1971 Plymouth 'Cuda originally 383-4, now 440-6

OK, so I just got my engine running. In the process of overhauling and installing my engine, I bought a new wire harness from Year One. 440-6 electronic ignition harness. I had a Tuff brand single wire alternator that I installed. I am using a stock type voltage regulator on the firewall and just disconected the one on the back of the new alternator. Here is my problem. The harness has connections for a four post balist resistor. I got one down at autozone for a 1975 V8 truck. My alternator is putting out 16-16.5 Volts at the battery and I think it might be due to the wrong balist resistor.

Can anyone confirm this and maybe give me a part number that I can get at Autozone or O'Rielys, somewhere local.

Thanks.


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Ballast resistor would not change the charging current. When you say single wire alternator, do you mean it only has one field terminal to connect like the 1969 and earlier alternators, or that it only has the battery connection and is internally regulated?

more pictures

In the interest of full disclosure, A buddy of mine wired it up for me. He told me that 16-16.5 Volts is fine. I am not buying it.


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last one


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From that picture it looks like the black and green wires from the internal regulator on the alternator were disconnected, and wires from the new wiring harness were connected?
Make sure the battery is fully charged, it it is low, it may charge at a higher voltage for a few minutes, but 16.5 sounds too high?
I would start by disconnecting both wires from the alternator field connections and make sure the alternator is not charging. Then I think the blue wire should have +12 volts when the key is on. Connect that back up and if the alternator starts charging at 16+ volts, it might indicate the other field connection is shorting to ground. Disconnect the voltage regulator plug at the firewall voltage regulator, and ohm it out to make sure it is not shorted. If it is not shorted, connect it to the alternator field connection. With the key on the two sockets in the voltage regulator should have +12 volts (disconnected from the regulator.) Connect to the regulator and start the car and check the charging voltage.
One last check before replacing the voltage regulator is to run a separate ground wire from the engine to the regulator case in case the VR ground reference is not the same as the engine?

16+ volts will fry or damage every component that is "on". I'd not run it till we get the circuit figured out

It sounds like your alternator has the field fully energized. Do you have schematic from the alternator manufacturer? If so I can direct you on how to wire it into the factory harness
Doug

Never did like single wire alternators myself.

When you disconnected the supplied regulator did you re insulate the brush holder nearest the alternator output stud? It states in the alternator instructions this brush must be grounded. If it is still grounded the regulator on the firewall will not regulate the field voltage. With the brush grounded the alternator is in the full output mode. Let me know.
Doug

Stay away from the little tin-box add-on regulator, it's cheap and will blow up. Get the correct isolated stator alternator, (2 wire), for the vehicle and wire it per the stock wiring diagram with correct regulator. The extreme high end of the voltage range for car operation at 70Amps is 15.6V. We used to test 10A mobile radios at 16.2V but just to make sure they wouldn't blow up. Nominal charge voltage for a 6 cell lead-acid car battery is 14.4V, a normal system shouldn't get much above 15V.

Well here is your update:

I bought a new externally regulated alternator.

It works great. 14.2 Volts at the battery.


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My first Tuff Stuff alternator was junk. Returned it to Summit and second one was OK. Mike

You may not know about the fix yet, but you probably still have the factory wiring problem of the output from the alternator being routed through the firewall then the amp guage and back out through the firewall to charge the batttery.

I'd look into resolving that next.