3/8-24" blower pulley bolt. This bolt is of the highest aircraft grade quality and will insure to give the racer the most strength in holding there blower pulleys to there engine. The bolt has the proper .400" shoulder length for a blower pulley and has a 7/16" 12 point head.
1.00" is standard for a pulley bolt with washer, if running a starter jaw the 1.125" is a good choice. Racer can pick length from drop down menu.