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How to correctly install a GM [internal regulated] Delco 10-SI alternator.. (1)-First the tractor must be, or have been, converted to 12 volt negative ground- [unless a high dollar positive ground, or 6 volt converted alternator is used]..... If converted to negative ground, the ignition coil should have the [-] terminal hooked to the distributor & the [+] terminal hooked to the wire from the ignition switch.. (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 are wrong & 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 the starter battery cable stud. All other electrical loads, including the wire from the alternator [BATTERY] stud should be hooked to the NON battery post of the ammeter. (3)-The old generator & regulator should be removed & [ if so equipped] remove the ignition switch & light switch power feed wire [L] load wire that ran to the old regulator [L] terminal. The ignition switch & light 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 & not out of line. (5)-A short 14 ga. wire should be made up & 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 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 wire used can be 12 gauge. (7)-If the tractor is distributor equipped, or has an ignition switch that supplies power 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 & the alternator isn't charging. (8)- If the system charges, & 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 & in addition to the added 10 ohm resistor. The diode must be installed with the polarity indicating stripe [cathode side] towards the alternator & the non striped [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 & once the alternator stops charging on shut down there is no additional power flow [from] the alternator #1 wire to the coil terminal on the ignition switch. I always include that diode in any conversion as it is easy & cheap & it won't have to be added later if a shut down problem arises. (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 oil pressure tap & 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 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.
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