1965/396 Charging Issues

[Richard S.]

My 65/396 alternator does not seem to charge the battery until the car hits around 3000 RPM. In talking to a local mechanic (Hot Rod Guy) he has mentioned that if you were to change the 3 5/8 inch pulley to a smaller size it might correct the issue. Has anybody tried this and with what results?

So looking at alternator today i found the part number was 1 100548 61v. There was numbers below it that i could not make out. Does anybody know what this is alternator is off of as the correct number in my book is 1 100696. I am not a real technical guy so this all the information i currently have.

All help will be appreciated.

[Joe L.]

Re: 1965/396 Charging Issues

My 65/396 alternator does not seem to charge the battery until the car hits around 3000 RPM. In talking to a local mechanic (Hot Rod Guy) he has mentioned that if you were to change the 3 5/8 inch pulley to a smaller size it might correct the issue. Has anybody tried this and with what results?

So looking at alternator today i found the part number was 1 100548 61v. There was numbers below it that i could not make out. Does anybody know what this is alternator is off of as the correct number in my book is 1 100696. I am not a real technical guy so this all the information i currently have.

All help will be appreciated.

Richard------


Your alternator, or, at least the drive end frame with the numbers, originated on a 1974 Chevrolet truck. However, the numbers are pretty meaningless as this alternator has almost certainly been through a commercial rebuilder's operation. So, the original part number is meaningless as the alternator was built up from reconditioned and new components. The GM #1100548 was an internal regulator type alternator. However, I believe the drive end frame may be sometimes used by rebuilders to build up external regulator-type alternators such as your application requires.

Changing the pulley is a band-aid approach to solving this problem. I don't recommend it. You likely have a problem with either the alternator or the voltage regulator.

[Terry D.]

Re: 1965/396 Charging Issues

Agree with Joe, changing the pulley is not the solution. Using a volt meter on the battery what does it read at an idle? What does it read at 3000rpm? Most any NAPA or auto parts store can check an alternator for you. And since it is not original anyway, it will be easy to replace!

Terry

[Carl N.]

Re: 1965/396 Charging Issues

If you still have the TI ignition system, you need 42 amps, which is what the "696" alternator is rated at. Anything less or more could compromise your TI system. Pulley idea is not even a good bandaid. Go to one of the chain parts store and invest in a rebuilt 42 amps alternator. Have them check it on test machine and make sure it is close to 42 amp. A "696" date correct may not fix your issues. Imo I would not spend big $$$$'s on 696 unless you are flight judging. One item often overlooked that could cause what you have is open circuit in headlight switch. Check out alternator before chasing other components.

[Gene M.]

Re: 1965/396 Charging Issues

Another option is you can buy an alternator that has 100 amp output. Also available is the guts to do the same. If numbers is a requirement find a good case or used alternator at swap meets and rebuild it same as mentioned. To be honest the 42 amp model will not be much different. As was said the smaller pulley diameter is more realistic at providing better out put at lower RPM's.

If car is a driver and you don't care about flight judging easy up grade to internal regulator unit would open up options of more output in a similar size unit. D&B Electrical on line has real good quality all new units for under 100 bucks.

[Richard S.]

Re: 1965/396 Charging Issues

Gene,
I have only owned the car for 4 months and it was sold and bought as a true survivor. That being said i do not for see it being flight judged in the near future but i want to keep it original as i replace items. Would the 100 amp internal regulator alternator output be better at lower RPM as the car will be driven locally in the upcoming months? Do you think that it could cause any issues with TI?

I really appreciate your input on this issue.

Rick

[Richard S.]

Re: 1965/396 Charging Issues

Joe
If i change the alternator should i also change out the regulator at the same time?

[Leif A.]

Re: 1965/396 Charging Issues

I may be completely off base here, but I would be a bit concerned pushing 100 amps thru 52 year old, non fused wiring...just sayin'

[Joe L.]

Re: 1965/396 Charging Issues

Joe
If i change the alternator should i also change out the regulator at the same time?

Rick------


Given the problems that a lot of folks with external type regulators seem to be having these days with replacement regulators, I think I'd be more tempted to have the original tested and rebuilt by an experienced shop. Of course, if I could find an old NOS regulator in a pull string box I'd definitely go that way.

You can also have an external regulator rebuilt with solid state "guts". That may be the best way to go. 1969+ internal regulator alternators with solid state regulators are very reliable.