tachometer cable rpm

[mnahon]

Hi,

I'm wondering if anyone knows whether the tachometer cable spins at engine rpm, or some fraction of that? I'd like to try to set up a bench calibration of the tach similar to what Pawel did for his speedometer.
https://www.sl113.org/forums/index.php?topic=36590

Thanks,

[mnahon]

I'm going to answer my own question: it looks like the tach cable spins at half engine speed. I tried driving the tach with a couple of different drills whose speed I knew. In both cases, the tach read about twice the rpm of the drill.