130 amp?
Cargo Master
Joined: Mar 2008
Posts: 2,577
Likes: 211
From: Washington
https://www.ford-trucks.com/forums/1...ator-swap.html
Here's a link to info on a 1G to 3G.
I am a fan of 1G alternators, very reliable.
But can you still buy a new one? How many times has it been rebuilt. Was it just a paint job and new brushes. You can probably buy a new 3G alternator cheaper on Amazon , then a rebuilt 1G at Napa auto parts store.
Another issue that has been brought up is belt squeak. On a 3G you can get a soft start voltage regulator. This will eliminate belt slipage.
It's possible the donor vehicle/engine combination you use might come with a soft start voltage regulator. I believe they were color coded, regarding different types and voltage set points.
One a 3G alternator, you still have the option to sense the voltage set point, closer to the battery.
On a 1 wire alternator, it is it's own reference point. This is often referred to as "the tail wagging the dog".
Another reason why I am not a fan of 1 wire alternators.
Jim
Here's a link to info on a 1G to 3G.
I am a fan of 1G alternators, very reliable.
But can you still buy a new one? How many times has it been rebuilt. Was it just a paint job and new brushes. You can probably buy a new 3G alternator cheaper on Amazon , then a rebuilt 1G at Napa auto parts store.
Another issue that has been brought up is belt squeak. On a 3G you can get a soft start voltage regulator. This will eliminate belt slipage.
It's possible the donor vehicle/engine combination you use might come with a soft start voltage regulator. I believe they were color coded, regarding different types and voltage set points.
One a 3G alternator, you still have the option to sense the voltage set point, closer to the battery.
On a 1 wire alternator, it is it's own reference point. This is often referred to as "the tail wagging the dog".
Another reason why I am not a fan of 1 wire alternators.
Jim
Last edited by JimsRebel; Jun 16, 2026 at 01:46 PM.
Lead Driver
Joined: Jul 2017
Posts: 9,618
Likes: 1,186
From: San Jose, CA
Me too neither...
One wire is just for super simple and showy cars that hate extra wires. A 3-wire has it all going on except for fewer wires.
I forgot about the belt squeal issue. Even the large case 1G's that I installed had the issue to a certain extent. My guess is that, aside from more potential load from the output (when the demand is there) the internals are probably bigger and heaver as well. Putting the strain on the belt friction of only one V-belt.
My usual two solutions are, either a dual-groove V-belt when that's an option, or a larger diameter, deeper groove alternator pulley. With the slightly larger diameters, it's not enough to lower the performance of the alternator enough to cause a problem. Unless you go too big, of course. But that's not usually an issue, as pulley availability is better now than in the old days.
Paul
One wire is just for super simple and showy cars that hate extra wires. A 3-wire has it all going on except for fewer wires.
I forgot about the belt squeal issue. Even the large case 1G's that I installed had the issue to a certain extent. My guess is that, aside from more potential load from the output (when the demand is there) the internals are probably bigger and heaver as well. Putting the strain on the belt friction of only one V-belt.
My usual two solutions are, either a dual-groove V-belt when that's an option, or a larger diameter, deeper groove alternator pulley. With the slightly larger diameters, it's not enough to lower the performance of the alternator enough to cause a problem. Unless you go too big, of course. But that's not usually an issue, as pulley availability is better now than in the old days.
Paul
Lead Driver
Joined: Nov 2000
Posts: 6,647
Likes: 352
From: Albuquerque
In my case of slippage it seems to be constant, more after warmup. I could put a double pulley (or serpentine) but there's no option for the crank pulley. I have a three groove one to the alternator, one to the AC, and one to the power steering. A wider belt probably wouldn't do any good either as the existing fills the groove. I ordered a belt ajustment tool that mechanically pushes things apart, it's hard to find a point to pry on. So I'll get it tighter that Dick's hat band and hope it dosen't kill the bearing (should be heavy duty on a heavy duty alternator?)
Lead Driver
Joined: Mar 2008
Posts: 7,195
Likes: 387
From: Near Los Angeles
I agree with the others: If there is no need, stay with the oe alt.
I changed to a 130 amp for several reasons. My wiring in that area was very poor, so I wanted to upgrade. Then I wanted to power a amplifier, add to that halogen lights, and dual electric fans. I used the alt out of a 94 taurus. It was a bolt in. I did, however, have to swap to a dual V belt pulley. It has been good for maybe 4 years. I also pulled a replacement from the j/y because I found a great vid on youtube about how to rebuild these alts. The youtuber was also selling parts.
Good luck. Btw, that is a very nice truck you have.
I changed to a 130 amp for several reasons. My wiring in that area was very poor, so I wanted to upgrade. Then I wanted to power a amplifier, add to that halogen lights, and dual electric fans. I used the alt out of a 94 taurus. It was a bolt in. I did, however, have to swap to a dual V belt pulley. It has been good for maybe 4 years. I also pulled a replacement from the j/y because I found a great vid on youtube about how to rebuild these alts. The youtuber was also selling parts.
Good luck. Btw, that is a very nice truck you have.
Lead Driver
Joined: Jul 2017
Posts: 9,618
Likes: 1,186
From: San Jose, CA
In my case of slippage it seems to be constant, more after warmup. I could put a double pulley (or serpentine) but there's no option for the crank pulley. I have a three groove one to the alternator, one to the AC, and one to the power steering. A wider belt probably wouldn't do any good either as the existing fills the groove. I ordered a belt ajustment tool that mechanically pushes things apart, it's hard to find a point to pry on. So I'll get it tighter that Dick's hat band and hope it dosen't kill the bearing (should be heavy duty on a heavy duty alternator?)
I did pick up a great tool though, which is just a glorified half-moon thingy with a little bit of tang/grip at one end, and a 1/2" drive ratchet hole at the other. Get it caught on something and you can put some good torque on things with just one person.
I had squealing pretty often too. The lucky ones only have it on start-up. Especially on cold, moist mornings where belt slippage is a constant thing.
With my old Bronco, finding pulleys that fit was still a pain, but I did not have any real issues once I found a set with matched offset. After all, mine only came with a single groove/sheave pulley on the crank and water pump from the factory. No power steering, air pump, or A/C to confuse things.
Often worried about that on my 400, because the crank pulley was already a four or five groove jobby, with none of them the same diameter!
So a larger alternator pulley was really called for. Luckily too, even though it was the higher output alternator (105a) it had a much more seldom squeal to deal with.
Paul
Last edited by 1TonBasecamp; Jun 16, 2026 at 03:34 PM.
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Hotshot
Joined: Feb 2004
Posts: 10,861
Likes: 2,624
From: The Shenandoah Valley
Interesting read here, and somewhere I saw mention of portable power. I have a couple add on inverters that were given me as Christmas gifts two years in a row from the same BIL, just a few hundred watts, enough to maybe run a drill or charger for cordless tool batts. Was a time I could have even used one. If out yonder away from spare batteries or house current, maybe doing a lengthy job, or camping, an inverter makes sense, but I'd likely run it off a dedicated car battery, not my truck's start battery.
130 amps at 13.2 volts is over 1700 watts, reduce for heat waste and engine at idle, still some good current remains. In July 2012 after a derecho, we were without power for a week, my generator got some use here at home .... a friend at work had none and every day he came to work with batteries to recharge, he was using them with an inverter to keep a small refrigerator going and a fan for him, etc. They were his race car batteries.
130 amps at 13.2 volts is over 1700 watts, reduce for heat waste and engine at idle, still some good current remains. In July 2012 after a derecho, we were without power for a week, my generator got some use here at home .... a friend at work had none and every day he came to work with batteries to recharge, he was using them with an inverter to keep a small refrigerator going and a fan for him, etc. They were his race car batteries.
Last edited by tbear853; Jun 17, 2026 at 11:04 AM.
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