i removed the 4 bolts already but there appears to be a larger 12 point bolt deeper in the pulley that i cannot remove. i have tried ratchets with pipes on it. i have also used my impact gun with the regulator bypassed to 150psi and it will not remove the bolt. i have tried this on 2 motors and neither will budge. is this a bolt that is supposed to be removed? if so, any advice? i have already soaked it in PB blaster for 2 days, and tonight i applied so much heat that i set the crankshaft on fire. i am at a loss. please help me!