tachometer bounce when cold
 

My 73.5 T (still with CSI and CDI) has started displaying some tachometer needle bounce - especially when cold, especially at low RPMs. For example: when I start the car cold, the needle indicates more or less correctly (by ear) at 1500 rpm or above, but when I ease the hand throttle down to 1200 or so, it tends to drop to 0 then bounce back. As soon as I drive away, the indication is smooth and about what I'd expect.

As the car warms up, this gets better, so I'm suspicious of a loose connection, perhaps a faston connector that is not fully seated. Just not sure where to start looking!

There's no obvious miss, so I don't suspect the points, but I'm willing to look anywhere...

Thanks.

Check connections and also check your battery...when my battery started to die my fuel and tach guage started bouncing around

Bouncey Tachy
 

Yep, mine too until I replaced my alternator and my battery was on full charge.

Thanks, but my battery and alternator are fine, and all the rest of the gauges are solid. This is just an issue with the tach, and only at low rpm...

It's perhaps not so much that it bounces, as that it drops to zero and returns.

Clean the ignition points and check the gap.