ovrszd and aczlan (and all),
I imagine you're right that the belt being too tight didn't break the pulley. I just don't know of any other causes (yet).
You mentioned that I should consider buying a new alternator, and that I should consider converting to 12-volt. Originally, when I was figuring I'd keep this tractor, I had considered that conversion. And, in fact, I still would consider it even though my intent is to sell it -- as long as it didn't cost a ton, and as long as it is within my capabilities.
Here is a list of the issues/questions I came across. Feel free to stop reading whenever you like.
Q1: I assume that, as I'm converting from 6 to 12 volt, I would also convert from positive-ground to negative-ground -- agree? If so, that leads to additional questions below.
Q2: Would I go with one of those kits that are for converting from 6-volt to 12-volt? I imagine yes. However, as I look at the various kits, there are a number of questions, ambiguities, and inconsistencies. Examples listed below, with questions.
Q3: I found a kit that might apply, but, in the lengthy list of which tractor models & years it applies to, although it includes 1964 Ford 4000, it then says "does not apply to Industrial models", which is what I have. Do you know what difference there is between an Industrial and a non-Industrial, such that this electrical conversion kit would not apply? (FYI - that product page did not happen to include a link to a kit that would apply to Industrial.)
Q4: One kit includes the alternator, wire harness, and mounting brackets, but nothing else. That kit specifically states that it doesn't include the coil because "the ignition system remains at 6 volts". Meanwhile, another kit (different manufacturer, different seller) includes the coil. How would I decide if I should change the coil or not?
Q5: At least one kit refers to the question of whether my tractor's proofmeter is driven off my generator. My guess is that, since the current one is a one-wire alternator, it does not drive my proofmeter. Correct?
Q6: My search also introduced me to the term "self-exciting alternator", with one forum member stating something about requiring the engine to be running at higher RPMs in order for the alternator to actually charge the battery, and the response was that the 3-wire versions were better in that respect. Is that true? And should I care about that and change to a 3-wire alternator? Here's a basic question demonstrating my lack of experience in this area: Given that the current configuration expects a 1-wire alternator, if I were to convert to a 3-wire alternator, where do the other 2 wires go?
Q7: When talking with a friend about converting to 12-volt with negative ground, he also mentioned the starter. A number of people in forums have said that sending 12 volts to a 6-volt starter is okay -- it'll just spin faster. But even if true, he asks if the conversion from positive-ground to negative-ground would cause the starter to run backward, such that I would need to replace that too. And yet, none of the "kits" or the forum discussions that I've found mention that concept. What do you think?
Q8: Along those same lines, I'm guessing that alternators themselves are also specific to positive-ground vs. negative ground. Is that right?
Q9: Going back to question 7 regarding the starter: My friend said that perhaps it makes sense to convert from 6-volt to 12-volt, but leave it at positive-ground. His point was that I could avoid buying a starter. Of course, by making that decision, that would affect the other things too, e.g. the alternator would need to be positive-ground, and I'm not sure how easy it would be to find one like that.
Q10: One kit mentioned the need to change the gas gauge to 12-volt, but the kit did not include it. Would I therefore need to look for the sending unit, the instrument panel gauge, or both? Is the change just due to the conversion to 12-volt, or also due to the conversion to negative-ground?
Q11: How about the other 2 gauges -- temp and oil pressure: Are they driven electrically, such that I need to replace those either because of the 6v to 12v change or because of the positive-ground to negative-ground change?
Q12: Are there other electrical components to be considered? Light bulbs, of course. Others?
Those are all the questions I could think of, but I would not be surprised to learn that there are more.
Cost: I'm seeing 6-volt to 12-volt conversion kits for about $175. On top of that would be a 12-volt battery ($80?) and light bulbs (probably negligible), plus some of the "oh, by the way" items (e.g. starter, coil, gas gauge, etc., depending on the answers to those questions above). Depending on those answers, this project sounds like it could push its way into the $400 range. I'd even be okay with that if I thought the tractor would sell better and be worth most of that additional money. I'd consider it a learning experience. But as you can see by my questions, there are some fairly basic things I just don't understand yet -- like "Will the current starter run backward?", and "Which gauges would be impacted by the conversion?"
In case you're interested, here's a bit more info on the tractor:
Model: 41301 S
Serial: 57788
The engine is gas, 4-cylinder.
It has about 4100 hours.
The transmission is 4-speed with fwd/rev shuttle.
Thanks again for all your input.