Ultra-Light SFI Certified Billet Aluminum Flywheel for the Harbor Freight Predator Hemi weighs 1.75 LBS, is stock diameter and the lightest flywheel available. This flywheel is made from the same quality materials and with the same attention to detail and reliability that has come to be expected from ARC. For optimum performance we recommend running with a balanced rotating assembly. You will need to put a few washers between the coil and the engine to center the coil over the magnet. Set coil gap at least .030". IMPORTANT: If you want to use cooling fins with this flywheel, you will need to buy part number DJ-1175. The fins that come on the Harbor Freight engine will not fit properly. Now featuring an 8 degree timing advance built into the keyway. 32 degrees BTDC.