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How do I bench test my factory tach?

troyintahoe

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Looking to bench test the tach on my 73. It is currently out of the car. I want to rule out any issues before final assembly on my dash. Troy
 
Wire it up to a running car on the fender.

I "Bench" test tachs like this on my Duster. It's easy enuff with clips on the wire.
 
Tach

I have no idea where to run the wires. The tach had two wires connected to it in the dash. I assume one goes to the positive side of the coil and the other is a ground?

I am no mechanic and I need a little more..... Thanks, Troy
 
Is this a factory tach or a Sun or something? The factory tach for my 69 RR has two terminals and one goes to battery pos and the other is the signal, or coil neg. Ground, or battery minus, is done through the tach housing. You will need a car with a conventional points ignition to test it.
 
Tach

It's the factory tach in my 73 Roadrunner. It's not aftermarket. It's in the second circle from the left, in my ralley dash. 73 doesn't have points, so I'm still confused. HELP
 
I just calibrated my tach, yesterday, it also only had two wires. I hooked up the blue wire to positive and the other to negative of the coil. I have electronic ignition. I then grounded the frame of the tach with a jumper wire. gerry
 
Like everyone says, 12 volts to one wire and the negative coil wire to the other. And ground the frame of the tach. I did mine this weekend after I installed the Real Time Engineering tachometer kit. :sSig_goodluck:

Dan

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Be careful hooking it straight to the battery, because if your battery runs hot (higher than 14 volts), it could spike the tach. The best bet is to find a switched 12V source. You should be able to get that off of your fuse box under the dash. You need to do this anyways when you put it back in the car. Otherwise, it's just like everyone else said, 12V to the back of the tach, wire from other terminal to the "-" stud on coil, and ground wire from the case of the tach (wrap wire around one of the screws that mount it to the dash) to a ground on the car.
 
The Spade terminal on the back of the tach goes to the negative side of the coil (signal) gray wire.

The longer stud goes to 12v switched power. (blue harness,goes to fuse block for acc.)

The case is ground.

My experience with the "Real Time Egineering" circuit board, is that all it does is make the pointer "move",so most people "think" they fixed it, I've checked probably 50 tachs using those, and "All" of them were inaccurate,
and if you have a bad Meter,it won't work at all!

I used to work at Redline Gauge Works www.redlinegaugeworks.com feel free to contact me regarding gauges/tachs/clocks.
 
How do you bench test this tachometer from a 1979 Chrysler 300! Thanks in advance, Tony Tee.
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