Coil/Tach/Dist Question

[wmpwilson]

77 Spider 1800 w/ dual points.

Car starts and runs fine. Tach does not work. I traced wires to coil and found that the dist & tach wires were reversed, i.e., tach connected to + side of coil, dist to other post. When swapping the dist wire to + post, I left tach wire unattached. Car would not start. I attached tach wire and car runs fine, but tach still not working. My understanding from reading other posts concerning tachs and coils is that the coil should still operate fine without the tach wire hooked up. Is this an indication of a problematic Coil? If so, any suggestions on a good replacement coil? I will probably convert to electric ignition in near future........

Also, Charge light is always on, but 13.5 volts at alternator...is this related?

Thanks,

[majicwrench]

Wire on + side of coil hot with key on, comes from ign switch.
Wire on - side of coil goes to distrib and gets grounded as points close
Wire from tach goes on - side

[77SportSpider]

If the alternator is aftermarket with an internal voltage regulator, you have to do a small modification to the wiring to get the light to work properly. The instructions are on the mirafiori site here:
http://www.mirafiori.com/faq/content/alt-upgrade.html