3G alternator upgrade procedures to an 85 5.0

[Supersonic G.T.350]

Thanks, did you use the above diagram? Is it correct?

[ZephyrEFI]

The only wire you need from the original harness is the green one. pull it out of the harness run it to the alt. VERY easy. The yellow wire, i just ran to the main power lug on the alternator itself.

[Unclesams_SVO]

Thanks, did you use the above diagram? Is it correct?

I did it a while ago, but that diagram looks right. I got my "mega fuse" from Napa, but they can be found on Amazon as well.

[Supersonic G.T.350]

Thanks, much appreciated!

[brianj]

The yellow wire, i just ran to the main power lug on the alternator itself.

Be a bit careful with this- it does make the alternator function, but it bypasses the load sense on the alternator. If you put a good load downstream from the alternator (say, headlights) the alternator voltage drop at the stud will be less than at the drop at the wiring harness, and the alternator will not bump up output as much as it would if it was hooked to a 12v source elsewhere. Not really much of an issue unless you run at night with accessories on, but it can lead to under charging.

[Supersonic G.T.350]

Be a bit careful with this- it does make the alternator function, but it bypasses the load sense on the alternator. If you put a good load downstream from the alternator (say, headlights) the alternator voltage drop at the stud will be less than at the drop at the wiring harness, and the alternator will not bump up output as much as it would if it was hooked to a 12v source elsewhere. Not really much of an issue unless you run at night with accessories on, but it can lead to under charging.

So Brian, all I would need to do is hook into any key on 12v source that's not directly on the alternator, right?

[brianj]

Best is the battery, but really any 12V source. I had mine tapped onto the large yellow wire in the harness, right by the starter solenoid. Right to the solenoid on the battery side would work, too. It just wants to know what the system voltage is, instead of reading alternator output voltage. If you tap a keyed source, you would not need to worry about fusing it, however. Mine ran unfused, which was probably not the bestest of ideas, but I knew i was going to be stripping all of the wiring out eventually anyhow.

[ZephyrEFI]

Sounds reasonable enough. I'm doing some rewiring this winter (if i ever get the chance), so there's no reason i can do that at that time.

[wraithracing]

I just had to wire up a 130 amp alternator on my Road Racer. I highly recommend following Brianj's advice. running the yellow wire back to the starter solenoid is a much better solution than just attaching it to the main cable on the alternator. Does a much better job of sensing the load on the entire electrical system. Seems kind of redundant, but it does make a difference. Good Luck!

[Supersonic G.T.350]

Awesome guys, thanks for the advice!