1971 Tach To HEI.

[warrentech]

I have a 1971 GT with a 140 and a 1977 HEI and wanted to know if the stock 71 tach will work with that and how to hook it up. The car runs great, just trying to fix the small stuff. Thanks for the help.

[spencerforhire]

The HEI cap usually has it's 2 terminals marked as +(or ign) and -(or tach); just crimp an ordinary female spade on the brown wire from the cluster and hook it to(you guessed it)-the empty tach terminal. There may be a capacitor screwed to the firewall with the brown wire run through it; it's there to filter out interference. If you can't get the tach to work you can bypass the filter cap to see if it's broken, but going without it may cause erratic readings.

[warrentech]

This 140 HEI is not like a V-8, it does not have a cap that has a tach connection. The wires come out and go to the coil that is mounted on the engine. There are male terminals on the coil that are not being used. The wiring charts do not show the tach hookup on the HEI 4 cylinder H-bodys. If some one has a factory 140 4 cylinder, HEI with a tach and can see where their wire is connected that would help me out. Thanks for the help.

[bugdewde]

My '73 has HEI ignition..... I'll get a pic of it when I get home later today. I may have a pic of it in one of my threads concerning the head rebuild, though........ Hmmmmm.
I know it's plugged to the distributor in the TACH location like mentioned above.... but it's been a while since I've laid eyes on it.
Not sure if it's got a capacitor or not......

[spencerforhire]

My bad for not remembering that the 140 had a separate coil; the tach goes on the white(or brown)-whatever terminal on the coil that does not have the pink + ignition hooked to it. It might even be marked as (-).