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alternator 5.7 vortec in squarebody

6K views 7 replies 5 participants last post by  75gmck25 
#1 ·
so the plug in from the squarebody is a little bigger than the vortec alternator plug in. on the new vortec alternator it has the single power wire and then two wire plug in. i have the pig tail from a 5.7 vortec. how would i connect it to the squarebody plug in? is it going to be an issue? the wire gauges are 2 different sizes from the squarebody and the vortec.
 
#3 ·
Yes. The original plug in for the alternator is a big red wire with a smaller gauge brown wire. I have a vortec 5.7 with edelbrock intake and carb. Serpentine system as well. The alternator for the vortec is different. Smaller gauge wire and a smaller plug in. I cut myself a couple inches of wire for the alternator to keep. Was wondering if I could butt connect them together or something.
 
#4 ·
I’m running 2 in a square. Overkill yes. But spent years plowing with the old weak single and had enough of it. Now one runs the main system and the other runs the plow, lights and my radio only. I couldn’t get the original square wiring to operate the system correctly. I added a 40 ohm 100 watt resistor into the wiring on each alternator circuit along with charge lights so it acts like the original system. Light on with just the key on and goes out when it’s charging. I’ve been running it for a couple years like this now and wouldn’t ever considering going back.


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#8 ·
The alternator wiring for my '75 square body is quite simple, and your truck probably has a similar setup. It sounds like you are using a CS130 alternator.

For stock setups the large red power wire on the BATT terminal runs down the valve cover, through a metal tube behind the exhaust manifold, then connects to the lug on the starter. However, you can also connect it to a power junction mounted on the firewall (like the newer GM trucks), or you can run the wire directly over to the battery positive (which is what I did). The stock wire is probably 10 gauge, so you have to upsize to at least an 8 gauge when you use a higher output alternator. If you use 8 gauge you can splice in a 12 gauge fusible link to protect from overload.

The two conductor plug has the sense wire and the exciter wire. On a stock truck there is enough resistance in the sense wire from the wiring and the alternator light, so you do not need to add a resistor. I assume it should also be enough for a newer alternator. The exciter wire connects to the ignition switch and turns the alternator on.

All you need is the adapter from an earlier post so that you can connect the sense and exciter wires from the truck to the same wires on the new alternator. I think the newer alternator has four wires in the connector, so two will not be used.

Bruce
 
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