6 volt engine into 12 volt tractor, which voltage to use?

Hey guys. I've got a diesel 641 with a bad engine, 12 volt electrical system. It has an alternator, not sure if that's how it would've come from the factory, or if it would've had a gen.. It came to me with a brand new 12v battery.

I'm transplanting in a gas engine from a 640, which has a 6v electrical system. I believe that system is complete, except that it has no battery.

Should I use the 12 or the 6 volt system? Cost to get working vs effectiveness are the significant factors, this tractor is no show piece.

Thanks for your opinions, Alex
 
Good to know about the original generator setup JMOR. So being that I found my 641 with an alternator hooked up instead of a gen, does that mean that anything else has been switched over? Regulator etc?

And Virgil, that's what I was figuring, but I am a no brainer when it comes to electrical stuff, so I didn't/don't know if the 6v distributor, coil, plugs, wires, regulator, etc would switch over easily? What will I have to do about all that stuff?
 
Distributor, points, condenser, and plugs don't care if it is 6 or 12 volts.

You will either need to replace the coil with a direct 12 volt (no resistor required) coil such as NAPA IC14SB or add a 1.5 ohm resistor between switch and input to coil. Alternator will be negative ground so -- on coil goes to side of distributor

6 volt starter and solenoid should work on 12. Starter will rotate same direction regardless if positive or negative ground.

What regulator? Hopefully your alternator has internal regulator.
 
Hey guys, I messed up when I first posted this: the diesel tractor had a 12v generator after all...

I was sure I remembered an alternator, but I was wrong.

So now I have a 12v gen, modern 12v car battery. What do I need to do to run that stuff on the gas engine from the 640, originally 6v?
 
(quoted from post at 22:01:53 02/15/18) Hey guys, I messed up when I first posted this: the diesel tractor had a 12v generator after all...

I was sure I remembered an alternator, but I was wrong.

So now I have a 12v gen, modern 12v car battery. What do I need to do to run that stuff on the gas engine from the 640, originally 6v?
ame as what rvirgil_ks said, except you will need the 12v VR to go with that generator.
 
You should be able to unbolt the 12 volt generator off the diesel and bolt it right back on the gas engine. The regulator and wiring should already be there to run it. I would get a 12 volt coil that requires no external resister. There is a little block that has 2 bolts with nuts on it that has wires stacked on both sides of it. One side is always hot and the other is hot with the key on. The side that is hot with the key on is where you need to attach the wire that you need to run to the coil. It shouldn't cost any more than a new coil and a piece of wire and some connectors. Depending on which diesel air cleaner you have you may be able to find longer pieces of hose to adjust your air cleaner tube connections. I don't know if the diesel tank brackets are the same as a gas or not.
 
My 641 is a mutt. It started out as a diesel and was changed to the 134 gas. As you know now, the diesel came originally 12 volt. If yours was original the lights, starter and everything would already be 12 volt. I would definitely leave it 12 volt.

Mine has been changed to an alternator, but I love the quick starts.

Not only has mine had a engine transplant it also had a face lift to the 841 tin.

standard.jpg
 
That's a good looking tractor Scott.

I got everything together, and it works! I needed some new points, but the old gasser runs great! 54 pounds of oil pressure at 1200 rpm, cold! I've found signs that the engine is a very recent rebuild. I'm having a little trouble getting my idle down, and with the throttle linkage in general, but I'll figure that out.

The biggest problem is that the battery doesn't seem to be receiving a charge. The generator is charging, reads 14v or so, but the battery only reads just over 12. Unless the regulator turns the charge current off when the battery is fully charged, it seems I have a problem. I followed a combination of wiring diagrams (6 volt stock, 12v 1 and 3 wire alternator conversion) to get to a point where I feel reasonably confident that I have everything hooked up right, so I'm leaning toward the regulator being bad. The regulator probably wasn't bad when I got the tractor though.. it had been run and used regularly until the engine blew, so that gives me some doubts. During the rewiring, I tried to install the ammeter from the 6v gas tractor. I assume I wired something incorrectly, though I followed the diagram, because when I hooked the two wires to the two studs on the ammeter, current passed through it, jumping the battery to the starter. The engine started turning over, so I tried to rip the wires out, but they were already burning up, burned/cut into my hands, and the engine turned over for about three seconds before it slowed and then stopped, as I ripped the wires out with a wrench. I think the current probably destroyed the ammeter, which failed, finally breaking the circuit to the starter, but that's just a guess. Could that event have also damaged the regulator? How do I test the regulator?

Thanks guys
 
Not all-inclusive tests, but you can verify that the contacts have continuity when closed. Further, you can connect a variable voltage power supply from BATT to VR Ground and verify the cut-in & cut-out voltages (open/close of cut out contacts). Similarly, to verify Field control open/close, but here you apply voltage from ARM to ground. Goor idea to verify that VR matched generator with regard to type "A" / type "B", i.e., internally supplied field or externally supplied field.
 
I assume the generator and regulator are a match, they both came off the same machine originally, and it was being used. So there is a cut off voltage you're saying though? The regulator shuts off the charge to the battery at a certain point?
 
(quoted from post at 11:24:50 02/24/18) I assume the generator and regulator are a match, they both came off the same machine originally, and it was being used. So there is a cut off voltage you're saying though? The regulator shuts off the charge to the battery at a certain point?
do not say shut off charging, rather, reduce it to a smaller and smaller value.
 
(quoted from post at 00:18:16 02/25/18)
(quoted from post at 11:24:50 02/24/18) I assume the generator and regulator are a match, they both came off the same machine originally, and it was being used. So there is a cut off voltage you're saying though? The regulator shuts off the charge to the battery at a certain point?
do not say shut off charging, rather, reduce it to a smaller and smaller value.
owever the cut out contacts will open when the generator out put becomes so low as to allow the battery to apply a reverse current back into the generator. This is to prevent discharge of battery either when engine too slow or as it is turned off or stalled.
 
So I've been running this tractor for a week now, including lots of cranking, attempted starts, though relatively little actual driving time, as I tune the carb etc. It's getting harder to believe that the battery isn't charging.. It hasn't yet shown any sign of reduced power. I shut down in the dark last night though, and left the light on while I turned the key off. In an alternator setup, when the alternator stops turning, the lights dim. It's a simple way to determine whether the alternator is charging. The light didn't dim when my generator stopped turning last night. Is that confirmation that it's not charging, or is that not a good test for a generator setup?
 
The_Workmaster,
At this point, a simple Multimeter is your friend.
Measure the voltage before you start and then after it is running for a few minutes at mid RPM's.

It is really amazing how many starts a 12 volt battery can give without being recharged.

Also, my belief is that a generator system does not charge much at idle. So if you idled the tractor down, then turned on the lights and then turned it off. The lights would not dim much more because you were already in a discharge situation. The generator at idle could not produce enough charge to power the lights. I believe a better test would be to pull the lights on at idle and rev the tractor to say 12-1500 RPM's. If they brighten up, then it's charging.
IMHO
Keith
 
Well, it seems to be a bad regulator. I unscrewed the cover of the reg, checked for current at each terminal, checked for ground, everything was good. Jumped the small middle terminal wire directly to its corresponding post on the generator (field I think) to eliminate a bad wire, and no change. I then manually closed one of the contacts, the job that the electromagnet is supposed to do, and the light immediately brightened, it was finally charging. Let go and it dimmed, simple as that. The other contact was sparking very lightly while closed the whole time, doesn't look right. I jumped current to every different piece of metal in the regulator, and nothing made those magnets pull.

Guess I probably destroyed the winding of one of those electromagnets when I shorted the system last week, bummer. I'll have to order one and wait! Bad timing because it's preventing me from installing the hood and therefore the loader.

Anyway, thanks for all the help guys!
 
Oh, hm, interesting thought..

What's the advantage of an alternator setup? I see the regulator right on this site is very affordable, slightly cheaper even than a good used alternator, and then I have to make a bracket or two and rewire. There must be some disadvantage to the generator?
 
JMOR, the cheap way would be to use everything he has and add a new voltage regulator and ballast resistor. And that?s very likely what I
would do myself.
 

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