Eric;
The old tachs are expecting to see a much wider pulse width in order to work
properly. A CD ignition provides only a very short firing current spike.
WRT rev limiters, I found an older Mallory unit, with a variable pot for
setting different rev limits. THis allows me to easily change it for
practice vs. race for example. Most rev limiters only short out the coil
intermittently to eliminate ignition pulses. Not sure if they're compatible
with your particular CD unit, as shorting the output of the CD would more
likely damage the CD than the rev limiter.
Most modern tachs likely work with both CD or inductive type ignitions. I've
seen a few guys go to the trouble of putting modern internals in the old
gauge face and housings. I chose a ProMeter unit that was close to the same
size as my old Smiths one.
Regards,
Myles H. Kitchen
1965 Lotus Cortina Mk1 #128
|