To replace the original tachometer with one that has a built-in hour meter, I need to know the pulse rate per revolution and the take-off ratio of the sensor on my 2GM20F. The service department at Hunter Marine, with help from Yanmar, informed me that the pulse rate is 97 pulse per revolution but the take-off ratio was not available. There are 174 possible settings on the new tachometer so it isn't likely I will find it quickly by trail and error. Does someone know what the take-off ratio is or how I might go about finding it? Phillip Coker Silent Dancer