Join Date: Mar 2003
Location: Columbus, OH
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Tach question with HEI module
This weekend I set about to clean up the birds nest of wiring in the engine compartment of my CJ7. While there I decided to replace my duraspark ignition control module with the HEI module. I have been running a MSD TFI coil for some time now. I ended up using a stock HEI module from a 1980 camaro with a 350.
My question -- after getting everything wired up I started the Jeep. Well, I was not happy, my tach was reading ~2K rpms and fluctuating. I shut it down for the night and looked at it again today. I started the jeep tonight and put my diagnostic tach on the motor. The diagnostic tach would read lower than my in cab tach. Both tachs were set for 6 cylinder. I ended up changing the in cab tach to the 8 cylinder setting to see what would happen. After doing that, both tachs read the same.
What did I do wrong? Or do I just have a cheap tach that broke on me??
I ended up driving around the block and the new module did seam to make a difference.