SwedCharger67
Well-Known Member
Maybe slightly OT but I thought it might be interesting info:
Here is a test of 2 original 1967 Charger tachometers. I did the test a few years ago and used a frequency generator to feed the RPM to the tachometers. The frequency generator ( and thus the test RPM) is very accurate.
IIRC there is only one potentiometer inside the tachometer, so only one RMP can be chosen for showing the correct RPM.
In the tables you see tachometers A & B.
Two test RPMs are used, 2k RPM and 5.7 k RPM.
Setting the calibration point at 2k RPMs you see that A is 1000 RPM off at engine RPM 5700.
Setting the calibration point to 5700 RPM, we can see that A is off 500 RPM @2000 RPM, and tachometer B is off 200 RPM @ 5000.
So, tachometer B is way more accurate after calibration than tachometer A.
