I recently built my B16 for an all-motor setup. It was converted to OBD-1. After the build I installed the aforementioned tachometer only to find the needle will jump to random points when the engine is between 3 and 4 thousand RPMs. Anything above or below that reads accurate. Autometer told me it was my magneto ingnition. Help?

 

Might want to check out the wires on your ignitor in your dizzy. If those terminals are loose on there your tach will jump around a good bit. Does the car have a stock tach too, and if so does it jump?

 

I can almost guarentee you have a loose coil wire or an intermittent connection--I had the same thing happen many years ago and that is always the problem.

 

stock tach works fine. The coil is a MSD Blaster 2. The wire is seated properly. Any other suggestions?

 

The distr. is getting ready to take a ****. Get a new distr.

 

Let me reiterate myself; the stock tach works fine.

 

There is a bad connection somewhere connecting your Autometer tach to the coil--your stock tach is not as sensitive as the Autometer so it may not show an intermittent connection like the Autometer would. I would use a DVOM and check resistance in your connection wires from the Autometer to the coil.