Tachos

[StewartG]

Does anyone know how to connect the standard tacho to an aftermarket 3D ignition system such as weber alpha? I connected up as per webcon's advice and it worked for a few miles and then the tacho burnt out. The advice was, if the distributor is being used, connect the -ve side of the coil directly to the -ve/signal terminal of the tacho. Unfortunately the results were somewhat incendiary.

[StewartG]

Strangely the tacho wasn't as burnt out as I thought. Having installed the weber alpha I went out for a test drive and after a few miles the engine cut and the tacho smelt burnt out. I disconnected the tacho the engine restarted and I did 50 more miles without any further problems or a tacho. The next day I set about tracing the problem thinking either my wiring from the coil to the tacho had shorted to earth or the tacho was shorting internally. Weirdly when I reconnected everthing the engine started and the tacho worked fine and has done ever since, touch wood. The only explanation I can come up with for this is that the tacho shorted internally, causing the engine to die, the shorted component probably a capacitor continued to short and burnt itself out hence the smell and ended up open circuit. There's several capacitors in parallel in the tacho and it appears to work just as well with one less, if anything the recent under-damping of the mechanism seems improved. Ain't life strange?