Caught some luck today on the original tach. Actually works!!

[NCtrueconservative]

My tach in the rallye dash didn't work, and I feared that like so many others, it was just toast.  I got on my back and squeezed my way under the dash to find the wire that sends the signal to the tach, was not the same color as the wire connected on the neg side of the coil.  The only wire on the neg side of the coil was black and yellow, while the one on the tach was white or grey (couldn't tell) but it didn't run through the firewall like it was supposed to.  So, I just unplugged it, plugged in a new wire, and ran that out to the negative side of the coil and to my surprise, VOILA!! The original tach works like a charm!!!! Now I can keep tabs on those RPM's.  A 5 minute fix   

[Bullitt-]

Don't ya just love it when things work out?   

[NCtrueconservative]

Don't ya just love it when things work out?   

Yes I do, even though they aren't as frequent as catching bad breaks  Still, its these little wins in life that keep a man going I reckon

[dodj]

My original tach is still working too! Hard to believe after 40 years.
Glad your is still workin' 

[NCtrueconservative]

couldn't believe it when I saw that needle move. Seems to be pretty accurate as well from what I can tell. 

[brads70]

NICE! 

[hooD]

     Way to go...just like a real detective.

[burdar]

If I were you, I'd have it tested to see how far off it is.  The factory tachs are usually way off to the high side.  The guy that rebuilt my gauges was shocked that my tach was pretty accuarate.  That rarely ever happens he said.

[DAYLEY/CHALLENGER]

I had to unhook my tach.........I would be running about 45 MPH and the tach would show 8000 RPM....and it was connected to the neg side of the coil............