Variation in light brightness when lights on or accesories performance.......

[richard1]

Well...sorry for the confusion of the title of this tread. i observed this morning that the brightness of my headlights is lower at idle than at throttle no matter my A/C is on or not.

Could it be just my alternator belt that is not tight enough?????it doesn't slip on the pulleys when the engine is shut down but at higher RPM it waves a bit as a bad belt and it is the same from my A/C compressor belt side.

My belts are new from the last year, alternator replaced last year also and voltage regulator in same time.

It is a 72 240z.

I know that the A/C draws a lot of power from the engine and is always on because I live in Vegas.

Engine cooling is in the middle of the gauge, timing is perfect, engine peppy in all climate fluctuation with electric gas pump at the back, points setting perfect (change every 500 miles because the best as Standard brand wear off very fast)

Coil is one year old......distributor rebuilt...distributor cap with brass contacts..... excellent as rotor....recent spark plug wires.

As you may see..... a very thigh scheduled maintenance control.

The only thing I missed......the condensor.

Could it be the problem ? I have several new ones in my toolbox but I don't replace it every time I replace the point set.......last time I replaced the condensor may be a year ago. i changed point set may be five times since without replacing the condensor,

Please, explain me what is the real function of the condensor if it is my problem. I cannot see anything else.

[Arne]

Richard, that's quite normal for the stock 240Z alternator. It doesn't have the output at idle to keep everything at full bright. Actually not that unusual for many cars of this vintage.

The only real cure for this is a higher output alternator. I think the stock output on a '72 was 45 amps. (My '71 was only 40.) I have a 60 amp 280ZX alternator on my 240Z to aleviate this issue, and also to power the H4 headlights. Pretty much a bolt-on deal except that you need a voltage regulator bypass.

[richard1]

Thank you for the info. I called my supplier and my unit is rated at 60 amps as per their specs (NAPA), I never noticed this variation before......because now I commute very early in the morning and I see the difference in lighting intensive.

During the worst of summer, cooling fan for the A/C condensor, A/C on, full blower and everything else were on but I never experienced a significant lack of energy.

What do you think I could check.....I only have the A/C at all time and nothing else. Is a battery charge would fix the problem? I have no cranking problem and the car perform flawless at every start up no matter 110 or as now around 95 F no matter I shut down the engine five times or more in the worst of the day.

I tightened the alternator belt but I don't see significant improvement.

[Arne]

Well, with the stock alternator in my car with the lights, wipers and heater fan going, everything was slow, dim, or both. Sitting at a light with the turn signal on was almost painful to look at. My car is quite fine with the ZX internally regulated alternator.

Regardless of what NAPA says, if your alternator is an externally regulated unit, I strongly doubt that the output at idle will be able to keep up. (We'll ignore the fact that I have never heard of a 60 amp externally regulated alternator for a Z.) If adding just a few revs brings things back to "normal", I can't think of anything that you could do to remedy this short of upgrading the alternator.

The reality is that what you describe is normal for a stock 240Z.

[JonnyRock]

From my experience, Arne is correct. Don't take NAPA's word on your car's specs. Especially if it's still externally regulated.

Could it be the problem ? I have several new ones in my toolbox but I don't replace it every time I replace the point set.......last time I replaced the condensor may be a year ago. i changed point set may be five times since without replacing the condensor

What could posses you to fiddle with the points that much? Have you not gotten the settings where you like them yet? Because it's my understanding that the points and condesor should be left well enough alone unless you know something is wrong. I think people replace these far too often during "tune-ups" when there was nothing wrong with what they had.

If it ain't broke, don't fix it.

[=Enigma=]

The condenser regulates the spark between the point contacts ensuring a consistent spark and helps prevent the points from burning up prematurely. The points and condenser are supposed to be replaced as a pair, and they should last for a lot more than 500 miles. Note that it's normal to see some arc build-up (for lack of a better term at the moment) under normal conditions and this can be safely filed off with a points file. If the points are getting burned up prematurely, I would suspect a faulty condenser or too small of a gap.

Edited September 19, 2009 by =Enigma=