Testing a tach

[honedout]

I have 3 different tachs for my boat. Trying to get one to read correct. 2 are OMC tachs and one is a teleflex. Thay all read different.By 300-500 rpm. I have them set on the 4 position for my motor. 1987 seadrive 1.6. Is there a way to test and calibrate a tach or otherwise check the rpm on the motor. One is reading what i think is close but i want 100% accuracy for testing some props i have.

 

[Joe Reeves]

Re: Testing a tach

The tachs operate off of the pulse rate of the charging systems of the OMC engines. The charging systems emit six (6) pulses.<br /><br />The dial on the back of the tachometers must be set to six (6) regardless of the number of cylinders.