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Username Post: Generator to alternator wiring modification ..help        (Topic#133340)
59impalajp 
Senior Member
Posts: 237
59impalajp
Loc: Chile, South America
Reg: 04-13-05
06-07-06 03:06 AM - Post#948546    

Hello.
I have the original generator setup in my 59 impala that I would like to upgrade with alternator.
What is the correct way to modify the original wiring harness to change it? .
Because I will use a GM HEI electronic ignition setup, I would to know if do I need to replace the voltage regulator with an electronict type one, or should I keep the same old regulator????
Thanks.
JP
59 Impala Sport Coupe


 
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Chair City 
Contributor
Posts: 354

Loc: Thomasville, NC USA
Reg: 01-24-04
Re: Generator to alternator wiring modification ..help
06-07-06 03:46 AM - Post#948547    
    In response to 59impalajp

If you use a GM alternator with an internal regulator such as 10-S1 or 12-S1 you will not need the existing regulator.
Visit This site for some good info. The HEI will require a full 12 volts. You will have to bypass the resistance wire that feeds the existing coil.
1960 Impala Spt. Cpe. Daily Driver


 
59impalajp 
Senior Member
Posts: 237
59impalajp
Loc: Chile, South America
Reg: 04-13-05
Re: Generator to alternator wiring modification ..help
06-09-06 03:45 AM - Post#948548    
    In response to Chair City

Hello.
After some reading I end up with a solution of how to modify the existing original engine wiring harness (with generator) to accept an 3-wire alternator.
Because I don´t know much about it, I would like to share with you and have some comments and corrections if needed.
I have highlighted in red the wiring from the generator all the way to the fuse box and then to the ignition switch.
I have highlighted in light brown the wiring from the generator to the "GEN" light on the dash, that I´m planning to keep with the alternator.
On top of the page, I have drawn the typical 3-wire alternator. There, the big red connector is the "BAT" goes directly to the battery. The terminal "1" goes to the warning dash light, whereas the terminal 2 goes to the battery and is used to excite the alternator into operation.

Thanks
JP




59 Impala Sport Coupe


 
60chevcayne 
Senior Member
Posts: 119
60chevcayne
Loc: Rochester, NY USA
Reg: 02-14-05
Re: Generator to alternator wiring modification ..help
06-09-06 05:37 AM - Post#948549    
    In response to 59impalajp

That's how I did mine on my 60. Works great. As a matter of fact, I jammed almost 10 CDs on my stereo yesterday all afternoon, and had no problem starting my car right up.
60chevcayne

'57 Chevrolet 3600 3/4 ton step-side
'60 Biscayne 4-door 307/700r4
'61 Impala 4-door hardtop 283/glide
'67 Impala ragtop 283/TH350


 
raycow 
Honored Member
Posts: 18285

Age: 71
Loc: San Francisco, CA
Reg: 11-26-02
Re: Generator to alternator wiring modification ..help
06-09-06 06:03 AM - Post#948550    
    In response to 59impalajp

That's basically correct and will work as you show it. However, you can eliminate one wire by running a short jumper from #2 to the BAT terminal on the alternator.

Ray
Bacon is the gateway drug for vegetarians - Bridget Lancaster


 
59impalajp 
Senior Member
Posts: 237
59impalajp
Loc: Chile, South America
Reg: 04-13-05
Re: Generator to alternator wiring modification ..help
06-09-06 06:42 AM - Post#948551    
    In response to raycow

Ray, if I connect terminal 2 to the BAT terminal on the alternator, the built in regulator will be acting only internally.
That´s mean the amount of voltage delivered to the battery and to the electrical system will be less than that. Check THIS.

I have also another question.
Because the original electrical system was thought to work with a current of roughly 35 amps, I would like to know what happend when we upgrade the system and replace the old generator with a 63 amp 10SI alternator .
It is correct to do that and don´t worry about the increase in amps???. It is just matter of replace the generator and some cables??.
thanks for your comments.
jp
59 Impala Sport Coupe


 
Chair City 
Contributor
Posts: 354

Loc: Thomasville, NC USA
Reg: 01-24-04
Re: Generator to alternator wiring modification ..help
06-09-06 06:57 AM - Post#948552    
    In response to 59impalajp

JP, I too noticed the MAD electric article shows the No. 2 terminal connected downstream from the BAT terminal. My alternator is a 12-S1 from a 85 Impala There is a short jumper from the No.2 term. to the BAT term. I figured if it was OK with GM I would leave it like that. So far works fine.
1960 Impala Spt. Cpe. Daily Driver


 
threeimpalas 
Senior Member
Posts: 917

Loc: M'town, IA
Reg: 02-21-02
Re: Generator to alternator wiring modification ..
06-09-06 07:02 AM - Post#948553    
    In response to Chair City

Quote:

...My alternator is a 12-S1 from a 85 Impala There is a short jumper from the No.2 term. to the BAT term. I figured if it was OK with GM I would leave it like that...




Are you sure it was that way from the factory on the '85?
Mike


 
Chair City 
Contributor
Posts: 354

Loc: Thomasville, NC USA
Reg: 01-24-04
Re: Generator to alternator wiring modification ..
06-09-06 07:13 AM - Post#948554    
    In response to threeimpalas

Quote:

Quote:

...My alternator is a 12-S1 from a 85 Impala There is a short jumper from the No.2 term. to the BAT term. I figured if it was OK with GM I would leave it like that...




Are you sure it was that way from the factory on the '85?



Sure was. I bought the car in running condition. Wiring had no modifications.
1960 Impala Spt. Cpe. Daily Driver


 
59 EWW 
Very Senior Member
Posts: 1871
59 EWW
Loc: Kansas City Kansas
Reg: 08-31-03
Re: Generator to alternator wiring modification ..help
06-09-06 05:50 PM - Post#948555    
    In response to 59impalajp

Hi JP

Most people do not take advantage of the voltage sensing aspect of the internal regulator on the 3 wire alternator's.

By jumping the #2 terminal to the large battery stud on the back of the alternator, the internal regulator only senses what the output voltage is at the larger battery stud.
The regulator will maintain 12-14 volts at the large stud, while down stream you may only have 9-11 volts on the electrical system.

For the best system performance the #2 terminal wire should connect down stream at a main junction in the electrical system where a voltage drop is more likely. This way the regulator will maintain 12-14 volts at the main junction where it is needed.

If you look at your wiring diagram, the system main junction is at the old voltage regulator BAT terminal.
Ernie

59 Biscayne 2dr
65 Elcamino
97 Z71,K1500,5.7
06 GMC Canyon


 
59impalajp 
Senior Member
Posts: 237
59impalajp
Loc: Chile, South America
Reg: 04-13-05
Re: Generator to alternator wiring modification ..help
06-10-06 05:36 AM - Post#948556    
    In response to 59 EWW

Quote:

Hi JP

Most people do not take advantage of the voltage sensing aspect of the internal regulator on the 3 wire alternator's.

By jumping the #2 terminal to the large battery stud on the back of the alternator, the internal regulator only senses what the output voltage is at the larger battery stud.
The regulator will maintain 12-14 volts at the large stud, while down stream you may only have 9-11 volts on the electrical system.

For the best system performance the #2 terminal wire should connect down stream at a main junction in the electrical system where a voltage drop is more likely. This way the regulator will maintain 12-14 volts at the main junction where it is needed.

If you look at your wiring diagram, the system main junction is at the old voltage regulator BAT terminal.




Hey EWW.
My idea is to take advantage of the remote sensing wiring with the 3-wire alternator and have strong ignition (HEI), lights and electrical system.

On the other hand, MY QUESTION was:
What's happend if I use the Battery positive terminal as the main junction?.
That way you will be "sensing the system AT the battery positive terminal. or not?.

jp
59 Impala Sport Coupe


 
59impalajp 
Senior Member
Posts: 237
59impalajp
Loc: Chile, South America
Reg: 04-13-05
Re: Generator to alternator wiring modification ..help
06-10-06 06:09 AM - Post#948557    
    In response to 59 EWW

Hi.
I found the following wiring diagram on the webb showing what I mentioned in my last pot.
That is routing the alternator BAT terminal directly to the Battery positive terminal, same as the aternator sensing terminal #2.

any comments about it?.
thanks
JP

59 Impala Sport Coupe


 
59 EWW 
Very Senior Member
Posts: 1871
59 EWW
Loc: Kansas City Kansas
Reg: 08-31-03
Re: Generator to alternator wiring modification ..help
06-12-06 11:33 AM - Post#948558    
    In response to 59impalajp

There's nothing wrong with the way that diagram show's to wire the alternator, but, is it the best for system performance, I don't feel it is and neither did GM.

If you look at wiring diagram's of late 60's and early to mid 70's GM cars when the 10&12SI alternator's were used, they ran the alternators large BAT cable to a main junction point along with the #2 voltage sensing wire to that same point in the wiring harness.

If you notice most of the major circuits spyder out from the main junction point, this is where a voltage drop will most likely occur, what better place to sense the system voltage. The battery is at a ending point, not a good place to sense system voltage.

Primary reason for the battery is to start the car, primary reason for the alternator is to run everything first, and charge the battery second, once the engine is running.
Ernie

59 Biscayne 2dr
65 Elcamino
97 Z71,K1500,5.7
06 GMC Canyon


 
Chair City 
Contributor
Posts: 354

Loc: Thomasville, NC USA
Reg: 01-24-04
Re: Generator to alternator wiring modification ..help
06-12-06 02:27 PM - Post#948559    
    In response to 59 EWW

A look at the 59-60 wiring diagram above shows that a single 14 gage wire supplies the entire system (except horns).This wire branches inside the dash harness to the light switch, fuse box and ignition switch. Sensing the voltage at the Bat. terminal of existing voltage regulator will do little to raise voltage at ign. sw, lights etc. as most of the voltage drop is downstream of the regulator Bat. term.
As Ernie pointed out, the ideal point to sense voltage would be where the circuits branch off. In this case that point is in the dash wiring harness.
1960 Impala Spt. Cpe. Daily Driver


 
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