How to test a factory tach

[antonellomopar]

I am restoring the rallye gauges in my Challenger. Have tested everything with good results, but don't know how I could test the tach. Could I simply connect the spade connector to the neg side of the coil, and the other connector to the battery of another car? Thank you

[MoparLeo]

Did you replace the old tach board with a new modern one ? That is the way to go and easy to calibrate. Haven't received your hinge cores for rebuilding yet.

https://rt-eng.com/index.php/67-74_Tach_Board_with_Calibrator_Built_In.html

[antonellomopar]

No, I dont want to replace anything...I have always used the stock tach without modifications, knowing that the RPM is not very accurate. I am using the stock distributor, so want to keep everything as dome by Mopar. As for the door hinges, my bodyman has already fixed the one needing repair, so there was no need to send also the good ones. Thank you anyway for the offer.
I only want to see if the tach is working before I install the giauges in the car.

[Jay Bee]

Could I simply connect the spade connector to the neg side of the coil, and the other connector to the battery of another car?

Yes, and ground the body of the tach. I've done this and, just to double check the connections, I looked at the colored wiring diagram.

This Mr Heaterbox Youtube video has some info too even if they're using a tic-toc-tach.

[antonellomopar]

Hi Jay, thank you for the help. WIll try tomorrow

[moparroy]

I hooked mine up to the coil on my '85 Daytona - course being a 4 banger it only record half but shows it is working - you need an older car with a distributor / single coil and open coil terminals makes it easier.

[Vvellajr]

Spade to negative coil, lug to accessory power and i believe you have to ground the tach case.

[antonellomopar]

many thanks to all who replied. Will try in the next few days and see if it works.