Where can I find details about a Cambridge Scientific Instruments Fuel/Air ratio Indicator?
The 11622-1 is a type A-7 single-engine exhaust gas analyzer. You can see it here on page 8. The instrument just tells you if the fuel/air mixture is too rich or too lean. Electrical inputs are simple; 12vdc and ground. Any competent instrument technician can open it up and see which pin is what. But that's only the beginning... the system includes tubes and an analysis cell, and the cell is probably pretty much useless by now, if it is still installed, but you can always try your luck.