For the Autokraft labeled Instruments i received the following information from Andy at Speedy Cables:
Hi Uwe, the gauges are made by Stewart Warner and they do not use a voltage stabilizer they need 12 volts feed and one connection to the sender. The fault you describe is the stabilizer operating and shutting of voltage to the gauges. The tacho has a Stewart Warner dial and pointer but a Smiths movement. + must be connected to 12 volt supply – must be connected to 12 volt neg supply, the other terminal is connected to the negative side of the ignition coil. You may have a problem with calibration as the pointer was never made for that pointer and the balance could be out, please contact me if you need any further assistance, Regards
Andy Barraclough
Director
Abercrave,Swansea SA9 1SQ
I tried to follow his advice but found out that the tachometer works in my car only connected to the + terminal of my ignition coil.
Again it is not the Smiths instrumentation I'm talking about its is the Motorkraft labeled series of gauges used in the straight dash cars.
Speedy cables is always a good support and helping hand, especially for the mechanical cobra instruments i used the last years.