Hays Steel Flywheels are manufactured from certified billet material that will not break up under the stress of high RPM and severe punishment of racing. Available in weights up to 50 pounds for specialized applications, most Hays Flywheels are drilled with both the Borg & Beck and Long-Style clutch pattern. Hays flywheels are certified under SFI spec 1.1. Part No. 10-630 is a "Detroit Balance" flywheel, externally balanced to stock (counterweighted) specs. Application: 1986-93 Chevy small block w/small journal. Pressure Plate Pattern: Borg & Beck/Diaphragm 10.5" & Borg & Beck/Long/Mark-XII 11", Ring Gear Teeth: 168, Weight: 30.