[Bob Lincoln]

They might be good. There is a 5V regulator on the back of the instrument panel which, if it fails, causes the gauges to be inoperative. Unless you tested the gauges that you bought with a separate power supply on a bench to demonstrate that they're bad, I'll bet they work. If you tested them in the car, check the 5V regulator. It's probably bad.

 

[faithfulfly]

I'm trusting my mechanic to install these for me. He's been working on the car for about 14 yrs now and I trust him pretty well. My old gauges burned out when the regulator went bad. I then bought a used cluster off ebay and he installed them. After a test run he's telling me they aren't any good. I may just risk buying another cluster because I love the car, but it is a driver and I can't see myself spending a ton on new gauges. They seem to run about 100 dollars a piece for the fuel and temp in the places I've looked. I'm afraid to even see what the speedometer runs.

 

[CudaPete]

I have a complete cluster from a 73 that I'd be willing to let go for $100.

 

[Bob Lincoln]

If the replacement cluster had non-functional gauges, maybe its regulator was also bad. Was it also tested?

Or there could be a fuse or fusible link blown. The odds are astronomical that all the gauges in two different clusters are bad.

 

[faithfulfly]

I have a little more info now. The gauges I bought recently will move but they don't move correctly. The speedometer bounces around from 30 to 70 mph. The fuel gauge will move up to the empty mark but not any further. The temp gauge will function normally until the thermostat opens up then it'll drop straight down to 120. The alt gauge jumps up to +40 when the accelerator is pressed. The gauges that I had on there at first stopped working. The speedometer would bounce around like a lunatic.

 

[Bob Lincoln]

Well, the speedometers of that vintage are entirely mechanical, so that problem is unrelated to the other gauges. The speedometer is probably a cable that needs lubrication.

 

[Dave Z]

Yup. The cable issue has been very well documented. See http://www.valiant.org for fixes.

The voltage regulator issue has also been very well documented and Rich Ehrenberg has a detailed set of fixes.

http://www.allpar.com/fix/vintage.html has a list of links which should have the exact article.

 

[CHRYNY]

You need to bench test the electrical gages individually to see if the gages (both your old ones and the new ones) are really all bad. Electrical gages are generally robust. It is unusual for an entire replacement set to be problematic as you suggest. It is more likely that you have issues with the ground, connections, ciruit board, wiring or instrument regulator. (Unless your replacement set looks like it has been water damaged and looks rather rusty.) The instrument cluster voltage regulator is avaialble from Rockauto online and probably from a local parts store like NAPA.

 

[CHRYNY]

If after individual bench testing, you verify that that fuel and temp and ammeter gauges are indeed bad, Arizona parts seems to have them in stock. http://www.arizonaparts.com/

Have you also confirmed independently (clamped ammeter output amperage measurement or voltage measurement on battery and/or alternator voltages output/field and thermal sensor gun for temperature) that the gages are not actually reporting other problems on your car? For example, the high current indication does not correspond to excessively high charging? The temperature is not actually falling off as indicated? Bad fuel tank sender unit?