Exciter wire.. how do i know if i need one??

i'm doing a complete rewire of my 50 and just finished up the ignition and starting/charging system.. in the instructions it says i may need an exciter wire installed. my question is how do i know if i need one or not?? i'm using an american auto wire kit, and the engine/trans came out of a 73 chevy van. it has an HEI ignition.
any insight to this would sure be appreciated..

 

Jim
I think what's being talked about is the exciter wire to an alternator. Whether you need one or not depends on the alternator used.

 

standard gm internal reg alt will need one.aftermarket one wire alt will not.

 

You also do not use it if you are using a GM generator.

 

sounds like i need one, the alternator is off the donor vehicle, which was a 73 chevy van. thanks for the input guys..
just got off the phone with aaw, they pretty much said the same thing..

 

ok, i need some help here... i went to three different parts stores and no one knew what i was talking about, needing a exciter wire or diode. is this something that you just have to get the diode and solder it in line from the alternator and ign. switch??

 

just take the wire that is the exciter and attach it to the hot lead on the Alt plug. you can get a hot lead to the Alt from the starter or the starter, you can run the full wire but jumping it will do the same job and eliminate one more wire to short out on the exhaust.

 

I think want SS is trying to tell you that since you have HEI , you will have an unused small terminal on the starter solenoid, the one on the outside away from the engine. You can use this terminal to excite your alternator, as it is only hot when the engine is cranking and then disconnect as soon as you let off the key, so there is no feedback problem requiring a diode. Just run a wire from there to the alternator plug.

 

that works?
i like to run a wire from the ignition switch through a light bulb, then to the alternator. the bulb will work like a diode and give you the extra benefits of a "key on" indicator and a charging system idiot light.

 

Thanks for clearing it up. sometimes its just easier to do it than explain it.

 

i like this idea.... think i'll use it.

 

Actually no it won't. I naver ran an exciter wire until i bought the Pusher from rocky and it had an exciter wire on it. That is 40 years without give or take.

If you don't have an exciter wire you will not show a charge on your volt meter until your battery needs to charge, that usually doesn't happen until you rev it the first time.

 

As PnBr implies, The standard GM SI-series or clone alternators can be run as 1-wire, 2-wire or 3-wire setups.

For a 1-wire, run a pigtail wire from the #2 sensor terminal directly to the battery output terminal. The #1 exciter terminal is left open. As mentioned, without the exciter terminal connected, you sometimes must rev the engine a bit to get it to start charging from residual magnetism in the alternator as mentioned.

For a 2-wire setup, again run a pigtail from #2 to the battery output terminal. The #1 terminal is then connected to the ignition switch thru a bulb and/or resistor in series as mentioned above.

For a 3-wire setup, run a wire from #2 to some remote circuit location to sense voltage at that point. The #1 terminal is connected like the 2-wire setup. The 3-wire is allegedly the best setup to keep battery properly charged or so it's claimed.

Jack E/NJ

 

Jack explains it well.

I replaced my one wire alternator with an ac delco I had from an ot car Saturday morning. I'm running the 3-wire hook up and it seems to work the best. I ran the wire from #2 to the main power wire, from the battery, where it attaches to the starter. My battery is located in the trunk and with a multimeter I'm getting 14+ volts. With the single wire I got a little more than 13 volts.

 

light bulb trick works two ways, it stops the charge when you turn off the ignition and it is also a "dummy light" if the alternator stops working.