The instrument panel tachometer must not be considered accurate until it is correctly calibrated using a known good hand held strobe-type or photo electric tachometer.

How do you calibrate a digital RPM meter?

It is very simple to use, For a non-contact measurement, just point or aim the laser of the tachometer on a rotating shaft with a reflective tape stick to it. Ensure a steady hand while aiming to get an accurate reading. Ensure the distance from the measured part is not more than 24 inches for accurate measurements.

How do you calibrate an analog tachometer?

Run the motor at 1,000rpm on the timing light readout, and compare the reading on the timing light to the reading on the boat tach,adjust if necessary, then repeat at 2,000, 3,000, then 4,000.