Looking for help with wiring a 1 field regulator to a 2 field alternator

[Dana67Dart]

And what's the difference between that and what I'm doing by connecting the second field terminal to the ground thus creating continuity between the ground and the field wire/terminals

The voltage regulator provides a variable voltage to the field terminal. Think about a model train transformer. Turn the knob and the train gets more voltage and can go faster (do more work) turn up the voltage in the VR the alternator can do more work. Maintaining you battery vs. charging your battery while powering the headlights for example.

Your alternator is an Isolated field type meaning that both ends of the field coil are not attached to ground. By grounding one end and applying voltage to the other the field coil creates a magnetic field, rotating a coil of wire inside a magnetic field induces a voltage in the rotating coil, that's what charges your battery etc. the stronger the magnetic field the more power the rotating coil can provide

 

[slantsixdan]

The answer to the question you've asked is as simple as others have made it: pick one of the two field terminals on the alternator, either of them, and connect it to ground; that's all you have to do to make your existing regulator control your existing alternator.

Don't stop there, though. I am sorry to make this more complex for you, but be aware that the alternator presently on your truck is almost certainly capable of much higher output than the original and its field current, which passes through the regulator, is definitely higher. This throws a much bigger electrical load on a substantial percentage of your truck's wiring, and the ammeter — which means a significantly increased likelihood and consequence of an electrical fire.

There's a variety of ways to eliminate the danger. Some of them are better than others; some of them are easier than others. Read this, and get help from an auto electrician near you if needed. Ounce of prevention/pound of cure.

More generally: you can get yourself up to speed on old-car work with some reading. As soon as you can, get the three books listed in this thread.

 

[treebark]

The answer to the question you've asked is as simple as others have made it: pick one of the two field terminals on the alternator, either of them, and connect it to ground; that's all you have to do to make your existing regulator control your existing alternator.

Don't stop there, though. I am sorry to make this more complex for you, but be aware that the alternator presently on your truck is almost certainly capable of much higher output than the original and its field current, which passes through the regulator, is definitely higher. This throws a much bigger electrical load on a substantial percentage of your truck's wiring, and the ammeter — which means a significantly increased likelihood and consequence of an electrical fire.

There's a variety of ways to eliminate the danger. Some of them are better than others; some of them are easier than others. Read this, and get help from an auto electrician near you if needed. Ounce of prevention/pound of cure.

More generally: you can get yourself up to speed on old-car work with some reading. As soon as you can, get the three books listed in this thread.

I appreciate the additional advice/guidance.

 

[Muad'Dib15]

Question. Ive had an square back in my 66 for a long time. I've no idea what Amp it is anymore, but it's been fine with only a green wire hooked up, nothing done to the other terminal, and the output going straight to the battery. I have a mechanical voltage reg. Would grounding the other terminal by removing the bushing underneath or making a jumper do anything to improve the idle charging issues I have?

Edit: nvm the tab I wasn't using was cut already.

 

[67Dart273]

I missed part of this, don't know why. One last comment. ALWAYS ALWAYS ALWAYS CHECK the field for shorts to ground and incorrectly connected brush holders. This is the fault of REBUILDERS. Several guys have burned up wiring because of

ALWAYS check that an isolated field alternator (incorrectly referred to as "dual field" or "two fields" CHECK with an ohmeter for continuity between the two brush terminals AND that there is OPEN/INFINITY from the brush terminals to the case.

If you need to ground one, make CERTAIN that the opposite one is not already inadvertantly grounded by the rebuilder.

the first FU by a rebuilder I saw in this manner was about 1980 or so.