Either use the allen wrench with the box end wrench method (allen wrench to keep the rotor from spinning, box end to losen the nut) or just use an impact wrench. The rotor wont even know what happened when you pull the trigger, the nut will just come right off.
If the nut is a bit tight, then put the alternator on a piece of cardboard (or ground), put your foot on the fan, then whack it with the impact wrench.
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1969 Base Camaro
Vortec 355, Perf. RPM, Demon Carb., TH-400
All sheetmetal is NOS GM
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