Using the 'standard' autometer 6 gauge set. Very old school carbed SBC, with a Performance Distributors/Davis Unified Ignition HEI (includes coil).

Two gauges don't work - the tacho and oil pressure.

The oil pressure gauge did work initially, but on subsequent starts it shows 0, and there is no detectable voltage from the sensor. Do they really break that quickly? I assume there's nothing special about this sender and I can go ask at the local parts counter?

The tacho has never worked, but the wiring is so simple I may be missing something. Is it to do with the HEI? I did flick the switch in the gauge to V8 mode before I fired up.

Any tips?