Alternator question

Kahuna

Kahuna

Well-known member
Guys
I have a GM 10 SI alternator that came on a 56 Ford I bought. But it was not hooked up. I'm posting here because there is more experience here in the Early V8 Forum for wiring assistance.
OK, On the alternator there are 3 connections: A plug that has one for the charge light, and one for the excite wire (from ignition switch circuit).
Then a larger one that goes to the battery.
My question is about the ignition switch wire and the size of the wire.
The plug wires had been cut off: The one for ignition is quite a large gauge (10) and I would like to know why?
If all this wire does is turn on the alternator, why is it such a big wire?
I've done a bit of research & haven't got a clue. Any help is appreciated.
Thanks so much
Jim
The reason for the question is that I'm trying to use an original type wiring harness.
 
Someone probably had it hooked up as a one wire alt conversion or attempted to. Hook it up with your harness and you will be good to go.
 
You have one for charging going to battery.
Another for sensing the voltage for you system going to the fuseblock or some other central part of your wiring not being switched.
Then you charging light cable being the only one needing a switched connection or the light will be constantly on engine not running..
 
The best GM alternator to run is the true 1 wire self exiting version. A true 1 wire,no regulator,reasonably priced and cleans up the wiring. They also usually have higher amp ratings then the earlier 3 wire also. Then you may run a voltmeter.
 
Thanks for the help.
Although it doesn't tell me why the wire is so large?
I'm using an original (repro) wire harness and trying to make
the alternator appear to be original (kinda). I've taken a new
regulator & isolated all three terminals to create kind of a
terminal block & then hook the original wires t that to create
the illusion that it's all hooked up. I know, kind of dumb, but that's me
Thanks
Jim
Hey Sid
How's Idaho treating you?
Best
Jim
 
Last edited:
The wire that goes to the large post on the alt. is usually 8-10 ga. as I recall the other 2 from the plug are much smaller. usually 14 on the blue and 14 ga. to 16 ga. on the pink. The blue goes to the acc. side of the key switch and the pink is for idiot light as I recall. The blue is to exite the alt. I hope this helps a little........Every things well
I'm just trying to get ready for winter up here.
Other then that just starting to put the Starliner
together that I just painted. Take care Jim.......
 
Sid said:
The wire that goes to the large post on the alt. is usually 8-10 ga. as I recall the other 2 from the plug are much smaller. usually 14 on the blue and 14 ga. to 16 ga. on the pink. The blue goes to the acc. side of the key switch and the pink is for idiot light as I recall. The blue is to exite the alt. I hope this helps a little........Every things well
I'm just trying to get ready for winter up here.
Other then that just starting to put the Starliner
together that I just painted. Take care Jim.......
Click to expand...

Sid. I'm thinking the ign side of the switch.
 
Tony said:
Sid. I'm thinking the ign side of the switch.
Click to expand...

If you attach the blue to the ign. side it will work but when you turn key off the car will keep running. That's why it goes to the acc. side.
 
I disagree with some of the wiring suggestions. The #2 terminal should connect to a NON-switched source (always hot) and as near as practical to the battery. The #1 terminal connects to a switch source via a indicator light or similar load. The BAT terminal connects to the battery. The #2 terminal is the same one you can connect directly to the BAT terminal at the alternator to eliminate the wire doing back to another source. However, this connection does not provide the remote sensing that you get with the correct setup.

As for using a dummy voltage regulator as a terminal strip, I am using the same arrangement to maintain the original look of the wiring.

Some examples of wiring:
 

Attachments

  • 2013-07-28_234924_gm_alternator_connections.jpg
    2013-07-28_234924_gm_alternator_connections.jpg
    112 KB · Views: 37
  • alternator-wiring.jpg
    alternator-wiring.jpg
    68.9 KB · Views: 41
  • chargcircuit.jpg
    chargcircuit.jpg
    19.2 KB · Views: 39
  • DelcoWiring.jpg
    DelcoWiring.jpg
    38.9 KB · Views: 32
Last edited:
I use a #8 on the output terminal to reduce resistance in the charging line, and #16's for the sensor run and exciter/ignition switch run. If you don't use and idiot light install a 10 ohm/10 watt resistor as a substitute. To my knowledge all typical alternators have an internal regulator.

I have used 10SI and 12SI Delco alternators of 55 to 73 amp sizes and now use a one-wire 63 amp unit that functions very well. Beware of off-shore units. My experience has been that their regulators are often have short-lived and sometimes non-functional right out of the box. Your local electrical motor shop can be a good resource.
 
Thanks everyone.
Jseery, the diagram & pics posted are exactly like what I have.
The plug shown in the first pic is also like I have & the wires are the same in size & color.
The red wire is quite large (10 or 12 guage).
That was my initial question? Why such a heavy gauge wire in that position.
Don't want to fry anything if using a smaller wire will create a problem
I am going to use the idiot light also.
In picture #2, labelled internally regulated Alternator, if I wire mine up like that will I be OK?
Thanks again to all
Jim
 
I again want to thank everyone for their input & help.
I think I finally have it clear in my head now
JSeery & Ross F 1 thanks so much for the pictures, VERY helpful
Regards
Jim
 
You must log in or register to reply here.
Back
Top