Ok, I just put a sonpro tach in my car, but I don't think it's working right. For one, when I get to about 25 in first, it says I'm only at about 1700 rpms. I know that can't be right. I don't think I have seen the needle over 3 grand, and I have been winding that baby tight(like I always do). You know. Shift 1-2 at 25, 2-3 at 45, 3-4 at anywhere between 60-75. It should be getting pretty close to 6 grand, but it doesn't even get close. I put the wires on the right spots. The wire that controlls the tach put on the tach wire in my harness behind the cluster. Red wire on with the turn signal circuit, white with interrior lighting, and black to negative battery terminal. Has anyone had a problem like this, or is there anyone who knows anything about this that can help?

wired as v-8 still or 6 i bet had problem like that before with wiring tach find what wire to cut

I spliced it in with the factory tach wire. What the Haynes manual said was the tach wire anyway. *sigh* My friend knows someone who does tachs for a living. Maybe I'll see if he can hook me up.......

On the back of the tach there are two small wires looped out where the 4 wires come out of the back. You need to cut both of these wires to get it to read correctly!!

I just went out and looked for those two wires, didn't see any wires, but guess what I did see. A small switch that I over looked while installing it. What did the switch say? 8,6,4. Hmmmm. Switched it to 4 and it seems to be working just fine now. I will let you know more tomorrow. I have been drinking some tonight and didn't do anything but start it up to see if it was regestering more than 500 for the idel like before and it is now at a grand for idle. You would think it they would have said something about that in the instructions...... Thanks for the help fellas

I never did get back to y'all on this. The tach works fine now after switching the switch.

I never did get back to y'all on this. The tach works fine now after switching the switch.

I have the same tach, and its set to 4 cyl, but my rpms are still low. Did you have to use a tach adapter? I have my green wire attached to one of the three wires going to the distributor cap, is that wrong?