So my 79 SA has a 1 wire GM alternator in it currently that was installed by the previous owner, It has the main battery wire on it and nothing else.

I have a S4/5 alternator I want to replace it with but need some assistance on the wiring. I also want to remove the external regulator from the engine bay.

The engine harness side of the main connector has been stripped of nearly all wires so I don't know which pins would be the 'L terminal' or 'R terminal' wires.

Yes I have looked around the forums but find several differing answers to each question so would love if anyone has actually done this in the past couple of years and can advise/help out.

Questions :

1. Which pins/locations on the engine side of the mail connector are for the 'L terminal' and 'R terminal' wires. My understanding is I only need the 'L Terminal' wire

( Post referencing Terminals https://www.rx7club.com/1st-generation-specific-1979-1985-18/s5-alternator-swap-into-sa22c-questions-391510/ )

2. I don't have the auto choke working as of now and don't really need it, also not concerned with having the voltmeter working. When removing the external regulator which wires do I need to jump/bridge if any?

Thanks in advance for any answers.

 

S4 and S5 alternators get, or should get, wired differently. Which one will you be using?

FWIW in 2025 I'd see if a newer Subaru alternator can accept a V belt pulley. They are the same form factor (even though Mazda is Mitsubishi and Subaru is Hitachi) and they are more common, and typically of higher output.

By "newer" I mean newer than FC, I am thinking something from an EJ20/25 powered car.

 

I think it is from a '86 rx7, so s4. Pic of actual alternator attached (: @peejay

 

Welp, I hooked the the main battery cable, hooked the R terminal on the alternator to switched power, and unplugged the external regulator. Seems to be charging