Charging system

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Old Jul 5, 2025 | 08:27 PM
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Charging system

I have a 1969 olds cutlass with AC and 350 engine. My alternator/external regulator are no longer charging battery. I am not sure which part failed. I see battery voltage level only with car is off or running. I think I want to change to an internal regulated alternator. I am aware of the wiring changes to make but am looking for information on what alternator to buy (part number).
Old Jul 5, 2025 | 08:39 PM
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You'll receive several to many good recommendations. Firstly, a little more data would assist in diagnostics to ensure the steering committee can assist you're heading down a good path.

(1) What is the measured DC voltage at the battery w/ car OFF not running?
(2) What is the measured DC voltage at the battery w/ car ON & running at idle w/ all accessories turned OFF?
(3) What is the measured DC voltage at the battery w/ car ON & running at ~2,000 RPM w/: (a) all accessories turned OFF & (b) all accessories turned ON (accessories = AC, headlamps, radio, etc.)?
(4) Do you have a need to increase ALT amperage rating based on any additional aftermarket accessories i.e. stereo amplifiers come to mind?
(5) Is the currently installed ALT & VR OEM equipment? What amperage/model number if known?
Old Jul 5, 2025 | 09:58 PM
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Originally Posted by bluecutlassconvertable
I have a 1969 olds cutlass with AC and 350 engine. My alternator/external regulator are no longer charging battery. I am not sure which part failed.
Your local auto parts store can test the alternator.
Old Jul 5, 2025 | 10:17 PM
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Originally Posted by Fun71
Your local auto parts store can test the alternator.
And the regulator
Old Jul 6, 2025 | 06:46 AM
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When it failed, I saw the same voltage at the battery and alternator connection when the car was running, ~11.6.
The generator light did not come on.
I don't know yet if they are OEM parts.
I am presently not running any extra electronics.
Based on documentation it should be 55 amp.
I will pull both parts and get them tested later today.
If I stay with external regulator, is it better to get solid state one?
If I decide to go with internal regulator, is they a part number you recommend?
Old Jul 6, 2025 | 06:49 AM
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Eventually you'll get around to reviewing what has been posted to this thread. This topic appears often & as you can imagine has some dependency on model & year of production. I haven't changed an external to internal VR ALT for a 1969, others have. To assist, finding the correct information can be cumbersome. Most of us review many threads gaining information along the way. In the meantime, as you garner more information, here's a decent thread specific to a 1969 Cutlass you might find informative.

EDIT: Our paths crossed (in timing) as I was formulating this post response & just noticed you responded.

1969 Cutlass S 350 internal reg alternator
Old Jul 6, 2025 | 09:25 AM
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Originally Posted by bluecutlassconvertable
If I stay with external regulator, is it better to get solid state one?
I would not say it’s better, they both do the same job but in different ways.

My experience is the mechanical regulators are more durable than the solid state ones, and the mechanical ones can be repaired whereas the solid state ones cannot - at least I have not found a way yet. I repaired my original mechanical regulator back in the 90s and it’s still working well.
Old Jul 6, 2025 | 10:24 AM
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I have removed alternator and regulator. Both are Delco parts but don`t see any numbers.
The regulator has the tab bend up on the blue wire?? Don't seem correct. This is my first time looking at these parts. Not sure why its bend up. Any thoughts?
Old Jul 6, 2025 | 12:14 PM
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Alternator fails and 4 different places could not test regulator.
Old Jul 6, 2025 | 01:23 PM
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So, you know you have a failed/bad ALT. At this point is a functioning or non-functioning VR of importance? I'll hedge to suggest the VR is likely OK & the issue resides w/ the ALT. To that end, you're going to require a new/rebuilt ALT. So (I think) the pressing decision remains external or internal ALT? You're going to require one or the other, right?
Old Jul 6, 2025 | 01:41 PM
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You are correct.
Think I am going rebuilt internal from rock auto
ACDELCO 3342189 Gold; Remanufactured; 78 AMP
$48
Old Jul 7, 2025 | 08:09 PM
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Charging system

Here is an article I wrote on how to check your charging system.
Joe
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