going on.

This was 30 years ago, so I do not entirely remember, might have been the oil pump failing and then holding the cam back but I do have the oil pump shaft somewhere. It was work of art. Two thirds of the way home from that trip it finally gave out in the middle of nowhere Highway 5. The oil pump shaft snapped but before it did, it looked like one of those wrought iron decorative railing posts that are spun to look nice.

Like this, only a lot worse:

I gotta find that thing. Sorry to hijack the thread!

 

[DirtDonk]

That thing should be mounted like a trophy and placed on your desk in a place of honor!

 

[tampabronco]

Sounds like you are not dealing with a 2G. The 2G does not use a bolt on charge wire. It uses a double oversized spade connector. This is what they look like when they fail.
View attachment 894746

Pre-failure
View attachment 894748

That's ugly. Mine's a different setup so it may be a small case 3G. I'm using the Painless wiring 3G harness with a plug for internal VR and a red power wire that runs directly to fuse to battery