So, several years ago sometime during this build, I thought it was a good idea to purchase a March pulley system for my 454. It came with a fancy chrome 140amp CS130 alternator. Did not think much of it at the time, but now I am trying to mate it to my lectric limited replacement wiring harness and am lost. Knowing what I know now, I would have done things a bit different, but I am where I am, so hoping someone can make sense of this for me. Seems to me I need a conversion harness to make this work, but I am at a loss.
Anyone know more about this than I do? (not hard).

The black and red from the harness are straight forward, but what do I do about the 2 wire harness connector wanting to connect into the plugged alt, connector?

thank for the help

CS130 Alternator needing some wires connected.

Lectric limited wiring connectors

 

You need an adapter harness. I have a spare. PM me if you would like it.

 

You should also upgrade the size of that larger red charge wire.

 

I hate to take your harness. Thanks for the offer, but I can drop by Summit and pick one up if I can figure out what works.

Is this correct?

https://www.summitracing.com/parts/pwm-140

 

I was thinking that might be a problem.

Rather than tear apart the entire harness, was thinking I might run a parallel wire, same size to the battery and put it in the loom. Thoughts on that? Definitely don't want a bubba build, so if that is questionable, I can dig into the lectric limited harness and replace the wire.

Thanks for the help.

Much appreciated.

 

That would work.

 

I think you'll need to add the resistor, that doesn't look like it has one built in
M

Actually I'll take that back, I'm not sure if the CS130 needs it or not, I know the CS144 does and I believe the CS130 will need it but can't guarantee it does

 

That will NOT work. Parallel feeders that small are only good for voltage drop, not total load. The current will take the path of least resistance, and burn up the wire. It needs to be replaced by a larger wire, with a larger fusable link. I believe power master has these made up as well.

 

You need a resistor if you do NOT have an idiot light.

If a resistor is needed, it's probably in his harness. (Come to think of it).

 

73 didn't have an idiot light and I was guessing that what he had for a car
M

 

73racevette
Here you go. Go run these checks and get the appropriate adapters. Part numbers for you and everything:

https://www.corvetteforum.com/forums...post1600896528

 

Sure it will. The load will be divided between the two parallel paths based on the resistance in each wire. Been running the 140A CS144 on my '73 for 10 years with the original charge wire and a larger wire in parallel with it. Both wires need appropriate fusible links or other protection. What won't work correctly with parallel charging wires is the ammeter if his car as one. It will only see the current in the factory original wire and so will read low. I had that situation for awhile until I upgraded to AutoMeter gauges and replaced the ammeter with a voltmeter.

DC

 

Your larger wire is carrying the load.

 

NO- that is a fire hazard-

Fuses are RATED to pop before the wire melts/burns. If you are running a 100AMP FUSE FOR THE LARGER WIRE - THEN the SMALLER GAUGE wire could see 100AMPS as well...

When you fuse the larger wire - at the starter/battery THEN run it to the stud on the alternator- the SMALLER wire has the potential of MORE current than it can handle.
You are not really worked about the alternator shorting out- when that happens- smoke comes out of the alternator- no more power.

HOWEVER- the wire connected to the battery has a potential of 700+ amps.

Just for fun- take the smaller gauge wire - car not running- and short out the smaller gauge wire right before the fusible link. Let me know what happens!!!
NO..NO- do not try that unless you have a fire extinguisher handy...

Electricity not only takes the path of least resistance - BUT all paths!!!

 

Thanks everyone for the input. Much appreciated.

Off to Summit to get the adapter and I guess, I will have to dig into the harness and replace the small wire. Ugh.

 

Safer bet is change the wire.



This is what I did for years. If you run parallel wires of unequal resistance, and you have a fault, bad things happen.
Now we will argue about 1/R + 1/R and how it can work, but when it goes south, it is not a good solution.
Just the math to determine the joint ampacity while calculating the unequal current carrying capacity over 6' of wire boggles the mind.
Richard has shown a prime example.

 

As Richard said, electricity takes all paths. The larger wire will carry a larger share of the load. But the smaller wire will carry some of the load. It's basic parallel circuit theory. Each wire will share the load based on the total resistance in each path. How does the ammeter work? It's another parallel path. It works because it's a smaller wire and only a small portion of the total load flows through that wire. Note that the ammeter circuit is protected with fusible links. Using two parallel wires of different sizes requires that both need to be properly protected (individually) as I said (one fusible link of proper size for each parallel path). Whenever the fusible link blows on one of the wires, the other wire will then carry the entire load until its fusible link blows.

 

If you really don't want to open the new harness then run another 10 gauge wire with the same fusible link as the stock wire. Then, they are both protected the same. If the stock wire isn't 10 gauge then use the wire size that it is. I believe the stock wire goes from alternator to horn relay to solenoid so I'd try to follow the same path. This isn't the ideal solution but at least the wiring is protected.


73 had an ammeter so you need the adapter harness with the resistor.

 

Thanks, I will dig into the harness and determine the existing path. I am putting in different electrical gauges that pull from my Holley ECM, so sounds like I need to check ohms on the harness to be sure I am above 35ohms. Also need to figure out the original ignition switch/horn relay path and determine what I need to do for my application. Also need to include power for 2 relays running electric fans, power for vintage air and power for a stereo amp in the mix. I am in deep, but will fight through it.

 

You really don't have to keep the second charging wire the same size as the original. You can make it as large as you want it to be. But, the new wire needs to be properly protected with the correct size fusible link for that wire as if it was going to stand alone. You also need to maintain the existing fusible link for the original charging wire. Whether the two wires are the same size or not makes no difference when there is an electrical short. Whichever wire shorts first, that wire becomes the path of least resistance and it's fusible link will blow first. At that time the remaining wire becomes the path of least resistance and all load will now pass through it which will blow that fusible link (assuming the load is great enough at that point). The combination of the two wires does need to be able to handle the total load on the charging circuit.

Fusible links need to be two wire gauges smaller than the wire they are protecting. For example, a 10 gauge wire needs a 14 gauge fusible link.

As I've alluded to but maybe not made clear, the factory actually used a parallel path situation with one wire much smaller than the other. The ammeter circuit is in parallel with the original charging circuit. The ammeter wire is smaller but is protected at both ends by fusible links. The ammeter wire does not extend from one end of the charging circuit to the other because some brainiac calculated the length so that the ammeter would read the full current flow through the charging circuit even though it only sees a small portion of that current.

DC