Old Ford 300 I6 alternator -- ID and how to excite?

[D60]

This alternator is on a carbureted Ford 300 being used for an irrigation pump. I've been saying it's a 1976 for basic parts look-up, but I have no idea.

The alternator is not charging. The BATT wire is receiving battery voltage but this is not exciting it -- or the alternator is bad.

The existing alternator doesn't look exactly like catalog pics (for '76 or '83). I don't know if this is due to running design changes, or someone installed something else. The entire setup is cobbled together as old irrigation pumps tend to be.

RA suggests this:

This is what is there. Does it look familiar to anyone and is that an internal regulator I see in there? There's no regulator on the engine and I have no idea if it ever charged.

 

[mk378]

What is on there now is actually a GM alternator, probably a "one wire" version which is something that third parties came up with for the hot-rod market.

The non one wire version needs a plug with two small wires on the hole marked 1 2 on the side. The one wire regulator may still have pins for that plug but they are not used.

 

[Trav]

Momentarily jump the field connection with 12v from the BAT terminal (it may spark, that is normal) then see it starts charging.

 

[D60]

Momentarily jump the field connection with 12v from the BAT terminal (it may spark, that is normal) then see it starts charging.

That's the question -- is that a Field terminal? I honestly don't know, I'm weak in this field (pun? Oof.....)

 

[Trav]

It should be marked FLD or R, on the old alt that one with your white arrow appears to be the field.

 

[D60]

It should be marked FLD or R, on the old alt that one with your white arrow appears to be the field.

Thanks Trav, I zoomed in on my photos and can't make out a marking there but I'll look more closely in person. Worst case, I'll just try it briefly.

 

[eljefino]

Measure between the two ears, it'll either be 7 inches or 8.25. These will be small- and big-block alts.

Your truck from the factory should have a "1G" alt. Good news is you can replace this with a 2G (bleh) or 3G (good.) 3Gs were big in the 1990s and all over the place in both RWD Mustangs and FWD Taurusses etc.

You can get a 110-ish amp from a junkyard from a disposable car like the Taurus which will be cheaper and outperform your 1G or whatever you have now. You'll need the pigtail, and the pulley will swap right over-- use an impact to get the nut off, it'll come right off. Lots of how-tos on the internet.

Edit: The pulley, if it's GM, may not have the same internal diameter. If you look at the upper mount there's some shenanigans going on. Ford alts will have a "wide side" and a "bolt to the adjustable slot side". But the one pictured has a spacer taking up space.

 

[Chris142]

Run a jumper from the big charging wire to the #2 terminal, you may need to energize the #1 terminal depending oñ the engine rpm

 

[D60]

Measure between the two ears, it'll either be 7 inches or 8.25. These will be small- and big-block alts.

Your truck from the factory should have a "1G" alt. Good news is you can replace this with a 2G (bleh) or 3G (good.) 3Gs were big in the 1990s and all over the place in both RWD Mustangs and FWD Taurusses etc.

You can get a 110-ish amp from a junkyard from a disposable car like the Taurus which will be cheaper and outperform your 1G or whatever you have now. You'll need the pigtail, and the pulley will swap right over-- use an impact to get the nut off, it'll come right off. Lots of how-tos on the internet.

Edit: The pulley, if it's GM, may not have the same internal diameter.

Actually I thought the 3Gs were Mustangs but the mid '90s Taurii got something else? Typically 90A and external fan, but larger than the 2Gs in the OBS EEC-IV trucks.

That's what I had swapped into my '90 Bronco because allegedly they ran cooler during things like winching than the 3G with it's tiny case and internal fan.

We used to have to clock the Taurii case halves 180 because otherwise the plugs were pointing down, inaccessible.

 

[Chris142]

I tried lol

 

[D60]

Actually I thought the 3Gs were Mustangs but the mid '90s Taurii got something else? Typically 90A and external fan, but larger than the 2Gs in the OBS EEC-IV trucks.

That's what I had swapped into my '90 Bronco because allegedly they ran cooler during things like winching than the 3G with it's tiny case and internal fan.

We used to have to clock the Taurii case halves 180 because otherwise the plugs were pointing down, inaccessible.

The Taurii alts I'm thinking of may have been the 6S? I think?

Upon searching I now remember even in stock form the claim to fame was great output at idle (see again: winching). The 3G was maybe up to 130A? but you had to be wingin' it to get decent output and as mentioned they allegedly didn't cool as well with an internal fan

 

[meep]

Looks to me like an internally regulated, 1 wire GM (delco-remy). Also, the little post with the white arrow … doesn’t look like it can take power because any nut screwed down to it will press into the frame … ground. Looks like a 1-wire unit to me. If so, you can’t excite it externally.

A replacement won’t be big bux. A one wire or internally-regulated with a power-on lead would both work.

 

[eljefino]

Your mystery stud/ white arrow is probably something (diode pack) screwed into the case from inside.

 

[jhellwig]

Looks like a Delco 10SI or 12SI. There is a wiring connector missing where Chris drew the red line to. The alternator is actually upside down. There are two terminals that point out to the side of the alternator.

The connector looks like this https://www.rockauto.com/en/moreinfo.php?pk=942468&cc=1299315&pt=2528&jsn=739&_nck=Ekt6BqBF1pwlXdx0gYlm1esw98pF26vehMm/GG3C/l2QOXSJubi7WSmJDED/poBfgGB2ZttQ+73lW7wn5W7ZTZcFbFYmsuqo3DrytQ9pm3WmtTrUVkh1iGJuLiuY1qh1uxnxEZ8S+WrDMxd8PL9Ara2NAPKbTdRBRx5LuBDAiGF5Wn5JvuQfiXazItbyJeMa4CSy/k+MjHdFavO+v7xZQj18+oZHPeZO37mZfY1PRbr3Nk9Ml1ddhoCX6b/DnDE/NiKFf5W4DmNCCDJZKRA+ViSZMQuhYb7VxRUMuvTYyPamQEoQ+qohUX112HvBLaxPqnLeYIKYRn7MGNFVf0hR+NRHE3oorDUe unless is had a one wire conversion done to it. The red wire goes to the battery terminal and the white goes to the ignition.

Here is a good explanation of the Delco alternators. http://www.madelectrical.com/electricaltech/delcoremy.shtml

 

[meep]

Looks like a Delco 10SI or 12SI. There is a wiring connector missing where Chris drew the red line to. The alternator is actually upside down. There are two terminals that point out to the side of the alternator.

The connector looks like this https://www.rockauto.com/en/moreinfo.php?pk=942468&cc=1299315&pt=2528&jsn=739&_nck=Ekt6BqBF1pwlXdx0gYlm1esw98pF26vehMm/GG3C/l2QOXSJubi7WSmJDED/poBfgGB2ZttQ+73lW7wn5W7ZTZcFbFYmsuqo3DrytQ9pm3WmtTrUVkh1iGJuLiuY1qh1uxnxEZ8S+WrDMxd8PL9Ara2NAPKbTdRBRx5LuBDAiGF5Wn5JvuQfiXazItbyJeMa4CSy/k+MjHdFavO+v7xZQj18+oZHPeZO37mZfY1PRbr3Nk9Ml1ddhoCX6b/DnDE/NiKFf5W4DmNCCDJZKRA+ViSZMQuhYb7VxRUMuvTYyPamQEoQ+qohUX112HvBLaxPqnLeYIKYRn7MGNFVf0hR+NRHE3oorDUe unless is had a one wire conversion done to it. The red wire goes to the battery terminal and the white goes to the ignition.

Here is a good explanation of the Delco alternators. http://www.madelectrical.com/electricaltech/delcoremy.shtml

You saw what I couldn’t. I wanted to find that traditional connector. Red wire is sense, white wire is power. Seems like that connector should then be hanging around the engine harness somewhere in his case?

 

[jhellwig]

You saw what I couldn’t. I wanted to find that traditional connector. Red wire is sense, white wire is power. Seems like that connector should then be hanging around the engine harness somewhere in his case?

After some looking on the one wire conversion there is no way to tell the difference between one and three wire alternators. If it has a one wire conversion it is dead.

 

[clinebarger]

A lot of older stationary equipment ran self exciting Delco SI alternators, Might need to goose the throttle to excite it (RPM).

 

[D60]

Looks like a Delco 10SI or 12SI. There is a wiring connector missing where Chris drew the red line to. The alternator is actually upside down. There are two terminals that point out to the side of the alternator.

The connector looks like this https://www.rockauto.com/en/moreinfo.php?pk=942468&cc=1299315&pt=2528&jsn=739&_nck=Ekt6BqBF1pwlXdx0gYlm1esw98pF26vehMm/GG3C/l2QOXSJubi7WSmJDED/poBfgGB2ZttQ+73lW7wn5W7ZTZcFbFYmsuqo3DrytQ9pm3WmtTrUVkh1iGJuLiuY1qh1uxnxEZ8S+WrDMxd8PL9Ara2NAPKbTdRBRx5LuBDAiGF5Wn5JvuQfiXazItbyJeMa4CSy/k+MjHdFavO+v7xZQj18+oZHPeZO37mZfY1PRbr3Nk9Ml1ddhoCX6b/DnDE/NiKFf5W4DmNCCDJZKRA+ViSZMQuhYb7VxRUMuvTYyPamQEoQ+qohUX112HvBLaxPqnLeYIKYRn7MGNFVf0hR+NRHE3oorDUe unless is had a one wire conversion done to it. The red wire goes to the battery terminal and the white goes to the ignition.

Here is a good explanation of the Delco alternators. http://www.madelectrical.com/electricaltech/delcoremy.shtml

So red can be always hot and the white would also be always hot when running, like tied into the power to the ignition coil?

edit: I just don't wanna burn it up by full-fielding it 100% of the time

 

[mk378]

Yes with the standard internal voltage regulator:

Red wire is Sense. It draws a very small current to detect the system voltage. When the voltage reaches 14 or so, the regulator stops charging. The current is so small that the Sense wire can be connected to the battery all the time, or it can be after the ignition switch.

White wire is Lamp. This is fed from the ignition switch through the red Alternator warning bulb on the dash. It provides initial power to magnetize the rotor and start the charging process. After it is started, the alternator provides its own power and no current flows through the bulb. If there is a problem with the system the bulb stays lit.

The bulb is entirely optional and the white wire could also be connected straight to a "hot with key on" circuit. But it will run the battery down if left live all the time.

 

[D60]

Yes with the standard internal voltage regulator:

Red wire is Sense. It draws a very small current to detect the system voltage. When the voltage reaches 14 or so, the regulator stops charging. The current is so small that the Sense wire can be connected to the battery all the time, or it can be after the ignition switch.

White wire is Lamp. This is fed from the ignition switch through the red Alternator warning bulb on the dash. It provides initial power to magnetize the rotor and start the charging process. After it is started, the alternator provides its own power and no current flows through the bulb. If there is a problem with the system the bulb stays lit.

The bulb is entirely optional and the white wire could also be connected straight to a "hot with key on" circuit. But it will run the battery down if left live all the time.

Extremely helpful, thank you.

So just to be super extra mega clear: it won't burn anything up if both wires are fed 12V constantly? (not worried about battery drain when shut down)

I only ask because I remember WAY back in college my VW mechanic showed me how to full-field an Audi/VW alt to excite it but said it would burn up (the regulator?) if left that way, which is why exciter current is momentary. It's one of those random things from youth that sticks in your brain, from a time when you were capable of remembering things.

Not arguing, just trying to understand. With me, it's usually "Explain this like I'm a five-year-old"