Electrical problems. Dimming?

[docerz]

Does anyone know or can tell me what to do. I have a 70 rr with a new alternator (stock) yet whenever i an driving at night and am at idle the lights dim very much so. Also when i am not at high rpms my stereo will cut out as if i have no power especially when i hit either turn signal. I dont have a short with the signals and am not popping fuses. Just wondering if anyone had problems with these type of alternators. I replaced it thinking it was the alternator but in fact my old unit was fine also. I do have a 6AL box and a new kenwood cd player but nothing fancy electrical wise. I have thought about a capacitor if no one has any other suggestions. Thanks

[wilks3]

Check all your grounds first. Battery to engine, engine to body. Check the plug ins at the firewall. Have the battery load tested. Have the alt and voltage regulator tested, just because its new doesn't mean its ok. Do you still have the factory amp gauge? Check the connections at the gauge, they get loose, won't let enough current pass through. To up grade your electrical system go to www.madelectrical.com. Go to tech section, look for amp gauge replacement. Volt gauge much better anyway. INMO
Get a electrical schematic for your car. Really helps to troubleshoot and trace wires.
Check the fusebox itself, make sure all fuse holders and clips are ok and not corroded or burnt.
Good Luck!

[Dukes2fast]

Belts tight?

[ehostler]

The factory alts had a hard time keeping up, when the car was new. The 6AL take some juice and isn't happy about the voltage dipping. The Kenwood is shutting down, as the voltage is dipping below it's minimums.

As you have already modified away from stock, I would recommend a new ND alt. Read the article that is in the Performance Talk Archives. Lots of good info there.

[Tarrbabe]

First step is to put a ground strap from the chassis to the engine block.

[65TerrorCuda]

When you say from the chassis, do you mean the k-frame or somewhere else? I've got the same elec. probs.

[wilks3]

Put a ground strap from back of engine to the firewall. Also ground from engine to frame (k member). This grounds everything together. These old cars had chassis ground for everything, so if the chassis wasn't grounded good everything acted stupid or not at all. I ran seperate grounds from turn signals and taillights because sometimes they worked and sometimes they didn't. Now they do.

[cudabob496]

Also use some heavy duty ground wire. I think I use 1 or 2 gauge, about as thick as my little finger. Alternators from autoparts stores, even though they say they are for your car, are many times junk. One I had couldn't keep up either. On my 496 I also keep the idle at around 1000 rpm, since I have underdrive pulleys.

[LA360Dart]

Just a thought the MSD and Kenwood need more power, I would find out the power needs of the MSD and radio. These need to be accounted for in your power needs. Is there anything else like electric fans. Then add this to your regular demand and you should be good, as you draw more amps your voltage must fall. Later

[451Mopar]

Welcome to 1960's technology! This is a pretty common problem.
I believe the stock alternators only put out about 40 AMPS maximum at engine RPMS around 2,000+?
At idle the alternator may only be putting out 20 Amps?
The problem is not just getting an alternator that puts out more maximum current, but one that puts out more current at idle speed. Most of the newer "Denso" 90+ Amp type alternators are spun at a higher speed (smaller alternator pulley) so they put out good power at idle, and they are built with good bearings and smaller diameter windings to handle 14,000 RPM at the alternator.

[pishta]

Another option is to run all the big amp draw parts off a dedicated buss straight off the battery. MSD, stereo, especially headlights. Run them all off relays. The old harness has huge amp/voltage loss through the old crusty wire and junctions. And ground straps should not be guage wire, but uninsulated braided straps as electricity runs on the surface of the wire, not the core and believe it or not (believe it) the flow is negative to positive so the entire chassis is where it all starts. Strap head(s) to chassis, block to chassis and even K to chassis, its all good.