3G Alternator Wiring and Amperage ?

[Green76]

A local shop can rebuild me a 3G that will put out 180Amps for $125;D. I currently have the stock 1G setup with separate regulator. I also have HEI. Electrical wiring is not my specialty. Currently, I have a stock guage cluster with ammeter in the Bronco, but have a rebuilt cluster in a box on the shelf that has a voltmeter installed in it that I could install. Wiring under hood and frame has all been replaced by the P.O., but the wiring under dash is still pretty much original and in good shape. I figured this alternator would be a good upgrade and would be nice to have if I ever get around to installing a winch and stereo. My question is, what concerns should I have with my wiring and how should I wire it?

 

[70_Steve]

Here's a link to a tech article on oldfuelinjection.com about how to install the 3G.
http://oldfuelinjection.com/?p=75

Wiring isn't too bad. The 3G is a 2-wire alternator the way most hook it up. The output of the alternator gets hooked to the positive battery cable. This is easiest done by actually attaching the wire to the BAT+ side of the solenoid. The other wire is a Hot-in-run wire to 'turn on' the alternator. In the stock wiring harness this would be wire 904, a Green w/Red strip wire that connects to the stock voltage regulator. You said the PO replaced the wiring under the hood so look for the wire attached to the S terminal on the voltage regulator. That wire should have 12 volts with the ignition key ON.

Cap off the big Black w/Yellow stripe wire, or whatever wire is on the output of the old alternator. The ammeter will no longer function. Might consider installing the gauge cluster with the voltmeter.

Also a consideration is the pulley to drive the alternator. The stock v-belt pulley doesn't have enough surface area to drive the alternator when it's putting out a significant amount of current. I have a 130amp 3G with the old stock pulley and it always squeals. You can buy a larger diameter pulley. Of course this isn't a problem if you have a serpentine belt.

Pic courtesy of Viperwolf1!

 

[Green76]

Thanks Steve, Any ideas where I can pick up a bigger pulley?

 

[malonejy]

Your local shop doing the rebuilding probably has pulleys that they will put on for you. You can also go with a dual groove pulley. Then you essentially double the contact area. That's what I just did and finally got rid of the squeal.

 

[Green76]

I have a double groove pulley on it now, but only running a belt on the inner groove. How would I route the outer most belt? Dumb question I know, just want to get it right.....

 

[malonejy]

I simply ran a longer power steering belt. I'm sure it's not the cleanest setup, but I finally got rid of the squeal. As 70_Steve noted, you'll probably only get squeal if your actually drawing a large amount of amps from it. Mine never made any noise until I actually started to run more electric accessories.

 

[Green76]

So, did you wrap the water pump and the crank pulley? My outermost alternator pulley currently aligns with the power steering pulley that wraps around the crank and water pump. If I ran the longer power steering belt, would it still wrap the crank and water pump pulleys or just touch the top and bottom of them? The crank and water pump have to be wrapped (large contact area) don't they....I don't quite comprehend....

 

[malonejy]

In short Yes. I have a really long belt that goes around the crank-alt-water pump-pwr steering. On that belt, you are correct that there is less contact area with the crank and water pump pulleys. I currently have no squealing so it doesn't appear to be slipping. And yes I know it may not always squeal when it slips before someone too smart chimes in I should add that I'm not running a mechanical fan so I don't have the added friction of spinning that. The good thing is, these are all easy things to mess around with that don't cost too much to try different configurations. Just don't ask me how much $$ I've spent on belts in the last six months trying to get it dialed in