One alternator I have (3G) has terminal marking as A for Armature, S for Stator, and I for Ignition. An alternator from a 90 351 has 2 of the same markings. Instead of an A it has a letter F for Field. Are these the same?
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Alternator markings
- Thread starter Bart
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Broncobowsher
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There is no field with the 3G. Go back to the regulator and take the "A" wire and run that to the alternator.
The "A" is often just tied back into the output post. But it should really be run back to the battery. It is the wire that is used to measure the battery voltage and adjust the regulator to get the desired output. The I turns it on, it needs to be switched or else the alternator will run the battery down trying to get output from a non-spinning alternator.
The "A" is often just tied back into the output post. But it should really be run back to the battery. It is the wire that is used to measure the battery voltage and adjust the regulator to get the desired output. The I turns it on, it needs to be switched or else the alternator will run the battery down trying to get output from a non-spinning alternator.
that's right there is no A on a 3G, but there is on the unit I'm going to use instead of 3G. Like wise there is no F on a 3G but there is on the alternator ill be using.There also no external regulator used on either alternator
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Sounds like a 2G which is anything but desirable for our rigs.
I suppose with the upgraded aftermarket replacement main connectors it can be made reliable, but they were notorious fire-starters and wire-melters back in the day.
Got a pic? Does it have a connector with two large Black wires sticking out of it? Or is it missing it's connector?
Paul
I suppose with the upgraded aftermarket replacement main connectors it can be made reliable, but they were notorious fire-starters and wire-melters back in the day.
Got a pic? Does it have a connector with two large Black wires sticking out of it? Or is it missing it's connector?
Paul
Morning Paul. On the side of the "new" alternator is the numbers 100AFOUU AA E240 C
I took two photos. Don't worry about the "V" pulleys I just put them on to keep from loosing them. In the second photo I have the 3G next to the "replacement" and you can see it's much smaller. I guess I could make brackets and reinstall it in place of the original. There is only two small wires coming out of it. One is connected to the terminal marked "F" (field) and the second one is "S" for Stator. Large battery wire and grd are the only other markings on it.
I guess I can make brackets and adapt the 3G into the serpentine belt system. Not sure yet if it'll line up with everything else.
I took two photos. Don't worry about the "V" pulleys I just put them on to keep from loosing them. In the second photo I have the 3G next to the "replacement" and you can see it's much smaller. I guess I could make brackets and reinstall it in place of the original. There is only two small wires coming out of it. One is connected to the terminal marked "F" (field) and the second one is "S" for Stator. Large battery wire and grd are the only other markings on it.
I guess I can make brackets and adapt the 3G into the serpentine belt system. Not sure yet if it'll line up with everything else.
Attachments
I was just informed by the guy I got the engine from that another van (same as the donor) has an external regulator. Now I'm concerned if it's the questionable 2G. Got me worried Paul.
Broncobowsher
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It's not the 2G. The 2G is a built in regulator. The real hot point for the 2G is the output terminals are big spade connectors. The spade connectors are well known for getting a poor connection and that creates heat and the terminals will literaly burn up. It is the only alternator I have ever found that tried spade connections for the output. Everything before and since (and every other manufacturer) uses a bolt on connection for the power wire.
I have no idea what that mystery alternator is. Which leaves me thinking that it being a unicorn of unknown I would be reluctant to even try using it because sourcing another at a later date is likely to be very difficult. Stick with known stuff you can take care of later when need be.
I have no idea what that mystery alternator is. Which leaves me thinking that it being a unicorn of unknown I would be reluctant to even try using it because sourcing another at a later date is likely to be very difficult. Stick with known stuff you can take care of later when need be.
I gave up on the unicorn alternator. Even though the 3g is 1 inch narrower than the unic I can make a plate to make it fit in the serpentine bracket.
Next question is "is there an internal cooling fan inside the 3g case? It sure looks like there is one.
Next question is "is there an internal cooling fan inside the 3g case? It sure looks like there is one.
3g installed with a 1 inch extension bracket. Hopefully I can upload a photo.
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The alternator in the pics is a good old tried-and-true large case 1G externally regulated alternator. Same basic function as original, using the same regulator as original.
They were usually found on larger trucks and ambulances and police vehicles.
They were the heavy-duty version and came in ratings starting at about 65 amps and running to 100/105 amps in their stock forms, with some in the 150 range I think for the ambulance applications. Aftermarket companies made them in up to 250 amp versions.
It was a good first step upgrade from stock on a Bronco, as they fit the stock brackets and had killer output down at low rpm levels. I still run a 70 amp version on my '71 and a 100 amp version on my F350.
Good alternator, unless you want to get rid of the external regulator and tidy up under the hood.
Paul
They were usually found on larger trucks and ambulances and police vehicles.
They were the heavy-duty version and came in ratings starting at about 65 amps and running to 100/105 amps in their stock forms, with some in the 150 range I think for the ambulance applications. Aftermarket companies made them in up to 250 amp versions.
It was a good first step upgrade from stock on a Bronco, as they fit the stock brackets and had killer output down at low rpm levels. I still run a 70 amp version on my '71 and a 100 amp version on my F350.
Good alternator, unless you want to get rid of the external regulator and tidy up under the hood.
Paul
Thanks for the info Paul. I spent about half of yesterday fabing a 1" extension so as to put the 3G in place of the larger 1G. I guess I'll leave it there for now. Time to get the Bronco engine broke in and miles on the new engine before the next scheduled outing.
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What did you have to extend? Only thing I did to mine was to elongate the slotted hole in the lower bracket to let me use the same belt as before. Otherwise it's a straight bolt-on for the big 1G and the 3G alike.
Maybe you were running into a belt issue as well? Or was something else in the way?
Those with the big cast steel alternator/air pump brackets definitely have to do some work, but most of us with the standard stamped steel triangle plate and curved arm mounting don't have many issues.
Sounds like you're there though, so however it gets done it's still done and running. Be good to get some miles under it's belt.
Paul
Maybe you were running into a belt issue as well? Or was something else in the way?
Those with the big cast steel alternator/air pump brackets definitely have to do some work, but most of us with the standard stamped steel triangle plate and curved arm mounting don't have many issues.
Sounds like you're there though, so however it gets done it's still done and running. Be good to get some miles under it's belt.
Paul
thanks, that's why it took me several hours to fab it. I'm still on the fence as to which alternator ends up in there after I break in the engine. I have two more EBs I'm glad that the 1G will work with stock Broncos . This one ended up with serpentine belt. I "think" "hope" that I have everything ready for the 20 minutes/2,000 rpm break in. Given it an hour to sit back and review everything.
Plus this mess is a serpentine belt song and dance. Good news is that I just finished breaking in newly rebuilt engine. Fired at the touch of the key. Sweet!!! 20 minutes at 2,000 rpms. Oil changed, now a few minor things and get 500 miles on it before off roading. 
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Yes and no. Works great and is a good reliable alternator and easy to connect to stock wiring with just a little modification. My 70 amp version lasted 15 years in daily driving, a few more after that, and then ended up on Mtfit's red buggy doing extra hard labor there as well unless he changed it out after getting it.
But looking at the numbers you posted I'd have to say yours is the 100 amp version. While it would probably work for awhile on the stock wiring, there is no guarantee it won't melt down your Black wire when you least expect it.
Anything over 70 amps is usually recommended to work with a larger gauge and much shorter charge cable than the Black w/yellow 10ga stock one.
With 100 amps and potentially even more depending on the build, you're better off with running a short length of 6ga cable from the alternator's BAT terminal directly to the starter relay and battery.
If you have 8ga wire laying around that would work fine as well. But if you don't it's easier to find 6ga to use.
We sell this kit: https://www.wildhorses4x4.com/product/Battery_Charge_Cable_AMG_fused/Bronco_Starters as a mega-upgrade to modern specs. Good for basically anything short of 200 amps (we fuse them for 175a) and easy to connect.
You can make your own, or buy one already made up like that.
Just don't run it through the stock 10ga wire. It's just too long for that gauge of wire running more than 70 amps.
Paul
Very interesting information. Wouldn't this also apply to the 3G? As a rule, while they are capable of pumping out this many amps, they wouldn't unless they are trying to keep up with some serious load (i.e. hard working winch with already low battery(s)). I have several of those 175 amp inline blade fuse on cables running from alternator to first battery and from first to second battery and from second battery to winch. I also have upgraded cables running though out the charging system. Being a retired High voltage electrician, I'm a firm believer in over kill. I think the only place I don't have the over kill is the short piece of 10 awg between alternator and first fuse on the passenger side fender. HMMM better look into that. Thanks no matter how educated we think we are we can always learn something new.
I usually make my own cables but I'll look at the WH line. Thanks again. It's 5 a.m. and I'm up ready to attack it again. Gotta get the Bronco off the lift. A friend has been waiting, patiently, for almost a month for me to reinstall his AOD in his '50 Ford convertable. He has too many sweet oldies (all Fords). I have not "infected" him with the Bronco bug "yet". ;D At 6'7" he'd need the FSB though. Thanks again for all your help. The Bronco world is a better place because of you being on this site.
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Yes, absolutely! Even a standard garden variety 3G usually is capable of putting out more than it's rating. The ones that have test-sheets with them often put out 10, 20 or even 30 amps more than their ratings.
But 3G upgrades are actually why we started offering the big cable and fuse kits in the first place. You NEVER connect a 3G to your original wiring!
You're right about them not working hard unless needed. Probably 90% of the time the stock wiring can handle the 20 or 30 amps that they put out during normal use. But it's that one time that you ask it to put out 130 amps, or something goes wrong with the regulator and it puts out 160 constantly that you're going to regret quickly not upgrading the wiring.
All it takes is once...
Paul
But 3G upgrades are actually why we started offering the big cable and fuse kits in the first place. You NEVER connect a 3G to your original wiring!
You're right about them not working hard unless needed. Probably 90% of the time the stock wiring can handle the 20 or 30 amps that they put out during normal use. But it's that one time that you ask it to put out 130 amps, or something goes wrong with the regulator and it puts out 160 constantly that you're going to regret quickly not upgrading the wiring.
All it takes is once...
Paul
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Perfect! We have a long-standing saying around here, that especially when it comes to battery cables, "overkill is just enough!"
We're happy to offer the kits, but if you usually make your own there's no reason you couldn't do so here too. If ours fits your needs, great. If you need more of less length at one end or another, roll 'yer own.
Happy to have your business either way.
Have fun!
Paul
Checking that jumper wire from the 3G to the first fuse I did upgrade it to what looks like 8 awg., but it is only 7 strand. I think I'll upgrade it to a fine copper wire 6 awg for more flexiblity (a lot like welding wire).
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