Is tach wiring in standard rally gauge harness?

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FC7Demon340

FC7Demon340

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I have started the restoration of my dash. My 71 Demon 340 came with the rally gauges but no tach. I have acquired a Tach cluster to convert my rally gauge dash. My question, is the tach wiring already in the rally gauge harness or am I gonna need a separate harness for the tach? Need some help figuring out how to hook the tach up. Thanks
 
The tach was a separate harness regardless of whether your car came with one or not because it was optional. The main harness was the same with or without a tach.

One wire goes to the coil - , the other goes to a switched and fused 12v source at the fuse block.
 
72bluNblu said:
The tach was a separate harness regardless of whether your car came with one or not because it was optional. The main harness was the same with or without a tach.

One wire goes to the coil - , the other goes to a switched and fused 12v source at the fuse block.
Click to expand...

I see a Tach harness for A bodies in the classic Industries catalog but says it's for 1965.
 
Don't forget the lamp. The tach wire on everything went through a separate grommet in the firewall, much like the clutch safety switch
 
FC7Demon340 said:
I have started the restoration of my dash. My 71 Demon 340 came with the rally gauges but no tach. I have acquired a Tach cluster to convert my rally gauge dash. My question, is the tach wiring already in the rally gauge harness or am I gonna need a separate harness for the tach? Need some help figuring out how to hook the tach up. Thanks
Click to expand...
Depends. A few years/models the tach signal came firewall using one of the bulkhead connector cavities. The FSM will (usually) show how it was done for your year and model.
 
Options for this gauge pod were a blank, a tach, a clock, a performance indicator (vacuum gauge). So tach is accessory. Wires probably not in your harness. Some Formula S B'cudas and some 340 Demons, typically manual 4 speed, did have these wires in the car built with the tach option.
These wires attached to the gauge itself. 2 studs on the gauge, no markings but one shorter than the other. Short = sender or signal. The longer gets 12 volts from accessory fuse. Your fuse box may be missing fuse and a clip for 1 end of that fuse.
 
Found this harness on Year One and Classics sites. Says it's for a 65 A body. But the connections look just like the connections needed for the back of my tach. So I assume it will work?

Screenshot_20200202-083509_Samsung Internet.jpg
 
FC7Demon340 said:
Found this harness on Year One and Classics sites. Says it's for a 65 A body. But the connections look just like the connections needed for the back of my tach. So I assume it will work?

View attachment 1715463331
Click to expand...
Yep. Before you hunt a fuse clip for the accessory port of your fuse box... Your windshield wiper switch may have a unused spade terminal that serves the same purpose. Pick up the switched and fused 12 volts there.
 
FC7Demon340 said:
Found this harness on Year One and Classics sites. Says it's for a 65 A body. But the connections look just like the connections needed for the back of my tach. So I assume it will work?

View attachment 1715463331
Click to expand...

the 65 and 66 tach are way different than your 1971. I wouldn’t buy that harness. Like 72BluNBlu said it would be super simple to make your own. It’s 2 wires.
 
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