I have a 1986 F250 with a 5.0 302 which I recently restored two years ago. The truck was sitting for about a week. Drove it and ended up having an alternator fire. I have been wanting to upgrade the alternator anyway because of a stereo system. Being that the harness going into the alternator was ruined, and I have to change it, Can anyone recomend a bigger alternator and will the bigger alternator need a completly different harness? Thanks in advance

 

Now is the time for a 3G swap.

Search and you will see.

 

A 3G swap? not familiar with the terminology.

 

Just finished searching the 3G. Thanks for the advice sounds like what i need to do. Where wouold be the best place to get it? Will they also sell me the larger harness for it?

 

The 3g was stock on some Ford vehicles. Do some more searching to find which car or truck had the one that is easiest to adapt, and go to the autoparts store and tell them you want the alternator for that vehicle. You will still probably have to fabricate some brackets or spacers to make it fit. You will also probably have to make your own harness, or get one from the junkyard and adapt it to your truck.

If you are not up for all that, then just do a search for "high output Ford alternator" or something like that. They make them that will bolt on, but they are not cheap.

 

The 3G small case unit from a 90's 302 will bot right in. You'll just need to change the pulley, which is pretty easy. Best thing to do is pick up a 3G core from a boneyard, then take it to a local rebuilder and have it built to a 200 amp unit, complete with a new rotor, stator, and voltage regulator. There shouldn't be much of a price difference than buying a 130 amp unit parts store, and you'll get much more power. Plus you'll know exactly what you've got.

As far as wiring goes, I did it using both a reworked factory harness from the 2G with both black/orange wires from the plug sliced to an ring termnial on the charging post. I also added a 4ga wire from the charging post directly to the positive battery terminal with a 150 amp inline fuse. It works like a charm, and I run an electric fan, 1000 watts of subwoofer, driving lights, and a relay headlight system on top of all the factory goodies.

 

Can anyone tell me what the stock output is for the alternator which originally came with the truck? Thinking about going with the 3G. Have seen it advertised for over 350 dollars. Am I going with too much power for the 200 amp or will I have plenty with the 130 amp? Thanks in advance

 

I have been looking for a new harness for the alternator wiring. Does anyone have any suggestions where I can get one to fit an alternator any where from the 3g size down to the 130 amp version?

 

go here
Ford Fuel Injection
no to going with too much
it will only give you what you need

 

The stock 2G altenator put out either 65 or 75 amps.

If you google search 3G altenator conversion you can find some companies that will sell a wiring harnes to do the conversion, but you can do it yourself pretty darn easily for around $25. Read my earlier post...it's that simple.

 

You can make a much better wiring harness than money can buy.

Something often over-looked is remote voltage sensing for the regulator.

If you run a big cable direct to the battery, you can easily overcharge the battery and rapidly shorten it's useful life; better is to have a smaller longer wire for the charging wire, in order to slow things down to a more acceptable level at the battery.


So called "one wire" alternators are also good for ruining a battery and starving everything else for voltage.

I suggest you do some research on the subject before spending big money.


Sort of a condensed version = what you want is a specific "junction", where all accessories get their power, the "battery" wire goes from this junction to the positive battery post, the "charge" wire goes from this junction to the alternator, the remote voltage sensing wire goes from this junction to the regulator--either internal or external, and the various feeds to the vehicle systems start from this junction.

 

3G_Alternator