I've seen the swaps with the second gen Alts but they will not physically fit my Rx2. I have a first gen alt with internal reg that fits. I installed it, unplugged the regulator and ran a 12 volt positive from the plug to the cross of the "t" plug on the back of the new alternator. I started the car and am getting 13 volts+. I don't know much about wiring but I have read that I am supposed to jump wires at the voltage regulator. Looking at the wiring diagram I see things are connected to the VR so I am assuming there is a need to jump stuff there. Also I have no idea if I need to jump, connect to, or just abandon the original plug and leave it be.

IWhat do I jump here. I've connected to the black 12v+ wire to the first gen alternator

What do I have to do to this plug. it has 3 wires

 

I found a link for you. I searched for rx7 alternator upgrade. Alternator upgrades - AusRotary
I remember doing this different on my rx3 race car. The key was knowing what the wires did at the alternator plug. I found that one wire was supposed to ground or power the dash light "L" terminal. The other wire seemed to turn it on
and make it charge. I didn't have a dash light in the race car. If i fired it up with nothing hooked up at the plug it wouldn't charge. If I touched one of the wires at the plug to power it would start charging and stay that way until I turned it off . Just a momentary touch to get the field energized. not power all the time.So I got the bright Idea to just hook it up to the starter solenoid wire. When I started up the car, it started and kept starting. there was no way to shut it down. I had to pull the battery cable to get it to stop. The alternator was sending powering up the starter, keeping it engaged. I ended up putting a one-way diode inline with that starter wire and it worked. it worked for years that way. the alternator needed to be turning for the field to stay energized and the cranking speed was enough to do that. I think that if you do a little searching you can find out how to do it the right way. Maybe that link will help. I have seen it done.They cut the wires at the regulator plug and twisted 2 or 3 together. It was a real hack job.

 

I know there's some old threads on here about this very topic, because I did this same thing 37 years ago. Might even have started the thread, it's been too long. I could try to dig around for it...

 

https://www.rx7club.com/old-school-o...rx-2-a-314014/