GM alternator wireing info needed

~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.], 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 startor] 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 #1terminal 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 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.

Here is a link on YT's articles section, explaining the conversion from 6V 10 12V...perhaps this can assist you...

Link

good luck,
tom

1) The big output alternator terminal (assuming its a GM SI-10) goes to the wire that used to be connected to Bat on the Voltage Regulator. It should be at least a 12 gauge, but a 10 gauge on the high output alternators, but I always just use and recommend a 10 gauge to be over safe and cautious. It is the main power feed wire to charge the battery. Its connected to the load (non battery) side of the ammeter or non grounded batt terminal if it has no ammeter.

2) The alternators 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 above.

3) For the alternators little 1 or R side terminal, run a 14 or 16 gauge wire from the ignition switch or similar electrical point (which is HOT ONLY when ignition is turned on) and in series with it, I use a 5 amp (or slightly larger depending on what your store has) 50 volt (minimum ratign, many go up to 400 volts, but almost any as long as over 25 volts and a few amps would work) diode 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 works fine and protects the regulator and diodes. 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 (1 R lil terminal per above) and positive anode end to the switch. Again, the ratings are not that exact but about any diode over a few amps and 50 volts or so and zero up to 10 ohms resistor works, but I prefer at least 5 ohms preferably 10 to limit current and protect the diodes. Dont forget to change the battery to negative ground and the coil (unless its an internal ballasted coil) 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. In the event you have a mag and not a battery powered coil ignition, whats referred to as the ignition switch above, can be replaced by another switch or circuit which is hot ONLY when the tractor is operating.

If you want to continue using the 6 volt coil if you have a coil and not a mag ignition and not a Wico Distributor, you have to add in series with and before it a Current Limitign Voltage Dropping Ceramic Ballast Resistor which is around 1.5 to 1.8 ohms and 25 watts power rated. It drops approx 6 volts leaving the remaining 6 across the coil as it was designed for. Again, unless the coil is internally ballasted (which I dotn think yours is since its a 6 volter) wire it with its lil + terminal gettign power from the load (non ignition switch) side of the ballast and the - terminal going to the distributor. Change any light bulbs to 12 volters also.

Good luck Ol John T in Indiana

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