SI67

If the housing markings (1100693 37A) on the rebuilt alternator (1100693 37A) installed well over 20 years ago on my '67 327/300 with A/C are consistent with what's inside, I've been limping along with about 2/3 of the alternator capacity I should have. Other than the lights being a little dim and dash ammeter showing a slight discharge when idling with lights and fan or fan and A/C on, I've not noticed any problem. Things seem fine as soon as I come up off idle. I haven't had battery troubles--put in 2 or three since acquiring the car in late 1984. Is there some subtle ill effect about which I should be worried? I'll upgrade if this one ever quits or if I add anything that takes significant power (like EFI....).

If I've been getting along just fine with the 37-amp alternator, why did the factory specify at least a 55-amp alternator for A/C cars? Would it have been more critical in a harsher climate? I'm in the SF Bay area, so no cold weather concerns, if that's relevant.

plaidside

I would say, "if it ain't broke don't fix it".

37A was the norm back in the day and if it had A/C there was either 55A or 61-63A units installed. I would assume it was better at idle with all the accessories on.
But if you have no issues then I would worry about it when you do have one.
Joe

stellar

When you do have a problem have the rebuilder put in a 63 amp rotor and stator and you will have the higher amp alt in the 37 amp case. All other parts in the alt are the same.

Easy Rhino

^this^

The cases are the same for the different amperage, only the internal rotor and stator differ, and you cannot tell the difference.

65air_coupe

That's what I did many, many years ago - no problems since. Actually, no problems beforehand either but happier with the higher amperage.

dplotkin

Its important because two things kill batteries, heat and failure to keep fully charged.

Too small an alternator will not top off a battery after a discharge event, like a long crank cycle if it is then driven with the electrical system load exceeding alternator output and/or a short trip. So the risk is that the battery remains partially discharged at all times and has a shortened life.

If however you have gotten by with 3 batteries since 1984 I'd say leave things alone.

Dan

SI67

Lots of good info from you folks. It's much appreciated. I'm not going to mess with it unless the 37-Amp unit fails or I add a significant load, but now I know what I'd do and why.

Easy Rhino

I would probably do the same - wait until the alternator failed or battery died (prematurely) before I did anything.