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Discussion Starter · #1 ·
Hey guys, it's been a really long time since I've been on here. Hope all are doing well. I have a little issue that I could use some advice on.

I recently installed a 100amp alternator on my 87lx, and it still has the stock 3 wire plug on it with the fuseable link in line to the solenoid. I would like to rewire this thingamajigger with heavier gauge wire and an in line fuse (think 120-140 amp). I know the easiest thing to do is just switch to a 3G alt. but I just bought this one for a really really fair price so I'm going to make it work. I want to upgrade the wiring as everything I'm currently running is electric, plus I'm getting ready to install an electric waterpump and I'm using two batteries so I feel this is the weakest link of the wiring system to date as everything else has been redone mostly with welding wire and thick gauge awg.

So is it feasible to disassemble the factory pig tail connector and solder in say.....two 8 gauge wires to splice into one 4 gauge wire into a 140 amp fuse and then on to the starter solenoid (or disconnect switch)? Or does anyone else have any other ideas?

The help is much appreciated.
Jeremy
 

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Hey guys, it's been a really long time since I've been on here. Hope all are doing well. I have a little issue that I could use some advice on.

I recently installed a 100amp alternator on my 87lx, and it still has the stock 3 wire plug on it with the fuseable link in line to the solenoid. I would like to rewire this thingamajigger with heavier gauge wire and an in line fuse (think 120-140 amp).
Manufacturers use fuse links for good reason. If you insist on using a fuse, use the best stuff you can get.

Single wire in open air requires #6 or #4 for 100 amps continuous, depending on insulation and environment. You are not likely see a voltage drop change you will notice because the wire is so short in length, the real issue is thermal. Odds are what you have is already enough, but the high flex wire here is good:

McMaster-Carr

Number 4 copper has .00025 ohms per foot, so the voltage drop is 0.025 volts per foot at 100 amperes. With a five foot alternator lead #4 AWG would drop 1/8th of a volt at 100 amperes.

The heat in the wire would only be 12.5 watts distributed over the 5 ft length, so it would stay cold at 100 amps.

The largest voltage drop and heat issue by far will be at connections, including fuses. This is why I think extra connections at fuse holders is a generally bad idea. The fuse link really is for battery fires, and they probably size it to fail at a few hundred amps. The fusing current of a number 10 copper wire link is 333 amperes.


So is it feasible to disassemble the factory pig tail connector and solder in say.....two 8 gauge wires to splice into one 4 gauge wire into a 140 amp fuse and then on to the starter solenoid (or disconnect switch)? Or does anyone else have any other ideas?
I'm not sure I know what you mean by pig tail connector. Isn't the 100 amp lead a single lug terminal? Or is it plug in?

What size is the stud or terminal? The actual connection usually is the hottest point.
 

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Discussion Starter · #3 ·
I'm not sure I know what you mean by pig tail connector. Isn't the 100 amp lead a single lug terminal? Or is it plug in?

What size is the stud or terminal? The actual connection usually is the hottest point.[/QUOTE]

Hey thanks for the reply man. That is some really good information to know as wiring is indeed my weak area.

The 100 amp connector is a plug in harness hence my redneckism of "pig tail" lol. That's the problem. If it was a one wire deal, I would never have had any qualms about the wiring. it's basically just the stock foxbody alternator hookups. I need to run the alternator wiring to the disconnect switch at the back of the car and there's where the trouble spot is. The wires on the factory harness are (I believe) two 10 gauge wires into a 14 gauge fuse link, and 14 gauge straight to the starter solenoid.

Running it to the back of the car, obviously larger wire is needed but I'm not sure how to make that happen with that dinky little plug and 10 gauge wire on the factory harness. I know the 3G swap would solve this deal all together but like I said, I got a pretty solid deal on this alternator, and I've never been one to back down from a challenge haha. Any ideas, my friend?
 

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Discussion Starter · #5 ·
Why run the alternator wire to the back???

Battery Wiring
Well......I didn't want to run it to the back but it seems somewhere along the road I had read that in irder to be nhra legal the alternator to positive battery wire had to be directly wired to the battery disconnect switch so there would be no chance the car could run off the current being created by the alternator. Yeah, I didn't quite get it either but I wanted to make sure I was within the confines of the rules.

Check the wiring diagram in this thread. The switch will be mounted on the back bumper or maybe in close proximity to the license plate (haven't decided yet). So that's why I was curious about this because everything works perfectly with the car as is right now.

Can anyone elaborate on this?
 
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