Hi. I just purchased a 1982 pontoon boat with the same year Johnson 50 hp on it. I would like to add a tach to the boat so I can keep track of how good or bad its performing. I would like to know if there is a particular tach to buy and the pros and cons of instillation. Thanks in advance. Mark
A tach is not a performance gauge. It merely tells you how fast the engine is running. You mount the tach and wire it using the instructions. Your engine has a 12 pole alternator which produces six pulses per engine revolution. It is those pulses the tach is counting. Set the calibration dial on the back of the tach to 6P.