Tachometer wiggle, Just started yesterday Options

[BiG bOgGs]

Yesterday while on the way to and from work my tach needle started to wiggle upwards from its usual reading of about 3400 rpm. Until yesterday I had no problems at all.

On the way home I noticed that if I was under moderate acceleration or deceleration the tach read steady. When I was cruising at a constant speed is when the wiggling would start.

Any suggestions on how to track down the problem and fix it? (IMG:style_emoticons/default/poke.gif)


Jim

[Spoke]

The tach has very little dampening of its needle and also takes input directly from the engine coil. Both of these items will cause some bounce in the tach needle.

So if you have issues with your points or plug firing, the tach will bounce like crazy. Your issue could be pointing to something happening in your engine's ignition circuit.

Does your engine have points or electronic ignition like Pertronix or other? Does the engine hiccup when this happens? If you have an issue with your engine's performance, this could be why the tach jumps.

If your engine is properly tuned and running good, in normal operation the tach needle will bounce somewhat when you rev the engine or shift gears. You can add dampening to the tach by placing a 2000uF capacitor directly across the tach winding but this involves taking the tach apart. I used a 3300uF capacitor on mine and the needle is rock solid like modern cars. 3300uF is a bit much as the needle is a little bit lethargic when the engine revs go down.