Mike, it is seldom Idisagree with you, but I have to when you say not to use a tach. Once you are used to the engine, and know how it soundswhen running right, the tuning by ear is OK. A new prop size though requres the tack come out of hiding. For a new (or new to you) engine, espically your first four stroke, a tach is mandatory for the first setup. On an engine that needs a long break in like the Magnums do, you will need the tach to get the right richnes during the longbreak in. It a cheep investment, anddoesn't take much room inthe flight box.

Don