FJ40 upgraded alternator suggestions?

[CardinalFJ60]

I’ll need an alternator sometime soon for the F40 (‘77). I have lights and winch and maybe like 2000w of stereo amps.

What’s the new hotness? Stick with Externally regulated? Rewire to internally to have more options? No, I haven’t done the math, but 45a ain’t gonna cut it

 

[Rzeppa]

I’ll need an alternator sometime soon for the F40 (‘77). I have lights and winch and maybe like 2000w of stereo amps.

What’s the new hotness? Stick with Externally regulated? Rewire to internally to have more options? No, I haven’t done the math, but 45a ain’t gonna cut it

You don't necessarily need more alternator, you need more battery. When I built a gigantic stereo for my '76 '40 I added a big honkin' marine battery and an RV isolator. Worked great with stock alternator and external regulator.

 

[74fj40]

You don't necessarily need more alternator, you need more battery. When I built a gigantic stereo for my '76 '40 I added a big honkin' marine battery and an RV isolator. Worked great with stock alternator and external regulator.

This really is only a partial solution. Just because the battery can support the additional amperage being drawn, doesn’t mean that the alternator will sufficiently charge it after the fact.

I was able to install a 12SI delco alternator into the stock bracket on my F engine. I used some spacers on the engine bracket side and the adjuster bracket bolted right up. 90ish amps, internally regulated. Charges at idle unlike the later gm alternators. I upgraded the charge wire to 6awg with a maxi fuse. They are only about $100 at parts stores.

 

[SteveH]

Watch the charging rate - the factory dashboard ammeter of an FJ40 isn't rated to show 90 amps (should the alternator ever be in a position to produce full output). Just something to think about.

I didn't have issues in an FJ45 where I used a 90a self-exciting GM '1 wire' alternator, and it was nice to have a simple-to-install alternator with lots of juice.