Alternator problem?

[forfamily]

I have a 68 coupe with 289.

From what I understand it is somewhat normal for the headlights to dim when idling, however the heater blower slows as well and puts out minimal air. The lights brighten and blower speeds up as RPM is increased. Is this normal?

The car is pretty much orginal so there aren't added accessories drawing the system down. The blower motor looks like it was replaced by the previous owner.

Any suggestions for upgrading to a higher output alternator without going to much away from orginal?

 

[A67StangMaster]

sounds like you have a bad ground connection from your alternator..

If that dosnt work you might need to get a higher amp alternator. would recomend a powermaster 1wire setup. easy to install less wires up front..

 

[krash kendall]

Use a multimeter to test your voltage at the battery. Should be 12.5 off and 14.4 +/- with the car running.

 

[mustangman1974]

Also check to see if your belt is tight on the alternator.

 

[rc4mike]

i have the same problem with my 65 and painless wires harness throughout. Lights dim at idle. Sometimes i have 10v at the battery and sometimes 13.5. Mine has a new alternator with new regulator. When insalling reg. i wired something wrong and smoke came from regulator. I have a feeling that the reg is working intermitantly. Now my left turn signal wont flash, but the rig t one does. This was working...now, nothing. What a pain.
mike

 

[D.Hearne]

If the left's not flashing one of the bulbs is probably burnt. Using a heavy duty flasher usually prevents the "no flash" when one's burnt.

 

[forfamily]

If the left's not flashing one of the bulbs is probably burnt. Using a heavy duty flasher usually prevents the "no flash" when one's burnt.

Yes we just had the same issue last week. The left turn signal was not flashing. My son didn't believe that it was a burnt bulb. Dad was right for a change

 

[forfamily]

Use a multimeter to test your voltage at the battery. Should be 12.5 off and 14.4 +/- with the car running.

Voltage across the battery was 12 volts, when I first checked it this morning.

We started it up, let it warm up and settle to 550 RPM. At that I am getting 13 to 13.5 volts.

After shutting it off the battery voltage was up to 12.5.


The belt is tight.

Electrical is definitely not my strongest point, what should I look at from here? Should I just go through and check/clean connections?

 

[krash kendall]

It sounds to me like your battery is a little weak and is dragging the alternator down, or the alternator is weak causing the battery to be over taxed and weakening it in the process. I'll bet the latter, meaning a new battery and alternator are in order.

Both my truck and my car have had alternators that went bad and made the battery unreliable.

If you take it into a shop (or I think autozone can help you in the States) they can load test the electric system (usually for free) and tell you for sure.

 

[67coupe351w]

Voltage and Amperage aren't the same thing.

You read 13.5 volts because that is the voltage the alternator is regulated to put out but when it is spinning slow its not putting out enough amps to meet the current requirements for your headlights and your blower motor along with other current draws (stereo, ect).

There is a good chance that installing a higher output alternator won't do anything for you depending on how the output of your current alt. and the new alt compare at idle. Having a higher maximum output doesn't nessicarly mean its output curve is shifted up through-out the RPM range. Output curves are not linear and alot of times are almost the same at idle speeds. Thus you need to adjust pully ratios.

Measure the diameter of your crank and alternator pully. You want the diameter of your alternator pully to be 3 to 3.5 times less than the diameter of the crank pully for street use, up to 1.75 times less for pure drag racing use, and the same diameter for circle track use only.

If your ratio is already up at 3-3.5 then you may want to look into a new alternator because yours may be tired.

 

[rc4mike]

i replaced my regulator and now am getting 13.5 v at the battery...so that one is solved. Lights still a little dim at idle. I'll check the left blinker bulb.

thanks

mike