You can try adjusting the potentiometer on the original tach board. Sometimes this will make the tach read correctly, sometimes it won't. It depends on the condition
of the original 30 year old pot and the electronic components on the board. One problem with the original tach electronics is that the pot is not sealed, so they end up getting a lot
of gunk in them. You have heard the results of this if you ever tried to use an old radio and when you adjusted the volume control you would hear a lot of static. Same deal here.
If you can't get the old tach board to read correctly, then I sell a new one with modern semiconductors that will fix your problem. It uses a sealed pot that won't get corrosion. In addition
my board will work with MSD ignition. Also I have a regulator on my board so that the tach reading won't fluctuate as the voltage on the battery goes up and down.
Good luck!
GregGarner
www.rt-eng.comHome of the mopar tach and clock repair kit
