I'm at a loss and grabbing at straws...

What he is saying is that at warm idle, it reads 12.6.

 

Yeah, that's no bueno. That wasn't apparent from the pictures.

 

12.69.

Basically running off the battery.

 

The reason GM went to the internally regulated alternators like the 10 and 12SI is that they put out triple the amperage at idle. I'm guessing you want original? Those alternators have limitations.

 

Probably around 1,100 ish or so.

 

I have the voltage regulator that came with the car, which I know works. That may be my next move as I just had that and the alternator in question tested.

Both tested fine.

 

A 12 volt battery needs 13.8 volts minimum to charge. Like I said, that is typical of an externally regulated alternator, low amps at idle.

https://deepcyclebatterystore.com/how-to-maintain-batteries/

 

Cleaned up the firewall mounting area and the mounting areas on the original voltage regulator. Viola!

Subsequent test ride felt good and seemed devoid of breaking up at WOT.

I still need to tweak some more and put a timing light on it but at least the charging issue is resolved.

Whoda thought a 51 year old part would fix this?

 

I should also note that my factory tach is off by about 250-300 RPM (low) according to my new multimeter.

I guess it might be time to have Scott Moody rebuild it and also get myself an accurate one.

 

It pulled hard during the test run, so I'll take it at this point.

I'll know more once I get the timing light on it and do a couple other small things.

I think I'm almost out of the woods.

 

Understatement of the year.