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Old 03-14-2011, 05:17 PM
  #5  
burgessdg
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Join Date: Aug 2007
Posts: 25
Default alternator help

Not sure what you have. GM first generation Alt had a 2 wire plug as did the second generation (1972 thru 80"s?). I would not waste time with first gen it had an external regulator. Second gen had an internal regulator. I have put the second gen in dozens of pre-72 cars. I am not sure how a 1-wire works, but I would guess it is the similar to my method only internal to the alternator. My method comes from a 1976 Chiltons manual (testing section), here's what I do... Battery connection on alternator goes to Pos battery or thru ammeter if you have one and then to battery. Flat plug terminal 2 goes directly to pos battery (not thru ammeter). Flat plug terminal 1 goes to a 10 ohm (6 watt) resistor and the to pos battery. I abandon the wires from the plug unless they go where they need to. I don't care about idiot lights.

As far as charging voltage, specs are like 12.8 to 14.5 volts. If you are putting out 13.8 at idle with no accessories, when you turn accessories on, voltage might dip slightly, but should recover to 13.8. That's the regulator adjusting for load. If voltage does not recover, you have a bad regulator or alternator. Or, your alternator is too small for your loads. They made 35 amp thru 100 amp alternators. I have a 35 on my '59 'cause it's what I had and all I have is lights and wipers. I have a 60 amp on my '69 'cause it has power windows.

Good luck,
Dan
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