'69 Camaro tacho

[evilzee28]

Just finishing wiring up my '69 Camaro & it's fitted with a factory tachometer. All of the wiring is as it should be, but when the ignition is turned on, the tacho bumps up to 1000 revs & stays there. There's no coil on it at the moment, but I'm fitting an MSD6AL to it. Is there anything else that needs to be wired in to make the MSD compatible with the factory tach & why does it jump to 1000rpm with the ignition turned on, thanks........Nigel

[ohcbird]

Where did you pull the signal from- the +, or the - side? Does the needle 'zero out' after you shut the key off?

[evilzee28]

Where did you pull the signal from- the +, or the - side? Does the needle 'zero out' after you shut the key off?

There isn't a coil or MSD connected yet, it jumps to 1000rpm just by turning the ignition key on, but it does return to zero once the key's turned off. Do stock GM tachs work on pulses from the coil? When fitting an MSD6AL can you just wire up to the tacho output on the MSD? thanks......Nige