I was out driving today (a minor success in itself), and I noticed that the ammeter rises with engine rpm. Additionally, the headlights get somewhat brighter and the period of directional blinking varies, which leads me to believe that the amps are indeed increasing (as opposed to a gauge issue). Should I suspect the alternator or does the voltage regulator control the amperage as well? Is this even a problem?

Thanks.

Normal on my '71. They came with weak alternators.

If your battery is fully charged and the needle deflects more than 1/4 past the middle then you might want to test your regulator. The regulator tells the alt when to make juice which shows up on the guage. Normal voltage to the battery when running will be between 13.6 and 14.2 volts. Just use a voltmeter to test this at the battery. If different, get a Haynes manual and test the reg and alt.

I normally get about a needles width deflection past center and sometimes no deflection when running regardless of electrical load. If your battery gets drained by leaving the lights on or if you have a short then the first few minutes you'll see major deflection eventually returning to the middle.

Hope this helps,

Jim

I noticed this as well on a z I am looking to buy, we were testing the head lights and one was very dim almost out. My dad turned on the car to see if it would make a difference and it did and when he revved the engine it seemed almost like the lights were a second odometer.

I noticed this as well on a z I am looking to buy, we were testing the head lights and one was very dim almost out. My dad turned on the car to see if it would make a difference and it did and when he revved the engine it seemed almost like the lights were a second odometer.

One headlight being dim is usually traceable to the fuse box. Each light gets it's own fuse. Try rotating the fuse in it's cradle to get a better connection. At least this will tell you where the prob is. There are a few threads here RE refreshing fuse boxes. It might also be a wiring issue.

You can watch the lights brighten or dim relating to engine rpm. This is normal in the early Z's.

Yes, but...

The 240Z charging system is not all that great, that's true. And my yellow car was the guinea pig for the 280ZX adapter plug and therefore has a more modern system and can not be compared to stock 240Zs.

But my red car is still totally stock, original alternator and regulator. And its ammeter does NOT continue to rise with RPM. It works the way it should - it hovers barely to the positive side of zero regardless of RPM. If you turn on an additional electrical draw, it blips to the plus side briefly and then stabilizes again near zero.

And that's pretty much what it should do, if everything is in good condition.

As for the problem described here, I'd guess it to have a lazy (slow reacting) regulator, a weak battery, or a combination of the two.

As for the problem described here, I'd guess it to have a lazy (slow reacting) regulator, a weak battery, or a combination of the two.

The battery is new. So, I don't think that is the problem.

The ammeter goes from 1/2 to 3/4 depending on the rpm. To test this should I just measure the amps and volts at the battery and at the alternator?

The brightening lights and slow-to-fast blinkers are annoying, but tolerable. Can this affect spark too? It seems like the coil would put out a hotter spark with more amps, at least. (and I have to think an MSD system- which I don't have- would barf all over itself.)

Will a new regulator fix the problem, or is it something that I should just get used to?

Thanks.

What you describe is an impending failure.

The regulator is losing the plot.

If not repaired, this condition may lead to overcharging of the battery, resulting in loss of electrolyte and possible, remote but, explosion of the battery.

Burning out of globes, overloaded fuses and general global warming are also possible:ermm:

Get the electrics checked by a competant Auto Electric Shop if you are not confident in this area.

The alternator output will ramp up when revs. increase but it is the duty of the regulator to, you know, regulate

If you are not into originality, might be a good time to adopt an internally regulated alternator and dispose of the old click clack relay type regulator.

I agree with Nissanman. If your battery is good, then your regulator is not. Either replace the regulator, or upgrade the charging system to a newer, internally regulated alternator.

The alternator output will ramp up when revs. increase but it is the duty of the regulator to, you know, regulate

Who would have guessed: regulator regulates? I thought maybe my electrical system alternates between working and not working. Seriously though, thanks for confirming my suspicions. It helps to have someone say what you knew was true, but didn't want to believe.

I'm not too scared of the wiring. I'll probably go with the ZX alternator, or a similar adaptation. This parallel thread has a discussion: http://www.classiczcars.com/forums/showthread.php?t=27677

Just doing a quick google search these came up too:

http://www.nk.ca/~zcar/pages/articlepages/alternator.html

http://www.zcarcreations.com/howto/voltreg.htm

this is what Arne was talking about.

http://1971.240z.home.comcast.net/extras/alt-adapt.html

It's easy to do (about 15 minutes) and the only wiring needed is unbolting the power wires from the alternator, unplugging the "t" plug, installing the ZX alt. and reconnecting all of 2 wires and 1 "T" plug. Then disconnect the Voltage regulator, remove it from the car, Install my ZXP (adaptor plug that is the brainchild of Arne) into the plug that the VR was plugged into and your done.

All the order info is on there, so write me at wolfin32z@yahoo.com if you're interested in upgrading.

Dave.

PS. Thanks again Arne. Ya know I can't say that enough.