If you are using an electronic Auto Meter speedometer, no calibration is necessary. The interface module is calibrated to 16,000 ppm (pulse per mile) and all Auto Meter electric speedometers are calibrated the same. For other speedometers, simply hold the calibration button until the needle gets close to but not over 80 mph; once released the needle will drop back down. Within 5 seconds, repeatedly tap the button until the needle reads 80 mph—that’s it. If you exceed 80 mph, then you will have to repeat the process.