kel

Put a new alternator on and am measuring 16.57 volts across the battery terminals at 1500 engine rpm? Is this too much? I don't want to fry the electical system!

The volatge regulator was replaced recently as well. Battery voltage prior to changing the alternator was less than 12 volts.

SilverC1

Voltage with the car (and alternator) running should be more like 13.5 to a little under 14 volts. Maybe the voltage regulator is not hooked up right, or the replacement voltage regulator wasn't good?

rgs

On a fully or near fully charged battery, 13.5 to 14 is expected. On a moderately discharged battery, 16.57 on initial startup and charge is also expected. If the voltage does not drop after a few minutes of charging, then I would start looking at the regulator. The original mechanical regulators can be adjusted to fine tune the charging system.

kel

I don't think I can see how the voltage regulator could be hooked up wrong, it's just a plug in.

The shop manual states voltage can be as high as 15 volts so I'm not too far out of the ballpark.

I'll try adjusting the voltage regulator and see what we get.

One other thought I had was maybe I have the wrong alternator. The location of the connection points are about 90 degrees off from the one I took off. Also, the pulleys seem to be about 1/8" to 1/4" out of alignment due to the shaft of the alternator (the Alt sits back too far from the front of the engine). Does anyone know how long this shaft should be?

Vetterodder

Check the ground to the regulator. You can do that by connecting one end of a wire to a known good ground and the other to one of the regulator's mounting bolts. If the voltage drops to normal you've found the problem. I went through this before and learned a couple things about 40 year old plastic cars. One: 40 year old wires might still look good on the outside but they might not be so good on the inside. Two: an ungrounded regulator will wipe out the alternator and the battery (and the battery acid that boils out will do other damage).

Cmacsvette

All good points above. I do not believe you have the wrong alt. as far as the elec. out put goes. The ground issue is a good check. Also you said you had 16.57 when you checked it and the manual said 15, but are you totally sure your instrument is dead nuts on to begin with? Your talking 1.57 here............could be just a calibration error.
Also as said before, your volts on start up w/ a low batt. will be higher.
They also build a solid state reg. for these cars which is a real trick deal.
You can even install the old Delco covers on them. These regs are accurate in providing smooth voltage control, over mechanical regs.
Craig

ghostrider20

I replaced my stock VR with a $9.00 solid state unit. Looks like the stock one, and works hassle free.

As mentioned you shoud check voltage across the batt, a few minutes after start-up. A consistant charge of 16+ will boil the battery over and cause massive corrosive problems for the tray.

Mark

babbah

I have same problem, How do you adjust the mechanical voltage regulator to reduce the voltage output to the battery?

JohnZ

This procedure is shown in detail in the Chassis Service Manual in Section 6Y, Charging System.

red67

I have the 16 volt problem also. New fully charged battery, new delco alternator and new regulator. At idle my digital voltmeter showed 16.2 volts. Now how about this one, I put the old alternator back on the car(it worked fine, but looked rough) and I got 14.4 at idle. I took my new alternator back to napa and we put it on the machine to test it. It had an output of 14.5 volts. I cant figure this one out??

kel

Here is an update.

This may apply to you too red67!

Seems my Dad on a whim tried a different voltage meter and got a reading of about 14 volts. He checked the different meter against a third meter and it matched up to the third meter. Seems the first meter was off by about 2 volts or so.

plaidside

There are a few things that can have an effect on voltage at the battery being high.
The first thing I would check is the ground at the regulator as suggested.
On these old systems the regulator uses the red wire in the four wire plug to "sense" the voltage at the battery. If the voltage at the red wire is lower than the actual battery voltage then the regulator tries to bring that voltage up to around 14 volts. But when the voltage is 14 a the regulator it will be higher at the battery.
So what I do is when the engine is running first check the voltage at the battery and then at the red wire at the regulator. They should be very close in reading.