'66 Charger gauge problems

[JARNKM]

I have a '66 Charger that runs and a '67 Charger for a parts vehicle. Both with matching numbers. They were a Mother's Day present in '08. We owned and operated a foreign car repair shop for 45+ years. I am '71, retired and disabled.  My problem is that the Gas & Oil gauges peg, when the ignition is turned on. When it is turned off, the gauges stay pegged for a few minutes before going back to the 'park' position. I would appreciate any information on trouble shooting this gauge problem and hopefully repairing it. The '67 has a gauge panel, as well( don't know if they are good or not, though). The '66 has a modified 383 that has about 3,000 miles on it and was never raced.    JARNKM

[Pete in NH]

Hi and welcome to the group.

My money would be on a bad instrument voltage regulator. You didn't mention what the temperature gauge is doing but, I would bet it is either disconnected or it has burnt out. These regulators commonly fail when their contact points weld up and put 12 volts on the gauges. The gauges peg and soon burn out. The regulators job is to power the gauges with 5 volts from the 12 volt electrical system.

The instrument voltage regulator is a small metal can device that plugs into the printed circuit board on the instrument cluster. Some Chrysler products of the mid to late 60's had them built into the fuel gauge. I'm not sure about the 66-67 Chargers perhaps another  1st generation Charger owner can chime in here.

If yours is a plug in type you can get an electronic replacement from RT Engineering or you can still get the original electromechanical type. You can also build a simple electronic regulator circuit . Do an internet search on Mopar instrument voltage regulator and you'll find the circuit and information.

[A383Wing]

the gauge regulator is built inside the fuel gauge. It's not serviceable like most others. You must remove the cluster, then the fuel gauge and perform surgery on gauge to remove the bad limiter. Then you can wire in and external style that is electronic instead of thermal.

If you are electrically challenged with these cars, www.thegaugedoc.com can help you out

in the mean time, I would suggest you unplug the black feed wire to the fuel gauge to prevent further damage to the other gauges

Bryan

[gibber]

The most likely culprit as Bryan said is the internal voltage limiter inside your fuel gauge. It has points that most likely have stuck together, sending much more than the 5V it is designed to send to your temp and oil pressure gauges. The insulation has more than likely burned off of the nichrome wire inside the temp and oil press gauges, leaving bare wire that creates a ground. Once you turn the ignition to ON, the gauge reacts to 0 ohms (grounded) and the bi metal strip inside the gauge and attached to the pointer bends to full scale HIGH or HOT. If the gauge is allowed to operate like that for very long, that bi-metal strip becomes unusable and the gauge is unrebuildable.

Luckily I have many, many spare EL gauges for 66/67 Charger if you have to go that route. Glad to help if you decide to have this looked at...

Mark
www.thegaugedoc.com