I said I used 8GA for the 95 Amp and not a 130 Amp.

 

yeah I know... I was looking back at what Dyoungen posted about the Taurus alternator being 130 amps. I was looking online and he is right the 93 Ford Taurus puts out 120-130 amps depending on the alternator. I figured that the Taurus is fairly common and there is a place that rebuilds alternators by me for $35-$45 with core (I have done business with them many times and have never had a problem with their work). I figured that I could spend the same cash and get the higher output. But I still need to know if i need anything other than the alternator and heavier 8ga wire for the upgrade??? Also looking at putting in a new electric brake control module so i can use trailers with e-brakes... Thinking the more I have the more I can put out. Also does the 3G require more HP to run. I have read that there might be a small increase in power needed from the engine to run such an upgrade..? Looked into running HHO on the engine but decided that it's probably a crock and a waste of time...

 

With a 130 you need more than an 8GA wire, maybe a 4GA.

It takes power to make power. The more power an alternator can produce, the more power it will take from the engine. This is why performance companies sell pulley kits, slow the alternator down and it will draw less power from the engine. Back in the early 1980’s Jim Vance of the Gates Rubber Company invented serpentine belt. The wider serpentine belt transmitted more power to the alternator, allowing for higher electrical output. However all belts have their limitations.

a single V-belt can only generate ~95amps before it will slip.
a 6rib belt can only generate ~180amps before it will slip.

 

There are other 3g alternators that will work. I just happened to find this one for a taurus with the right size amount of output. The early 90's fords had the 3g with 130 output, just not sure which ones will work. I tried asking about an alternator with 130 amp output and the sales guys get this glazed look and ask what's the application. If your like me, applications don't apply.

 

The 3G has an internal regulator.
I can take some pic's of mine or you can look here: http://www.fordfuelinjection.com/?p=75

 

Which motor do you have in your '87 F-250?
If you have the dual A.I.R.pump bracket, the 8.25" center to center from a 1991-92 Sable/Taurus is the correct application.
You will need to change the pulley- insert a washer under the V belt one to keep it from rubbing the case, tap the adjuster hole to 3/8-16 and straighten the adjuster arm a little with a hammer so it only has 1 1/4" offset.

FYI, I bought an Autolite A7761-5-7 off Ebay for under $75 w/ free shipping and no core.

 

Thanks ArdWrknTrk! That link was great. I don't know if this modification has already been made since my dad has the truck right now but will be doing this mod soon (if it needs done)... I figure i can find what I need at the local yard or just pull and buy a rebuild like I said earlier...

 

Correction!

I'm brain dead, if you have an '88 you have fuel injection and a serpentine belt.
You don't need to change the pulley and find a power source for your choke like I did...

BTW, I bought the installation harness from Ryan McCormack there @ Ford Fuel Injection. It fit like a charm and came with concise instructions.
Truly "plug 'n play", the only modification you have to make is to strip and crimp the one green/red wire. (worth it to me, since I bought an alternator and didn't have a donor to scavenge the wiring from)

 

OK so I had to bring this post back from the dead just to share what could have been the problem...

After having a intermittent battery light forever I did a 3G swap on my truck. I got lucky and found a 130amp unit that was "refurbished" from O'Reilly's at the junk yard... got it for $20 i think... Waited until my buddy was working and he bench tested it, was good but had a bad bering... He replaced it with a new one for me!

FYI, if anyone needs to know for 87-91 300 I6's you can use a alternator out of a ford taurus 3.8L. It will be the 130amp unit and there is a secondary location you can bolt it into without any grinding at all... You'll need to swap the smaller (origional 2G) pully onto it so the origional serp belt will fit. Only mod will be drilling and tapping the top bolt hole on the 3G alternator for a larger bolt...

Anyhow, I was having the intermittant battery light; this also caused ALL my truck lights to dim... I mean ALL of them! I assume it was one of four problems below #1 being the most probable...

1.) Bad ground: Solved by adding another ground cable to the fender wall off the battery after 3g swap. Don't need the 3G swap to add the extra ground cable and fords are known for this problem so if you are reading this you might want to add a extra ground cable for $5-$7...

2.) dead short: this is when a "hot wire" is grounded... Solution: After getting all my 3G stuff I decided to add a extra fuse box to run all my accessory power through for my air horn, electric trailer breaks, Acc wire to 7 pin, and fog lamps... The box I have is for a hot wire off the battery and then you can lead power off 6 different posts to your accessories. Re-running my wiring through this fuse box could have solved a dead short from one of the accessory wires. It also allows a fuse to blow if i get another dead short... saving me from looking through all the wiring on my truck and narrowing down where the problem is.

3.) Bad alternator capacitor. Solved by either replacing with new capacitor or repace alternator with 3G like I did... (i believe it is the capacitor that reads the amp/volts and sends the signal to guage cluster???) Somebody please correct me if I am wrong...

4.) Bad alternator: although mine was tested several times at several places I guess the alternator could have been bad... solved by replacing obviously...

The things it was not is a bad battery. I didn't replace mine and I no longer have the problem. I hope this will help someone that is having the same problem and if not you can PM me. I can also give anyone who wants it, more information on how to do a 300 I6 3G swap...

 

Why don't you take some pictures and do a writeup?
Then a Mod could sticky it to the top of this sub-forum.