IH 424 Generator

Replacing the generator on a 424. Posts about converting some Farmalls from 6v to 12v convinced me it was straightforward. Fabricated the new bracket and ready to wire. But the 424 is a 12v negative ground system equipped with a generator and external regulator. After reviewing some posted schematics for the Farmall conversions it’s not clear how to proceed.

Since the alternator (Delco 10si) has an internal regulator is it necessary to remove the external regulator? Is there anyone that has performed this conversion or that can make recommendations? Here’s a link to the 424 wiring schematics.

If youre using an internally regulated Alternator, or any alternator for that matter, YOU DO NOT USE THE OLD DC GENERATORS VOLTAGE REGULATOR. It was for regulating the charge of the old DC genny NOT an alternator.

The alternators output basically wires to where the BAT terminal wired on the old VR system, i.e. it leads up to the Load (NOT battery/starter) side of the ammeter. However, when I convert from a 20 amp genny to a 30 or more amp alternator I replace that old wire (Alternators output up to ammeter) with a new 8 or 10 Gauge wire and likewise the same from the other Supply side of the ammeter to where it connects to the big battery cable, often at starter switch or solenoid.

Since youre staying at neg ground you dont have to reverse ammeter or coil leads, and if youre staying at 12 volts you dont need to worry about ballast resistor additions or coil swaps either.

Just wire the alternators big main output up to the ammeter and discard the old Gennys VR.

You do have to wire the alternators excitation circuit and use a resistor or idiot light or diode etc to prevent the tractor from running on if the ignition is turned off as necessary, but theres already a ton of those diagrams and pictures out there

John T

Resistor on the coil + 12 volt lead.

What if he has a Diesel???

The 424 is a Gas. If the link to the wiring diagram works, you can see the type at the bottom. I confirmed the tractor is wired per the diagram.

Thanks John T, wired per you post and it charges fine. No ammeter on the 424 but otherwise easy enough. I'll update the wiring diagrams in case anyone else ever has this question.