75 Tach Calibration
Thread Starter
Cruising
Joined: Sep 2009
Posts: 11
Likes: 1
75 Tach Calibration
Hello, I had to install a new tach circuit board for my 75 auto L82. I didnt re-calibrate it correctly when I first installed it, and now "idles" at around 3k rpm. What is the easiest way to reset this to 0? The instructions say to hook up 12v to the board, then unattach the needle and set it to zero. If I were to run 12v right from a car battery to this board, wouldn't it just fry the board? I have the tach out on my workbench, and want to make sure it is calibrated correctly before I put it back in (as I'm sure a lot of you know is a pain in the @ss).
Thanks for the help in advance,
Tom
Thanks for the help in advance,
Tom
Instructor
Joined: Mar 2002
Posts: 140
Likes: 1
From: east hampton ct
I just did my 75 two weeks ago. Simply hooked up the tach to the lawn mower battery, 12 volts, noted where the needle was, pulled the needle off and reset it. It took three or four tries to get it right but it seems to work fine. If you have a dial back timing lite I suggest hooking it up and testing the tach with the motor running prior to reassembling the dash.
