Which alternator for conversion?

The GM 3 wire is the one you want, 12SI, the 1 wire has to be rev'd up before it will start to charge.

Yer amp gauge will work just fine, unless it is broke or you just want to change it. As for the removing the neg post, yeah it will still work but that is not really a good thing to do to the internal reg of the alternator. Just use a volt/ohm meter and measure the voltage at the battery with the engine running it should be between 13-14 volts.

JohnW said:

The GM 3 wire is the one you want, 12SI, the 1 wire has to be rev'd up before it will start to charge.

Yer amp gauge will work just fine, unless it is broke or you just want to change it. As for the removing the neg post, yeah it will still work but that is not really a good thing to do to the internal reg of the alternator. Just use a volt/ohm meter and measure the voltage at the battery with the engine running it should be between 13-14 volts.

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my 12 volt conversion has the 3 wire GM.. seems to be good

The GM 3 wire is your best option... for many reasons. One they are readily available theya are cheaper than the single wire version and with a little electrical knowledge the 3 wire can and will run lights and accesories with ease. the 12SI alt is the one you want. Ill get you the NAPA, Autozone, and Advanced PT #s for both the one wire and 3 wire i just need to get to the house I also have a hand drawn wiring diagram i cam fax you. I dont have a scanner or i would post it. you can reach me at [email protected]

JohnW said:

The GM 3 wire is the one you want, 12SI, the 1 wire has to be rev'd up before it will start to charge.

Yer amp gauge will work just fine, unless it is broke or you just want to change it. As for the removing the neg post, yeah it will still work but that is not really a good thing to do to the internal reg of the alternator. Just use a volt/ohm meter and measure the voltage at the battery with the engine running it should be between 13-14 volts.

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The "take the negative cable off" thing WILL NOT!!!!! Work.
It was a valid test for generators, NOT alternators!
If everything is working correctly, an engine will continue to run with an alternator system when you disconnect a battery cable, BUT it will put a voltage spike through the system which will do damage, it may not show up immediately, but it does cause damage. On an older system with no electronics, you may not cause enough damage to matter. But with the profusion of solid state voltage regulators & electronic modules for everything from ignition to reverse lock-outs, WHY take the chance?
An ammeter or a voltmeter will tell you a lot more about the system, quicker easier & SAFER (not only the voltage spike issue but a spark near a charging battery can cause an explosion & spray acid everywhere!).
Obviously I can't stop anyone from doing whatever they want with their own equipment, but I can warn you about what can happen.
I've worked in automotive shops for over 40 years, & owned my own shop for the last 29 years. I've seen a lot of damage done by well-meaning folks who were trying to "check their charging system"
PLEASE DON'T REMOVE A BATTERY CABLE TO CHECK THE CHARGING SYSTEM!!

Ok, heres the deal..My 8n has already been changed over..The battery is old and it may well be bad. I wont know for sure until tomorrow..The tractor has a ampmeter..It reads 0 (or very close to it) all the time, except when I turn off the tractor and turn on the lights then it drops into the "negative-" just a little. I have a problem with either the alternator or battery..I can jump the battery and it will start the tractor several times then it gets to weak to start the tractor..I was wanting to know which alternator in case i have to replace it..Im gonna try a known good battery in it tomorrow morning and we'll see..Any opinions welcome :thanku:
An ampmeter on a 12v system would only show very little charge if its working, am I right on this?

KY-BlackSmith said:

u:
An ampmeter on a 12v system would only show very little charge if its working, am I right on this?

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It depends on how low the battery is. The ammeter should work with an alternator the same as a REGULATED generator, that is, you start the engine, it shows "some charge" which should gradually taper to center as you charge up the battery.

Make sure the belt is nice and tight. I just picked up a cub a couple of days ago and the PO told me it needed a new battery. I jump it and it ran like a champ for about 20 minutes. When I shut it off it wouldn't start again. Like the battery was dead. I took off the hood (PITA to get to) to find there was no ajustment left on the generator belt. Either belt streched or was too long to begin with. Put a new belt on and the battery charges find. PO has been jumping it the last two years.

Kirk