Surveillance Functions Part One (Post # 120)

The 6 Veglia gauges as they looked in 1969 when I bought
The Alfatross.

"Surveillance", along with battery charging, signalling, engine starting, service, and lighting, is one of the 6 basic functions of The Alfatross' electrical system. It is a very simple system comprising the gauges and their sending units as well as a few warning lights. Far from being mere decorations, they keep watch over the condition of the engine, battery, and fuel supply. 

If The Alfatross were going to be just a trailer queen shuttling between Concours d'Elegance it wouldn't matter if the gauges didn't actually provide any useful information. All they would have to do is look good. But that was never part of the restoration plan. Every part of The Alfatross has to work.

When I sent The Alfatross' 6 Veglia gauges to North Hollywood Speedometer for restoration in 2003 I really had no idea what to expect. They had them a while, charged me $1,356.28, and sent them back. I thought they looked great and was pleased! They didn't actually get installed and tested until winter 2015, at which point I discovered to my surprise that the oil and water temperature gauges didn't work. Then the mechanical tach cable broke. 

This made me realize there is a lot more to "restoring" gauges than just making the bezels and faces look good. I began to get suspicious. How can gauge restorers make sure the gauges work with the senders in your engine unless you send them the senders, too? No one ever mentioned that although it should have been apparent to me from the beginning. 

The water temperature gauge on Dan
Allen's workbench.  The sender is
immersed in a pan of water heated to 170
degrees.  The gauge is calibrated in Celsius.
Dan Allen.

The large tachometer and speedometer are centrally located above the wheel and surrounded by the smaller oil pressure, oil temperature, water temperature, and fuel level gauges. The mechanical oil pressure gauge worked fine, as did the fuel gauge after fiddling with the sender, but the two temperature gauges were completely dead--no needle movement at all. Apparently, to the guys at North Hollywood the word  "restoration" does not include making sure it works. So what was wrong?  Was it the gauges themselves or the senders or the wiring that connects them?  How do you trouble shoot them?  I knew needle movement on the gauge is based on changing resistance in the circuit between the sender and the gauge and that it can be adjusted, but even if the needle moves, how do you know the reading is accurate?  

I went on line to find out more about gauge problems and how to cure them. Not surprisingly there is a ton of information available on the subject in general, but not so much relating directly to Veglia gauges manufactured in 1954. The article below was helpful, but describes the calibration procedure for instruments having electromagnets that can be adjusted without opening their cases. To access the adjustment screws in The Alfatross' temperature gauges you have to open their cases--something I didn't want to do.  

This article in particular was helpful and deals specifically with gauges on a 1960 Giulietta.
Giuliettaletta Spring 2001.

The next challenge?

After flailing around for several days I contacted Dan Allen to get his advice and ended up sending him the water temperature gauge for an autopsy. Turns out the gauge could be repaired and, once mated to a compatible sender he had in his stash, could be adjusted to read accurately all the way to boiling. I re-installed the water temperature  just in time for the Santa Fe Concorso and it worked perfectly, but the oil temperature gauge was still moribund--and I was about to discover a much bigger problem affecting ALL The Alfatross' instruments, one that would that would teach me the difference between a generalist instrument restorer and a truly expert one--and set me back another month! To be continued in "Surveillance Functions Part Two" . . . .