Alternator on an A

As far as how to wire it, are you 6 or 12 volts now???

Are you pos or neg grnd now?????

Do you have a Voltage Regulator or a simple cut out relay on an existing generator????

Whats your ignition now, mag or battery powered distributor?????

And do you know if your coil is a 6 or 12 volt????? Internally ballasted or not????? and if you have any external ballast resistor???

Regardless of how the tractor came from the factory, it may or may not have been modified, so knowing the above will make my conversion directions easier. Once I know this, I can post back written instructions and post back and/or e mail a wirign diagram. The GM SI 10 is for a 12 volt systyem and negative ground, however. If you have or stay with a mag, you wont have to worry about any distributor or ballast or coil voltage concerns.

In the event you were already 12 volts and rememebr you have to change to neg ground, heres an old answer I posted before, which may or not all be applicable, dependign on the answers to the questions I posed above: Use this for preliminary guidance only, until I know answers to the above:

The big output alternator terminal (assuming its a GM SI-10 internal regulated alternator) goes to the wire that used to be connected to Bat on the Voltage Regulator. If its now a No. 12 gauge wire, it should do, unless you use any high output GM alternators, in which case I use a No. 10 just to be over safe. (Power feed wire to charge the battery). The little side number 2 or F terminal gets connected (use a short 14 jumper wire) right up to to and with the big side terminal just mentioned. For the little 1 or R side terminal, run a 14 or so wire from the ignition switch ahead of any ballast resistors(which is HOT ONLY when ignition is turned on) and in series with it, I use a 5 amp 50 volt rated diode (Typical ratign to buy, 3 amp will do, and many go up to 400 volts, but almost any as long as over 3 amp rated and 25 volts DC withstand would work) and a 10 ohm 5 watt resistor (dont really need that much wattage power rating, but they are heavy duty built and easy to wire). I have seen many with NO resisitor up to 10 ohms, but know the 10 ohm provides adequate protection. That circuit provides power to excite the field ONLY when the ignition is on. The diodes (like a one way current check valve) purpose is to prevent the alternator from back feedign and powerign the ignition so the tractor shuts off when the ignition is turned off. The diode must be wired with negative cathode (end with lil band) end to the alternator, and positive anode end to the switch. Again, the ratings are not that exact but about any diode over a few amps and 25 to 50 volts or so and a 10 ohms resistor works. Dont forget to change the battery to negative ground and the coil (if it was pos grnd before and youre just now changing), IF ITS NOT AN INTERNAL BALLASTED TYPE (If it is, dont change it) needs to be wired so the negative goes to ground via the distributior points and the positive gets power from the ignition switch, and you have to reverse ammeter leads also if your just now changing polarities. If youre changing from 6 to 12 volts, and want to use your existign 6 volt coil, you would have to add a voltage dropping current limiting Ballast Resistor in series with the wire feedign the coil from the ignition switch on its high (non distributor) side.

Let me know what you have now and I can post back and/or e mail wirign diagrams and isnstructions.

Good Luck n God Bless

Ol John T Nordhoff in Indiana

~The single wire Delco 10-SI only needs a 12 volt system using a negative ground system & is a simple bolt on using one wire from the alternator to the ammeter. It is also easier to install on a tractor without a distributor & ignition switch.

~The 3 wire internaly regulated Delco 10-SI isn't that much harder to install & is cheaper & easier to obtain [mid 1970's era GM products], & seems to work better at low tractor RPM's.

~On either Delco alternator you will need [or need to convert to] a 12 volt negative ground system [unless you opt for a high dollar 6 volt, or positive ground alternator].

~As stated above the 1 wire is the easiest to install but more expensive & is probably available from most auto parts stores . If you want to install a cheaper Delco 10-SI - [3-wire internally regulated] from a mid 70's GM car or truck, below is the complete installation instructions that I usually E-Mail out for alternator installation directions on the old 2 cyl Deere's . You will only need to use the sections that pertain to your tractor & if you are already 12 volt negative ground you can disregard that part.

..... ..... ..... ..... ..... ..... ..How to correctly install a GM [internal regulated] Delco 10-SI alternator on a 2-Cylinder John Deere..... ..... ..... ..... ..... ..... .....

~The Delco alternator you need will have the regulator terminals running like this [- -]..... ...If the regulator terminals are running like this [.l l.] with "only" the letters R & F , it is the old externally regulated Delcotron and won't work without an external regulator. The best Delco 10-SI alternators for tractor conversions are the lower output units with a 55 or lower amp output. Due to the high parasitic loads of the higher output Delco alternators at full charge they put a fairly high load on the early tractor's fan shaft drive gears.

(1)-First, the tractor must be, or have been, converted to 12 volt negative ground- [unless a high dollar positive ground, or expensive 6 volt converted alternator is used]..... If the tractor is converted to negative ground, the ignition coil should have the [-] terminal hooked to the distributor and the [+] terminal hooked to the wire from the ignition switch. If the tractor is [or has been] converted from 6 to 12 volts and the original 6 volt ignition coil is used it will need an automotive ballast resistor [in series] installed in the wire running from the ignition switch to the ignition coil [+] terminal, [ the ''ECH 1CR13'' resistor from NAPA @1.82 ohms works good,, about $14.00 ]. If a 12 volt ignition coil is used it should be the internal resisted type. If in doubt about the coil type, or whether it has the correct resistance for a 12 volt system, just measure the coil primary resistance between the [+] & [ - ] terminals. If the resistance is over 3 ohms it is probably an internally resisted 12 volt coil & will function correctly at 12 volts without an added ballast resistor. If the resistance is under 2 ohms it will then require a ballast resistor between the ignition coil and ignition switch, or points burning will probably occur.

(2)- The wires should be swapped at the ammeter to reflect the new ground polarity [if the ammeter reads backwards when the conversion is done, the wires that are hooked to the ammeter are connected incorrectly and will need to be reversed]. Only one wire should be hooked to the battery side of the ammeter, that should be the wire running to the battery [non grounded side], or to the starter [battery cable stud]. All other electrical loads, including the wire from the alternator rear [BATTERY] stud should be hooked to the [NON] battery post of the ammeter. The exception would be a cigarette lighter, it would hook to the battery side of the ammeter.

(3)-The old generator & regulator should be removed, and [ if so equipped] remove the ignition switch and light switch power feed wire [L] wire that ran to the old regulator [L] terminal. The ignition switch and light switch feed wire(s) should then be hooked directly to the [NON] battery side of the ammeter, the old [L] wire going forward to the old regulator can then be eliminated...

(4)-The alternator should be mounted so the belt is tight and not out of line. If need be, the alternator 4 case securing bolts can be removed and case halves separated slightly [not more than a 1/4" or the internal brushes will fall out], then the rear case [with stator] turned so the regulator terminals are facing out and away from engine interference or exhaust heat.

(5)-A short 14 ga. wire should be made up and run from the big [BATTERY] stud on the back of the alternator to the #2 internal regulator terminal of the alternator. That is a low power battery sensing circuit so it doesn't have to be heavy gauge.

(6)-If the alternator is over 60 amps, a 10 gauge wire should be run from the [BATTERY] stud on the back of the alternator to the [NON] battery side of the ammeter. The old wire that ran from the ammeter to the battery [or from the ammeter to the big starter cable stud on the starter] should be replaced with a 10 gauge wire capable of handling the 60+ amps from the alternator. If the alternator is under 60 amps then the wires used can be 12 gauge.

(7)-If the tractor is distributor equipped, or has an ignition switch that supplies power to the coil/mag terminal instead of ground, a 14 or 16 gauge wire should be run from the coil power terminal on the ignition switch to the #1 terminal of the internal regulator. An inline 10 ohm [2 watt + ] resistor should be installed [in series] in that wire, [that resistor isn't required for the alternator to actually operate, but is put there to protect the diode trio inside the alternator from damage due to a power surge]. Make sure the resistor isn't taped inside the harness or placed close to anything that will burn as it gets quite hot when the ignition switch is on and the alternator isn't charging [I usually install the resistor at the ignition switch]. While a little over kill, the Radio Shack 10 ohm 10 watt p/n- 271-132 works very good and is under 2 dollars.

(8)- If the system charges, and the engine shuts off promptly when the ignition switch is turned off at high RPM, that's all you need to do. If the engine won't shut down consistently, or wants to run on a little after shutdown, or you just want to make sure it will always shut down correctly, then you can install a 1-2 amp 50 volt diode [in series] in the wire that is run from the ignition switch [coil terminal] to the alternator [#1] terminal. The diode is installed in series and in addition to the added 10 ohm resistor. The diode must be installed with the polarity indicating [stripe, dot, k, +, or cath,,,,, "cathode side"] towards the alternator and the [non] marked [anode] side towards the ignition switch. That diode is placed in the system to keep the alternator form back feeding the ignition coil when the ignition switch is shut off. Not all systems need that back feed protection [depends on the ignition coil] and once the alternator stops charging after shut down there is no additional power flow [from] the alternator #1 terminal to the coil terminal on the ignition switch. I always include that diode in any conversion as it is easy and cheap and it won't have to be added later if a shut down problem arises. While again, a little over kill, the Radio Shack p/n 276-1141, 3 amp power rectifying diode will work good and is well under 2 dollars.

(9)- If the tractor has a magneto, or there isn't a functioning ignition switch, a 2 or 3 terminal oil pressure switch can be added to the engine oil pressure tap and a 14 or 16 gauge wire run from the big battery stud on the back of the alternator to one terminal of the oil pressure switch, then a 14 or 16 ga. wire run from the other oil pressure switch terminal to the #1 terminal of the internal regulator. Again, a 10 ohm 2 watt resistor should be added [in series] in that wire. A diode isn't required in this circuit due to no ignition coil interface. An oil pressure switch from NAPA [OP-6610] at [about $9.00] works good, [use terminals P & I, leave terminal S open..... ..Clooney