I just recieved a new tiny tach TT2A model for my 15hp merc 2-stroke and they doesnt make "2C" model anymore. Now they make a tinytach and adjustable degree reading for lawn mowers to a V8 engines. I dont know if my motor has 360 degree 1 spark per revolution or 180 degree 2 sparks per revolution. :-/ I tried everything with good connecting ground wire and clean the spark plug wires for better reading.....still nothing. I havent tried this model before.. I never had a problems connecting with 2C models. does anybody tried this model before? I'm going to ship it back and get another one. MAybe this one is faulty tach..