I don't think you have the right thing....if you take the starter off you should see the teeth of the flywheel...I am just guessing this, i have never personally done this for this engine. So take the starter off and jam a screw driver in the teeth of the flywheel to hold the engine. You may want to get someone to help you. One person hold the screwdriver in the flywheel and the other undo the nut on the front of the harmonic balancer.

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George Carstens