Alternator problems at idle on L78 Camaro

[Mr70]

If your belt tension is tight,are all your connections clean from corrosion too?..That would put a strain on the whole system.
Mine did the same thing,until John P. rebuilt my Alternator.
I don't know if he beefed up the internals from stock,but it keeps the dash lights bright under 700RPM.

[L78steve]

Did you check battery condition?It's the batterys job to fill in when the alt.can not.It may have the capacity to start the car but not have full voltage.If a battery is not fully charged before it's put into service it will never be 100%.

[Hotrodpaul]

It would be interesting to put a voltmeter on the battery terminals while the system is under load and have a willing participant slowly increase the engine speed from idle. If the Alternator is charging, you should see around 13 volts, if not, it will be less than 12 volts. Might be a good test for the Alternator.

Paul

[Kim_Howie]

Check your grounds in the dash area

[Jeff H]

It looks to be a new battery but rather weak(555 CCA) so I topped it off on the charger for 16 hours and the lights are definitely brighter at idle now. Rev it a little and they get a little brighter but not a lot. It's reading 13.8-14 volts at idle with no lights on and drops to 13.6-13.-8 with the lights on. Then it will jump up to almost 15 volts when you rev it a little. So I don't think the alternator is a problem. I will want to get a correct 837 alternator eventually but this one should work for now. It needs a stronger battery IMO.

[70-SS/RS-L78]

Jeff what RPM does your car at?

[Jeff H]

The car has an HEI distributor in it and I'm sure the tach is reading too high. At around 60 mph it's reading around 3500 rpm's and that's with 3.55 gears and 245/60/15 tires. At idle it reads around 1100-1200 rpm's and I think it's really closer to 7-800. But things look better with the battery fully charged at this point.