Electrical 85 1g to 3g conversion HELP!

I have something on this conversion that I found 20+ years ago.
I copied it from my old website section, 3G, 130A ALTERNATOR UPGRADE
Hope this helps.

Alternator Connections for Other Years:

On your 84 external voltage regulator, you have the following:
F, S, A, I

Unplug the wiring harness going into the external voltage regulator. Either splice into with your new wire or make a blade connector that will go into the old wiring harness. You will need to tap into two of those wires:
The F will not be used.
The S will go directly to the I on the 3G. The A will go directly to the A on the 3G. The I will not be used.

Looking at it from the 3G viewpoint:

The BAT goes to the inline fuse.
The stator connector goes to the S connector on the 3G.
The A connector goes to the A wire on the old wiring harness.
The S connector goes to the stator connector on the back of the 3G.
The I connector goes to the S wire on the old wiring harness.

The 3G has an internal fan instead of the external ones of the earlier ones. It's much more efficient, therefore, more power output.

First off, no external regulator is used on a 3G alternator. There is an excellent article in the February 2019 issue of Hot Rod magazine. I think it is available on line. There are only two wires that need to be hooked up. One is the main charge wire and the other is the idiot light (exciter) wire. If you can’t find the article let me know and I’ll try and post it here.

I am upgrading to a new 100? Amp alternator on my 84 and I am going with jegs 55510132 . I would go boneyard, but want to keep it on a quick turnaround as I don’t have time to go to the junkyard.

I need a wiring kit to go with it, is it something I can buy online or do I need to get that from a boneyard? I know it is internal reg vs my outdated regulator, what plugs would I need? Thanks guys

@Kevnic

3G install into an 85 or earlier Mustang:


I would recommend the addition of a 2 amp fuse on the Light Green/Red wire that goes to the switched ignition.
I would use a maximum of 125 amp fuse for the output wire that connects to the starter solenoid.

The prices below have changed, but this is a list of what you need to do your own wiring.
For a 120 amp circuit breaker see https://www.delcity.net/store/Hi!Amp-Circuit-Breakers/p_167861

Fuse holder from local NAPA dealer - Item#: BK 7821143 Price: $12.99
Product Features: Thermal Plastic Holder For AMG Type Fuse Rated From 100 To 300 amp.



I would use a maximum of 120-125 amp fuse for the output wire that connects to the starter solenoid. Fuses are slow blow so it would pass 130 amps for a continuous runtime without blowing.

See WWW.partsexpress.com for the fuse & fuse holder.
Fuse @ $3.90 each (need one) http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=071-952

Fuse holder @ $5.80 each (need one). http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=263-630

Check on the wire prices, they tend to change often. Copper is an expensive commodity these days.

*4 gauge black wire for needed supplemental ground @ about $1.95 a foot (use string to lay out routing & determine length).

4 gauge red wire @ about $1.95 a foot (use string to lay out routing & determine length).

4 gauge ring crimp terminals (package of 5) $3.25.

3/4 “ Black heat shrink tubing, 4ft length, $3.56

3/4 “ Red heat shrink tubing, 4ft length, $3.56

Pre-fab 4 gauge cables with lugs already on the ends are available in most auto parts stores. Look for the starter switch to starter cables.

*Keep in mind that you are not just trying to charge the battery, but power the lights, A/C, wipers, radio, etc. Each one uses chassis ground as the return path to its power source. Without the extra ground, the current flow is from the engine block to the starter power ground and back to the battery. The current must then flow through the small 10 gauge ground pigtail to reach the chassis. The secondary power ground for the alternator is a 10 gauge ground strap from the back of the intake manifold to the chassis. It is often damaged or completely missing. The 4 gauge ground wire will cost less than $5 and it will insure that there is a low resistance path for the alternator's output.