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HELP: New Alternator Lays Down 17+Amps

3K views 35 replies 10 participants last post by  mrblanche 
#1 ·
Hello, this is unusual for me because i rarely ever deal with the electrical system. to make a long story short, my old alternator on my 75' elky was on its last limb so my dad gave me an fairly new AC Delco alternator they had on a mild built early 70's GMC pickup (gotta love that man). Put it on, and it fired up fairly easy. At idle, it constantly climbs from 12amps to 14-15amps but with any peddle movement whatsoever, it goes on up. Had it autozone tested and it has been up to as far as 18Amps but usually at 16.5amps of normal driving. I dont feel comfortable with this. Help???
 
#5 ·
would the plugs on the back of the alt. labeled 1 & 2 have anything to do with it? i may have them on backwards. i switched them to see and it stayed at 12volts the whole time. both at idle and under stress. so i switched it back in fear of it not charging my battery. what do you think? also, might there be something i did wrong? it looked to be a pretty straight forward swap. the alternator was also pretty new. i also know it is possible that it could have came out of the box bad but im hoping not.
 
#10 ·
..here ya go...:beer:

http://www.elcaminocentral.com/attachment.php?attachmentid=3197&stc=1&d=1345344870

...The "Ind Light" wire might be brown (pos. 1) and the "Battery/hornrelay" wire is red (pos.2)..The folling daigram is for a 4th gen. Elky....

http://www.elcaminocentral.com/attachment.php?attachmentid=3196&stc=1&d=1345344701

..hope this helps ya...:beer:
:beer:
THANKS!!!! i understand the first picture very well but extremely lost in the second. i never understood the ink blot looking diagrams. reminds me of a building evacuation plan.
 
#12 ·
im not sure of the exact year gmc the alternator came out of but i know early 70's. i got the alt. wires out the truck and spiced them in. so maybe it did have an external thing. what am i looking for to tell if it does or did?
 
#16 ·
That is an early 70s alternator-----not what you want to use on a 75.

Pretty sure both of my 73 Chevelles are internal regulated alternators.
I'll double check in the morning.
 
#22 ·
yea, my firebird had a side plug alt. i know what that bad boy looks like. i have a v-belt if it helps anyone.
 
#19 ·
Hey Gilby, only one of your pictures comes up. I cannot view the picture of the regulator (the bottom 2 pictures). is it just my computer?? and my 75 had a rear plug alt. idk if its the original but it was on the elky when i got it. i will post pics of it tomorrow to show.
 
#20 ·
my original elky alt's rear prongs are horizontal while the new one, just like pictured in Gilby's post, has vertical prongs. thats why i had to splice the wires with it.
 
#25 ·
CORRECTION!!!!! i ran out and checked, my old alt has the plug on the top side, not the back. my new alt has back plugs. would it be that hard to use a regulator? if i HAVE to buy an internal alt then i guess I will have to but if i could also get the external regulator for the new alt for free??
 
#31 ·
So it appears you see the light now. YES, get the internal correct alternator and be done with it. FREE isn't FREE if you end up burning up a wiring harness and/or your whole Elky. With that high of voltage, even if it didn't yet turn to a fire, it would still blow light bulbs, headlights, gauge sending units, stereo system including amps etc. It's just not worth it.
 
#32 ·
You have an external regulated alternator where it was wired for an internal regulated one. The sensing wire on #2 (right plug) is full fielding the alternator(telling it to charge wide open). Be careful as it will blow bulbs and radios if you bring the rpm up too high.
 
#36 ·
I have a one-wire alternator on my T. But!!!

1. It doesn't start charging until the first time the engine is run up to 2500 rpm. Forget to do that, and you can have a nasty surprise if you're just letting it idle for some reason (tuning, for example).

2. The voltage varies more than on a regular alternator. I see 14.5 running down the road, usually, but it often drops to 12.5 when I'm on the brakes, the headlights are on, and the electric fan is on.

3. You should have a VERY good reference ground to the case of the alternator. Failing that, you may discover what I said in the post above about 100+ volts when it can't read the voltage due to a dirty ground.
 
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