I am throwing alternator belts at RPMs above 5K. it is much worse in first gear than in higher gears. If I take it easy the belt will invert instead of come off. I have a 406 small block in a 79 Z28 at about 500 HP. I have replaced the crank pulley, alternator and all three of it's brackets. It is head mounted. Pulley alignment looks fair, not perfect. The alternator looks like it is a bit forward from the water pump pulley. I have tried all combinations of washers behind the alternator adjusting bolt. The straighter I get it the worse it throws belts. I put a spacer behind the water pump pulley, which made both the alternator and power steering look perfect and started throwing the power steering belt as well, so I took it out. It appears that some misalignment is required for the power steering belt to stay on. I really do not want to go out and buy a serpentine arrangement. Has anyone got any ideas?