I just installed a Mallory HyFire VI-A capacitive discharge ignition on my '91 RS. It works great, but now my tachometer doesn't work. Anyone know where I can locate or how to identify my tachometer lead?

 

It's the white wire on your ignition coil harness. Hook that up to the tach output of your Mallory ignition box.

 

Cool! Thanks, I thought that might be it, but I didn't want to 'experiment' and blow something up!

 

Doh! That didn't work. Any other suggestions?

 

MSD makes at "tach adapt" coil. When I put my MSD 6A on, the tach worked unless I floored it, then the needle would drop to zero. After the tach adapt was put in, I haven't had any problems, and that's been 3 years now.

 

Yeah, the Mallory instructions said I might need one of those (though I didn't need one with the MSD-6A on my '85 Z), but my tach doesn't work at all.

 

These Tachs seem to be very intolerant to any types of primary ignition mods. I only put in an accel super coil in my 91 5.7 L Z, and the tach hasn't worked right since. I am currently looking into the location of a factory installed inline tach filter which i believe to be the culprit...
~Jack~