Converting a Datsun 510 to an Internal Regulated Alternator

girl with oil can

by Thomas Walter

For those 510’s with the simple “T” style connector into the back of the alternator, this is a pretty straight forward conversion.

The Alternators

The OLD (externally regulated Alternator) had the “N” and “F” connected by the plastic “T” connector.

“N” Neutral was connected by a Y (yellow) wire.
[This is the top of the “T” connector]
“F” Field was connected by a W/B (White, black stripe) wire.
[This is the stem of the “T” connector]

The NEW IR ALT (internal regulated alternator) will have two connections, also in a T configuration like the old unit.

“S” Sense is connected to the battery (direct +12 Volts)
[This is the top of the “T” connector]
“L” Lamp is connected to the Warning lamp light.
This connection has TWO functions. By Sensing the circuit is turned on when the ignition is, it will energize the alternator. SECOND: when the alternator FAILS, and the engine is running, it will GROUND this connection – providing a ground path to turn on the “ALT” warning lamp. (you should see the “ALT” lamp glow when the ignition is first turned on, before starting the car).

How to modify the wiring

Before tossing that old voltage regulator into the trash bin
cut OFF the connector block.

Splice the W (white) wire to the Y one. (Sense circuit)
Splice the W/R (white/red) wire to the W/B one. (Lamp circuit)

This the wiring at the HARNESS, compare it to the regulator wiring, both should be the same – but some replacement units did not follow the color code. See Kelvin’s wiring diagram to be sure.

Plug the connector back onto the wiring harness. Quick, simple, painless to swap back if the need every arises.

Things to consider

The Alternator lead to the battery may be too small to handle the additional current capability of the new alternator. (Best to use a FUSED 10 gauge wire direct from the alternator to Battery).

There is also a splice in the harness, of the alternators positive lead (white with a red stripe) and the main power line from the starter to the fusebox (white). You may want check the condition of the splice, as it is buried in the harness and, if corroded, could cause problems. [From Robert Broad]

For those ’72 and later 510’s that use the electrical choke. The choke relay was powered up by the voltage that appeared on the “N” terminal of the relay. To energize correctly, the relay was designed for the lower voltage (about 6 volts) of the “N” Terminal when the engine was running. Even if you replaced the Carburetor, the relay most likely still wired up, so you may see the ALT light glow for this extra load).

Alternator Mounting Brackets

Most of the IR Alternators will have 10mm holes, so use a bracket from a later series L engine to bolt up the alternator (the 510’s OEM 8mm bolts had a habit of breaking).

Quick, simple, and clean installation. Also this allows for a quick return to a stock setup should you ever desire to do so.

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