Install alternator - 3 posts but 2 wires
- Thread starter Brian Bearor
- Start date
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One of the flat blades needs to go to ground.
68HemiRR
Well-Known Member
That appears to be a 1972 and later square back. You need a 1969 and earlier round back.
MoparLeo
NRA BENEFACTOR LEVEL LIFE MEMBER
Old valiant ? What year, the wiring changed
Click here for more information on using 1 field and 2 field alternators.-> Google Search
Click here for more information on using 1 field and 2 field alternators.-> Google Search
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Brian Bearor
Well-Known Member
1963
Check to see if one of the terminal blades is actually grounded to the case, remans started doing that as a 'fitsall' way of covering more models with the available cores. If so, put a vacuum cap on it & attach the wire from the regulator to the one that shows resistance to the case. If there's no continuity to the case, then the insulating washer needs to be removed on the fld. one & replaced with a metal one...then capped.
*EDIT* This assumes You are running a stock mechanical regulator contolling the B+ to the alt. rotor field!
He can make that work just fine
THIS!!! Pay attention!!! Read it again!!! Many rebuilts/ etc that have two field terminals --and they are supposed to BOTH be isolated from ground----many come with one mistakenly GROUNDED. Worse, sometimes the grounded one has a flag/ spade connector tab and so it is not obvious.
Alternatively, if both field terminals are properly isolated, you can add one more wire and use the matching 70/ later electronic regulator, which is a better setup. You'll need a pigtail connector for the new VR if that is what you do. You re-use the old wires and add one more
The one at 12:00 in your photo is cut off by the rebuilder. That means it is internally grounded. You can rest this out by measuring with an ohm meter.
That terminal to the alt to the case should read the same as if you touch the two leads to her.
The other terminal to the case should read a few ohms 5????
It is a rebuilt Square back wired for a grounded field regulator
Many rebuilds use a Isolated field alternator (square back) because round back core are few and far between.
They cut off the tab of one of the terminals and don't put in the insulating parts so that terminal is grounded (ON PURPOSE)
This making an isolated field alt electronically a grounded field alt.
Red - is clipped off, no wire goes to it, it should be grounded to the housing
Blue - no insulating washer under screw
Green - is not clipped off, feed from the voltage regulator goes here
Yellow - black insulating washer
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If that's the case, all he has to do is connect the large red charge wire and the one field wire and he's in business. When I did Vixen's square back conversion, it did not come with one field terminal grounded. I just removed the blade, removed the insulator and screwed it back together.
Looking closely, that appears to be a metal washer under the tab at 12:00, it's a bit fuzzy esp. blown up..........I don't like the way they nip those terminal blades, because there's enough left for someone to mistakenly get a female spade over it anyways,....yes, should be -0- Ohms at top blade, 3-4 Ohms at the full blade.
Mattax
Just the facts, ma'am
Spend a few minutes verifying as Killer6 recommends.
Its not worth the risk of assuming. Connecting the green wire to a grounded terminal will blow the fusible link in the voltage regulator, or burn something up.
I suspect sqaurebacks are more common because (a) they made more of them (b) they require a diode press and soldering skills rather than bolt in rectifiers which can be had for cheap.
Save the original alternator if you have it. Either you or someone else may want it for repair or rebuilding. A common issue with new rebuilds is the rotors often draw far more current than the originals.
Its not worth the risk of assuming. Connecting the green wire to a grounded terminal will blow the fusible link in the voltage regulator, or burn something up.
I suspect sqaurebacks are more common because (a) they made more of them (b) they require a diode press and soldering skills rather than bolt in rectifiers which can be had for cheap.
Save the original alternator if you have it. Either you or someone else may want it for repair or rebuilding. A common issue with new rebuilds is the rotors often draw far more current than the originals.
No, Dana, it only means it is grounded IF THE REBUILDER ASSEMBLED IT CORRECTLY. I highly recommend you check with a meter!!
I agree to check but it's more likely they are assembled correctly then not.
Personally I would like to see the grounded terminal be cut flush with nothing protruding
slantsixdan
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…and it is very(!) likely capable of much higher current output (amps) than the original. Read this soon and carefully if you want to avoid a car-b-que.
Brian Bearor
Well-Known Member
Thank you
Mattax
Just the facts, ma'am
Learn what you have and how it works before hacking up your car.
Yes if you ignore the ammeter when its maxing out, something will fail.
Immediate issue is determining whether what you bought is set up as we think.
Second, if the car was running without the alternator for a while, then the battery is run down a bit. Put the battery on a slow charger before restarting the car. Using an alternator to recharge a very low battery is one way the circuit gets damaged. Extended high charging current can also damage the battery and the alternator. See Warning
Then you can measure the field's current draw if you want to know whether it will be a problem with your '63.
As far as vulnerbilities go, the good news is the '63 had a ring terminal connection at the firewall. However while its better contact than the push in terminals, it doesn't mean it can handle excessively high current or is corrossion proof. We've seen at least two example posted here where they got overheated. follow this post for examples
Also, '63 did not have a fusible link. So if you see the ammeter peg, and it doesn't return to center with key off, immediately and quickly disconnect the battery (negative first). Odds of that happening are low, but consequences are high.
Yes if you ignore the ammeter when its maxing out, something will fail.
Immediate issue is determining whether what you bought is set up as we think.
Second, if the car was running without the alternator for a while, then the battery is run down a bit. Put the battery on a slow charger before restarting the car. Using an alternator to recharge a very low battery is one way the circuit gets damaged. Extended high charging current can also damage the battery and the alternator. See Warning
Then you can measure the field's current draw if you want to know whether it will be a problem with your '63.
As far as vulnerbilities go, the good news is the '63 had a ring terminal connection at the firewall. However while its better contact than the push in terminals, it doesn't mean it can handle excessively high current or is corrossion proof. We've seen at least two example posted here where they got overheated. follow this post for examples
Also, '63 did not have a fusible link. So if you see the ammeter peg, and it doesn't return to center with key off, immediately and quickly disconnect the battery (negative first). Odds of that happening are low, but consequences are high.
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slantsixdan
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