The high point on the cam generally corresponds to the keyway. With the rubbing block of the breaker at that point, the gap is set at 0.020". The double raised lines on the outside rim of the breaker base is used IF you have the factory timing fixture. The results are the same. The two stamped lines you see on the throttle cam are for throttle syncronazation. As the magneto advances, it picks up the roller on the carburetor throttle arm. The throttle plate (AKA butterfly valve) should just start to open when the roller is between those two lines. It is adjustable by loosening the port screw under the throttle cam. (Port its the left side of the boat when facing the bow [front]) That would be the right when facing the motor.
top of magneto
bottom of magneto
Timing tool
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