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My Nova still has the stock replacement alternator with the external voltage regulator. The problem I have is that at idle in gear it just doesn’t put out enough juice. I have an electric fan, electric fuel pump, and when I also have all my lights on and the heater/fan goin I can actually hear my fuel pump slow down and of course the lights dim. Will a one wire alternator work any better? What about a smaller pulley for the alternator? I might even use an electric water pump in the future so I really should address this issue. Thanks, Scott!
 

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A higher amp alternator should do the trick. One wire or stock setup alternator is not that much different, as far as amps are concerned. You will have to increase the wiring size to the battery.

I just installed a 100amp one-wire setup (March Perf. serpentine system). I have a dual electric fan, upgraded headlights (relay system), A/C, and a good stereo with amp and a sub. I wanted a 140 amp alternator but March Perf. does not have this option. I am still installing stuff so I do not know if 100 amps are going to be enough. I hope so...

If you are interested, I have a chrome 140amp one-wire alternator (regular belt, with less than 500 miles) that I can sell. It works & looks great! Email me if you want it.

Theo.
 

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I recently ran into the same issue. A 100 amp alternator cured my issue. I also have dual electric fans. Had an electric fuel pump. I recently switched back to a mechanical.
 

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I have some information that my friend found for his 72 nova he removed the external voltage regulator and put in a one wire alrernator. The web site where he found it tells you everything to do and give the part number for the alternator that you will need. the web site is: www.novaresource.org
 

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Wow, thanks guy's that is perfect! I am going to do the 105amp conversion. Theo if your alternator was 105 amp or so I might take you up on that, I dont think I quiet need 140 amps. I guess I could always stick an amp gauge on it and see how many I need:)
 

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Here is a link another member posted some time ago, it has lots of good info on the SI and CS series of alternators.

http://207.158.221.52/gw/alt/Alternator_Theory.html

I upgraded to an SI-12 94 amp alternator (simple bolt in swap), instead of upgrading the charging wire, I ran another one beside it to handle the extra amperage, so far the alternator has kept up with my electric load, which also includes electric fan (taurus fan) 120 watt stereo and electric fuel pump.
I always stress to get the smallest pulley that will work on the alternator to keep idle and low RPM charging voltage as high as possible.
 

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Sorry, but, I need to hijack this post..
I am still fighting the problem with the alternator I put in my car. It is a 94 amp 12SI series. My voltmeter reads 13.5 + volts if the engine RPM is over 900 or so. If it falls below that to idle around 650 in gear it only shows 10.5 or less, adn drains the heck out of the battery. Not good for a cruise night when you idle around for a couple of hours in traffic.

Any ideas?? My calculations show that the alternator is spinnign at about 2100 RPM at a 750 RPM idle which should be plenty.
 

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Hey Chief, you have a problem for sure, was your battery tested, because to draw the charging voltage down into the 10volt range sounds like a cell problem within the battery or the voltage regulator within the alternator. My SI-12 94 amp alt. can maintain over 14.3 volts at idle. Loose or poor connections in the charging and battery circuits can also cause the problem you describe. Undersized or not enough grounding can also cause problems.
Also where are you maesuring the voltage? Do you have remote voltage sencing hooked up on your charging circuit?
 

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Remote sensing is hooked up throudh the original harness. I have tried a temporary jumper to the firewall terminal without changing anything. I have ground straps from each cylinder head to the firewall and a strap from the frame to the pass. side front fender. Wherelse do you recommend having one. The battery is grounded to the engine block. I have also paralleled the charging wire to the firewall/pos. terminal.

I have thought about grounding the pigtail from the battery cable to the front fender and also temporarily wiring the sense wire to my voltmeter in the car.

What do you think..??

Mike
 

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You can try that extra grounding, then do a voltage check. On my system I measure voltage at a terminal on my rad support, this is also where all my large loads are taken from, as well my big charging wire also goes there.
But the amount of voltage drop you describe still sounds like either a defective votage regulator or bad cell within the battery. Has the battery been load tested, has the alternator been tested out of the vehicle?
 

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Neither test has been done. the shop that rebuilt the alternator said to come over adn they will test things out, but, the weather has not been with me. If it was sunny, I was cruising to a show, if it was naasty , the car stayed inside. Tomorrow is suppose to be fair and overcast, I might get it down to them for a load test. the battery was new at the start of this season, and has not given me any trouble except when prolonged idleing at the Dream Cruise discharged it and it would not restart after a fuel stop.

I will keep you posted.

Mike
 

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Took the car to the alternator shop yesterday. A young guy (read that "snot nosed punk") hooked up his Sun test set to the battery and clamped around the alternator charging wire, had mne start the car. Tester read 12.8 volts adn only about 4-5 charging amps. His solution, "crank up the idle"..!! Going to call his boss today and talk to him. I screwed the idle up to 1100 from around 650-700 before the voltage started climbing to 14.2 at about 40 amps charging current. Something definately wrong. I have removed the alternator and going to have them bench test it this afternoon.

I will keep you guys posted.

Mike
 

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Hey Chief,
Maybe that kid needed the clamp on amp probe clamped around his neck!!! LOL!

According to this site, the 94 amp SI-12 ramps up the charging current really fast, I know I run a small alternator pulley just to keep my alternator revs as high as possible, I idle at 900 RPM and can maintain over 14.3 volts on my 94 amp SI-12 alt.

http://207.158.221.52/gw/alt/Alternator_Theory.html#Section_2
 

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PROBLEM SOLVED>>>
Took the alternator back to the shop, they put it on th etester adn it put out 160 amps. They changed out the stator for a smaller (current capable) one, and now it puts out 90 amp at speed and holds 14.4V at 650 engine RPM. So I guess it true what they say, "Bigger is not always better".

Thanks for the help guys,

See you in Tennessee...

Mike
 
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