How to hook up tach w/ Magneto

[LIVE4SPD]

I have a vertex Magneto ignition on a S/C BBC. How do i hook up a tach? The tach i have doesn't work and I'm not really sure where to start. The mageto only has one wire feeding it, (other then spark plug wires) and that is the kill switch.

Thanks!

[HWORRELL]

You can't, takes a mechanical cable driven tach ( if your mag has the provisions for it) the only other option is a tach designed to work such as midgets & sprintcars use.......

[HWORRELL]

Yup, I recken that would work, did'nt know they existed......

[LIVE4SPD]

Ok well, I have a tach on the car now it just doesn't work too well. It shows 3000 RPMS anything under 3000. Above 3000 it seems to work.

I haven't dived into it yet, I'm just trying to gain an understanding of how it works. It's a regular ol' autometer tach. So it mush be driven by one of those magneto adapters?? FYI this car was built in the late 70's.