Need advice for "Tach Bounce"?
 

I noticed last weekend that the tach in my 914-6 was acting up. After a bit of driving, it would jump around in the 3-5k range. Usually while accelerating, it would stop moving at 3K, then jump to 4-5k, then fall back to 3k. I recall someone telling me decades ago that "tach bounce" was usually the result of failing or bad points.

I hope to poke around this weekend. I was going to start with checking grounds (related or not, my fuel gauge is a little bouncy too) first - coil, battery, then maybe grounds on the back of the tach?

I also need to go through records. It could be now a couple thousand miles since the last time the car had points checked/gapped.

Otherwise, the engine runs nice and smooth. No hiccups or issues in running through the rev range, just the tach not working quite right.

Car is stock 914-6. 2.0L motor. Marelli Distributor.

Thoughts?

That happened to me. I had an MSD unit go bad. Sent it to MSD and they fixed it.

Alternator/regulator issues can cause tach issues too.