I do know there are 64 strands of copper. Why I can’t find this info out is beyond me.

 

vernier calipers?

 

They make a wire gauge tool that will tell you this exact thing. You stick the wire in it and it will fit in whatever size it is. No really a complicated thing to figure out. You can also eyeball it. 2, 4 and 8 gauge are pretty easy to see the difference. In addition to that, if its alternator then its likely 4 gauge. Even if it wasnt, use a gauge that makes sense for the application. Not sure what you're in the middle of =/

 

I do not have any tools that can help out with this one. I plan on running a higher amperage alternator but I still working out what the limit is on the stock system. I’m leaning to the FD alternator with I believe is 90A. I’m running fuel injection with a electric fan. No high powered audio. I will need the dual pulley of course .

 

You'll be fine with 4 gauge. I redid my whole system on my fd with all 4 gauge. Stock is 8.

 

You can measure the diametre and check against an online chart for peace of mind

 

Not sure how much it helped, but when I installed my S4 alternator I also ran a ground directly from the alternator to the factory strut tower ground location.

 

good advise, one of the things Mazda did between the 1980 and the FD was to make that wire larger. the Fuse gets bigger too (early FC is 80a, and i think it goes to 100a?)

 

Also be careful when using newer style wire. A lot of it is CCA (Copper Coated Aluminum). Make sure to get 100% copper.

 

YES.. this exactly... i made this mistake. the wire literally turns to dust

 

good to know. I will make new cables. thank you

 

For AWG, here ya go:
8g 40A
6g 55A
4g 70A
2g 95A
so in 'normal' use you'll be ok with 6g and fine with 4g.
Abnormal use like my night trials car (600W lights, wipers, heater fan, extra inside gear all at the same time) even a 2g doesn't stress with a 110A alternator.
Sort of related: Australian Ford Falcon cars around '95 had that Mitsubishi Electric alternator which is a bolt-on to a rotary just needing a shorter spacer and a 17mm shaft pulley (same as FD) - might be worth some research for anyone needing lots of amps.