I have unsuccesfully searched this forum and the 73-79 forum looking for information and tips on how to add/replace a "high" output alternator for my 1978 F100 with the carburated 300 engine. I have a relatively new alternator, but it puts out only about 50-60 amps. Since I have been adding accesories (stereo w/amp; fog lights, etc) I need a higher output: I will be really happy with a 90 amps alternator (I don't think I will need more than that).
Did Ford (or anyone else) ever offer a "stock" 90-amp alternator that is a direct swap to our 300 engines (carburated) and wiring harnesses. I have read about the 3G one-wire alternator options (130 to 200 amps), which I really don't need and would rather go with something that is less involved (I don't want to hack or mess too much with the original wiring of my truck). Any tips, leads and/or links to how-to-procedures to have a 90ish-amps alternator will be greatly appreciated.

Raul

 

Autozone carries 100 amp alternators for '73-'78's for as cheap as $75.

 

That would be with a 6 1/2" case where as some came with a 5 1/4" case but you'd only have to swap the pulley if you have the smaller case. For Valucraft 100 amp alt part no. 73031 ($75) for Duralast 100 amp alt. part no. DL73031-6-9 ($100).

 

fordflaresides:
Thanks for the info. I just visited the Autozone across the street from my work and they have the Duralast 100-amp alternator in stock ($100 with core). As you mentioned, it is likely that I will have to swap the pulley.

Before I forget, I read somewhere else that upgrading some of the alternator cables (to ticker gauge), like the batt. and ground cables (?) was a good way to enhance the overall efficiency of the alternator. Has anybody here done this? I believe at least one of these cables (that goes to the regulator) has a built-in fuselink; what should I look for as far replacing this fuselink and what rationg it should have? If I upgrade some of this cabling I certainly don't want to miss a critical thing like this. Thanks again.
Raul

 

Hey Raul,

I just finished doing the G3 alternator swap/upgrade in my 94.

There are a few things that you should consider and plan for before you jump right in and start doing the upgrade.

First, try and do a "Google" search using "G3 alternator upgrade ford". There will be some really good installation directions and maybe there'll be directions for your year truck.

I too was experiencing the poor alternator performance to the extent that I replaced 4 N*P*'s that had various problems and got fed up replacing them.

I purchased my 160 amp alternator and all associated wiring from Ryan @ www.fordfuelinjection.com.
All of my cabling, wiring harnesses, alternator, fuse holder, fuses and shipping came to $ 220.00.
It's probably the best upgrade I've done on my truck yet.
Well worth the money and it's not hard to do.

I'm not quite sure how to up/download pictures to this site but I have some pics that I'd be glad to share with you even though my truck is a '94.

That being said......
Some considerations are........

Double and triple check the mounting hole spacing on your alternator bracket that you'll be using and make sure it'll fit !!!!
I know some of the older trucks needed a little alternator bracket "modifying" in order to allow the larger alternator housing to fit.

DO NOT use the two black with orange stripe wires from your old wiring harness WITH a 100+ amp alternator. The black/orange striped wires are NOT large enough to handle the high output from a 100+ amp alternator and will MOST LIKELY CAUSE THEM TO MELT DOWN AND, EVEN MORE LIKELY CAUSE A FIRE UNDER YOUR HOOD.
You really need to go to a cable(s) that'll handle the load.

Once you get a new alt., look (before mounting) at how the wiring will be routed off the back of the alternator.
The "automotive type" G3's cabling/mounting points toward the engine rather than towards the fender.

Double check the mounting bolts (in the holes they will be used in) and make sure they will go all the way in and bottom out. I had a problem with my brackets' bottom mounting hole being tapered and my bolt wasn't. Some serious wrenching was required to get the non-tapered bolt to work in the aluminum bracket.
Obviously a tap shoulda' been used.

You MUST have some kind of fuse protection whether it is a fuse or a fuseable link. If there were a short in the system without a fuse/fuseable link, a fire would be a definate possibility.

I'd recommend getting the smallest diameter pulley you can mount on the alternator---i.e. an overdrive pulley.
That'll keep your alternator "happy" at idle.
Since our engines "usually" don't spin faster than 4000 rpm you won't have to worry about exceeding the maximum rpm's an upgrade alternator will handle with an overdrive pulley.

There may be more and perhaps others may have more "insight" they'd like to share.
These are just some of the things I dealt with and hopefully it'll help you a little.

Let us know how it went and the end result !!!


Bob

 

I know you said that you dont want to swap to a 3G alternator because of wiring issues, but those are old wires, and they arent too thick.
Its a good idea to upgrade to a 160-170Amp alternator, and better wiring. especially if you have a stereo.
I just got 2 3Gs from the junkyard yesterday, and plan to swap one in, and keep the extra as a spare for now.
Optikal Illushun and I went to get them. Under $15 each with tax and core charge. Not too bad compared to over $200 new!
About the wire upgrades, thats usually called the "Big 3 upgrade". i will be doing that at the same time.
here are a few links to take a look at.
Big 3 Upgrade: http://forum.sounddomain.com/ubb/ult...5;t=007801;p=6
3G wiring harness: http://fordfuelinjection.com/index.php?p=67
3G install: http://www.fordmuscle.com/archives/2...ce/index.shtml
there is also another How-To-Install on this site, but i cant find it right now.

I hope some of this helps.

 

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