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Post Info TOPIC: 10DN Alternator Upgrade
Bobs_Place


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10DN Alternator Upgrade
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The alternator output seemed low at times on the Chevelle with the A/C and head lights on. Last fall I checked voltages at alt, bat and the regulator, they were low as I suspected with the load from the lights and A/C. Voltage was good without load. So the alt was charging but could not keep up when needed. I used an alt that I assembled with part that should have given an output of about 61 amps.

So over the winter I ordered an electronic voltage regulator and a kit to upgrade the alt to 80 an amp output. The kit comes with a new stator (with more coils for higher output), higher capacity diodes, brushes and some misc. small parts.

I have a few alternators on the shelf so I used the good parts from them, the first one I grabbed the bearing was loose in the cover, the next one was good and the rotor looked better, so I polished the contact rings, cleaned up and assembled the rotor into the front cover. Next I gently pressed out the old diodes cleaned the heat sink pressed in the new diodes  making sure I used the correct polarity diodes. Then replaced the diodes in the rear cover, also  pressed a new rear bearing, and than the new stator, installed brushes, made all the connections and assembled the two halfs.



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Bob W.

Lino Lakes
Bobs_Place


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last week I replaced the alt on the car with the one that I upgraded to 80 amp and replaced the voltage regulator with the electronic regulate. I did the VR first to compare the differences before replacing the alt, I found that the voltages were basically the same with accessories turned on, no better output from the alt., however, full charge voltage was about a 1 volt higher 14.2-14.4 and I could almost always see the head light pulsate, which was reflected in the volt meter readings, that was eliminated with the electronic V reg.

I then replaced the alt, at idle (850RPM) voltages at were slightly better than before but still did not support the full load of the A/C, fan and lights. By raising the engine speed to about 1500RPM voltages were in the 14v range.

I was also concerned about the extra heat that would be created by the higher output, so I reduced the clearance between the fan and the front cover to about .020-.030 by narrowing the spacer between the fan and the front bearing. I saw about 20 to 30deg cooler on the stator with the inferred temp gun. I'm sure my temp testing was not accurate do to possible differences in ambient temps and alt output but it's still worth checking.

I am a bit skeptical that that the alt will last with the higher temp but I did want to try it as I do have a spare to use if needed.

I then disassembled the alt. that came off the car. It is an alt that I installed a different stator in from (I think) a 61 amp alt. The stator has more coils than the 37 amp stator, and everything tested good but I don't think I was getting a full 61 amp when needed.



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Bob W.

Lino Lakes
jim larson


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Interesting Bob, especially since I am trying to add AC.  On factory ac the 66 used a different alternator, I like a 61 amp.  But on the custom ac system it just calls for the standard 37 amp alternator for a manual trans car.



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Jim L

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Bobs_Place


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I don't know what the "custom ac" fan pulls, the factory or Four Seasons heater/AC fan pulls a little more than 15 amp on high as I recall. The AC clutch eats up 3 amps, then there is about 12 to 15 amp for lights. Not much left for the battery, high beams, ignition, etc. with a 37 amp alt that doesn't put out until engine RPM is up to around 1500 to 2000.



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Bob W.

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jim larson


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Bobs_Place wrote:

I don't know what the "custom ac" fan pulls, the factory or Four Seasons heater/AC fan pulls a little more than 15 amp on high as I recall. The AC clutch eats up 3 amps, then there is about 12 to 15 amp for lights. Not much left for the battery, high beams, ignition, etc. with a 37 amp alt that doesn't put out until engine RPM is up to around 1500 to 2000.

The Blower/fan for the underdash AC unit looks just like the fan for the heater, I think it might be the same , I didn't check part number stamped on housing.   The heater blower fan cable is disconnected upon installing of the underdash unit, Thinking it still works though.  By not turning the heater fan on wouldn't  the draw with the AC unit on would it be the same and with a heater fan on?



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Jim L

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Bobs_Place


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If the underdash A/C fan is the same as the factory heater fan, than when the A/C is on high than the only extra draw would be the 3 amp s from the compressor clutch. Just checked a fan from a none A/C car, it pulls 6.6 amps, less than half the factory heater/A/C fan draws.



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Bob W.

Lino Lakes
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