Tach bench test

[nakabrd]

I bought a '70 Challenger 440 RT with Rallye gauges. It wasn't running and I have the dash apart on my bench. Can anyone tell me how to bench test the Tach? Thanks for any help.

 

[Adam]

Now would be a good time to upgrade. http://rt-eng.com/rte/index.php/RTE_67-74_Tach_kit

I have done two of these kits, very easy. Their directions may help you.

http://rt-eng.com/rte/images/c/c7/TachManual67-74_REV13.pdf

a) The case of the tach to the case of the alternator to get a good ground
b) The long stud on back of the tach to the large +12V terminal on the alternator (Be
very careful not to allow this jumper to touch the car or the case of the tach, as it will
spark and cause problems if you let it touch ground).
c) The short stud on the back of the tach with the spade terminal should be jumped to
the minus side of the coil (unless you have a MSD ignition, in which case it should be
jumped to the MSD tach output).
4
After hooking up these three jumpers, and starting the car, then the tach needle should
move as you rev up the motor.

 

[nakabrd]

Thanks for your reply Adam. Good idea to upgrade, I didn't know these kits existed.