<VV> 66 Monza Electrical question

Frank DuVal corvairduval at cox.net
Sun Nov 25 09:55:50 EST 2007

The charging system on a late model Corvair is simple compared to the 
new cars with computer controlled alternators. The stock system has two 
parts, the alternator and the voltage regulator. To test easily you need 
a digital voltmeter (DVM) or a volt-ohm-meter with a scale that you can 
read the difference between 12.6 volts and 13.5 volts. Even a $5 Harbor 
Freight  DVM will work here.

To "calibrate" the meter, measure the battery voltage (engine off, key 
off) of another car that is charging fine. This reading should be 12.6 
volts, but does vary a few tenths. Now start the car and measure the 
battery voltage while the engine is running. This charging voltage can 
be anywhere between 13.5 and 15 volts depending on state of charge of 
the battery and other factors not important here. Now you know the two 
correct readings on your voltmeter, even if they are not 12.6 and 13.5+.

Now measure the same two readings on the Corvair in question. If the 
engine off reading is less than the "control" car, the battery needs 
charging. If the car does start, and the engine running reading is less 
than 13.5 volts (as shown on the "control" car), take a jumper wire and 
touch the F terminal of the alternator to the + terminal of the battery. 
The voltmeter should now read 13.5 + volts if the alternator is good and 
the voltage regulator is bad. If the reading is still low, the 
alternator is bad.

As a previous poster said, a lot of FLAPS will do this test for free. 
That is even cheaper than a $5 meter. And faster if mail order is involved.

Frank DuVal

Shari Hebrink wrote:

>My daughter's 66 Monza Coupe (110 HP) has an electrical problem.  She has
>had this car about three months.  I replaced the battery last month after it
>tested completely dead at the FLAPS.  This weekend, the new battery is not
>charging or else not holding a charge.  It barely turns the engine over.
>Any suggestions where I should start looking for the problem?  I presume the
>alternator (or is it a generator?) would be the first thing to check.  Next,
>I suppose would be the voltage regulator.  If these both check out okay,
>does it suggest that there is a short somewhere that is draining the battery
>when the ignition is off?
>Any thoughts or suggestions would be greatly appreciated!  Electrical
>problems always leave me confused!
>Many thanks,

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