Nickelplate Posted July 14, 2022 Share Posted July 14, 2022 I have looked at https://www.garysgaragemahal.com/tachometers.html to check this, but I haven't been able to figure out the "extra ground that changes it to 8cyl mode". Is that done somewhere inside the gauge cluster? Is it under the dash? Or is it the Black/LtGreen ground wire #60 (in connector C-323)? Or somewhere else? My Tach is consistently showing 500RPM lower than actual. I'm wondering if I need to run a ground to that wire #60. There are a lot of wires I'm no longer using after my Edelbrock Pro-Flo 4 install, and that is one that is now not connected to anything. Link to comment Share on other sites More sharing options...
Gary Lewis Posted July 14, 2022 Share Posted July 14, 2022 An 8 cylinder ignition harness has that wire in it and it grounds the 8 cyl terminal on the tach. A 6 cyl harness won't have it. But, 500 RPM off consistently sounds like just an error in the tach. You can pull the needle off and put it back on 500 off. Link to comment Share on other sites More sharing options...
Nickelplate Posted July 14, 2022 Author Share Posted July 14, 2022 An 8 cylinder ignition harness has that wire in it and it grounds the 8 cyl terminal on the tach. A 6 cyl harness won't have it. But, 500 RPM off consistently sounds like just an error in the tach. You can pull the needle off and put it back on 500 off. Thanks, Gary! Helpful as always! I will ground wire #60 and then work on my Tach. Link to comment Share on other sites More sharing options...
mat in tn Posted July 16, 2022 Share Posted July 16, 2022 Thanks, Gary! Helpful as always! I will ground wire #60 and then work on my Tach. BE CAREFUL WITH THAT NEEDLE . god they are fragile Link to comment Share on other sites More sharing options...
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