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I just bought a 68 SS with a 69 396/375 motor in it. As you rev up the engine the lights get brighter but the battery never seems to go dead so why are the lights dimming? I done a search on the board and they talk about a 1 wire alternator. Mine has one plug into it with another red wire to the batter lug. There is a ground lug on the alt but there is no wire attached to it. Is that the problem? BTW the alternator looks new and like I said it has no problem keeping the battery charged. Maybe it is one of those that do not kick in until 2000 rpm?

Thanks!

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1968 Chevelle SS396
 

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Even in brand new cars, I have a 2000, the lights will get brighter if you gun the engine. The alternators in cars are usually strong enough to make sure that the battery is being charged but it doesn't always dump out enough amps to make everything run at its peak. You can also see this sometimes if you have a thumping system, with the bass hits you can see your headlights dim (and I only have a 200 watt amp!).
 

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You need Mr. Amp, or any other beefed up aftermarket alternator. Check the pages of Summit and Chevy High Performance for the Mr. Amp and other high amp alt. ads. They're relativly expensive for alternators, but they're the best you can get.

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'70 Malibu
Engine Less (BB Bound!)
M-20 (2.56 1st)
10-Bolt 2.73 Open
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'72 Nova
355 L-31 Vortec
TH-350
10-Bolt 2.73 Open w/ Rally Suspension
 

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Just dealt with the same problem,the ground wire to the fender from the negative cable off the battery was bad, I cut it out and replaced it,also the external voltage regulator I replaced with a Wells electronic version from AUTO ZONE part # vr-715, took care of the problem no dimming at idle or increase of lighting during excelleration even with the stereo , head lights , a/c ...etc on.good luck , Manuel
 

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Ditto on the regulator suggestion. I too like the Wells unit. Inexpensive and fairly reliable. Two things on the Wells solid state regulator. 1, You must disconnect the battery when installing it. 2, The Wells case must be grounded. Use either a ground strap or remove one of the rubber well nuts that are in the core support. Replace it with a bolt and nut through one of the regulator mounting holes.
 
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