Setting Regulator voltage on a Farmall 706

Replaced the regulator on my 1964 Farmall 706 Gas tractor. Its putting out 12.5V at idle and 15.8 volts at around 2100 RPM. Do i need to adjust this and if so how do I do it? Thanks

15.8 is a little high if your voltmeter is right. Depends on how you are using the tractor. Short stop & start, it may be OK. Watch the battery. If it is pushing acid out, the regulator needs to be set down a little.

(quoted from post at 10:25:18 04/21/11) Replaced the regulator on my 1964 Farmall 706 Gas tractor. Its putting out 12.5V at idle and 15.8 volts at around 2100 RPM. Do i need to adjust this and if so how do I do it? Thanks

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It takes a little while for the regulator to operating temperature, longer for the external regulator than the internal ones. Regulators are designed to allow a higher voltage when cold than they do when warmed up. Run the tractor for at least a half hour before deciding that any adjustment is necessary.

If it is a new regulator and is out of adjustment I would have it replaces rather than trying to readjust it.

Like Teddy says,

Watch that battery a few days to make sure it isn't "boiling".

A generator does that, as it's somewhat speed dependant.

After that battery levels out, betcha your readings are gonna settle right down.

Allan

Its the voltage at/on the battery that really matters NOT the open unloaded output of the genny only. That being said, I DONT THINK I WOULD DO ANYTHING FOR A WHILE. Right after a start up its normal for her to charge at a fairly high output, but after a while she ought to back off, see if that happens after 30 or so minutes at fast RPM. Yes 15 sounds a bit high IF THE METER IS ACCURATE??? and if it stayed there a long time you may overcharge and boil over. Id expect after a while it (battery voltage) should back off to like 13 to 14 volts depending on battery and genny and RPM.

Keep an eye out for excessive outgassing and/or acid boil over and have the battery tested and if its okay run her a while BEFORE messing with the VR, it may be doing its job or you meter may be off??

John T

First off, are you checking the voltage AT THE BATTERY?

No, on the regulator's center terminal.

(quoted from post at 08:40:55 04/21/11) No, on the regulator's center terminal.

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Always check the voltage AT the battery.

Ok, the local auto electric place told me to measure on the center pin and adjust the volts by bending the spring. thought i would ask you guys before i tried this. Thanks

As I already posted below..."Its the voltage at/on the battery that really matters NOT the open unloaded output of the genny"

The BAT terminal on the VR is basically battery voltage (if alls wired right)

The ARM/GEN terminal on the VR is basically the output of the Genny (IF ALL WIRED CORRECT).

However, if the VR is working once the gennys voltage exceeds battery voltage (like the 15 you mentioned) the cutout relay should close which essentially connects BAT and GEN/ARM together,.

Is this a 3 terminal (BAT ARM FLD) VR or a 4 terminal (BAT ARM FLD LOAD) VR ????

If its a 4, often GEN/ARM is off on one side or the bottom all by itself, while BAT LOAD and FLD are together... SURE ITS WIRED CORRECT????? IS IT A 3 OR 4 TERMINAL VR???

You need to see if its a 3 or 4 terminal VR and then see if its wired correct and then MEASURE BATTERY VOLTAGE and see whats happening. You may just be measuring the open unloaded output of the genny when it needs to be wired correct and then measure the battery voltage!!!!!!!!!!

Did you Polarize the Genny before start up???

Heres correct wiring:

BAT on VR to ammeter
FLD on VR to FLD on Genny
ARM/GEN on VR to ARM on Genny
(L)OAD on VR to light switch (if it has L )

I may be gone later but will check in when I return or the other good gents can get you going

John T

This should be a three unit regulator, (cutout, current regulator, and voltage regulator) so if you do any adjustments make sure you are on the correct unit. It will be the unit on one end that the points are closed when engine is not running.

Check the voltage at the battery, Voltage at the generator really means very little, as it does not take into account any voltage drop in the wiring.
At the battery posts, 14.2 is ideal, while up to 15V is a little hot, but will be OK.

If you do need to adjust the regulator, first make sure the ground wire from generator to regulator is clean and tight, as a poor ground will send a false low voltage signal to the regulator and cause high charging voltage.

The cover must be on the regulator when checking voltage after adjustment, as the magnetic field carried by the cover changes the regulsator setting a bit.

Another thought, what is the outside temp when you are reading this high voltage ? A battery needs higher voltage to charge at low temps, so the regulators are designed to compensate for low temp and increase charging voltage somewhat when it is cold.
Once again, check the voltage at the battery posts, you may have no problem at all, as checking at the generator may well give a false high voltage reading. The voltage at the battery is what counts.

its a 3 terminal VR. i'll check the voltage at the battery. thanks

Are you reading volts with a digital meter or an analog? If you have a digital meter, you could be getting all kinds of hash up by the regulator. I'd try setting/ checking things out back at the battery. Your voltages might not be as far off as you might think.

Or stick a delco SI10 alternator on there and be done with it. If it saves one battery it pays for the conversion.