Dont sacrifice your acceleration due to a heavy flywheel. For 1955-1985 internally balanced 55-85 small block Fits Chevy applications. Made of 1045 billet steel. 168 tooth. 21.7 Lbs. Use 11" clutch. 55-85 2 Piece rear main SBC. Note: Not for use with stock clutch disc as springs on friction disc hub will not clear flywheel bolts. Not For Use w/Stock Clutch Disc This flywheel is not compatible with stock type sprung hub clutch discs (5 or 6 springs). A performance type disc with 8 springs must be used. Or aftermarket flywheel bolts like ARP or Mr. Gasket will work with the 5 or 6 spring clutch. Performance and SFI-approved flywheels must be used with performance clutch discs only. Use of a stock-style clutch disk with a performance flywheel will often result in insufficient operating clearance between the disc hub and flywheel bolts. Not For Use w/Stock Clutch Disc This flywheel is not compatible with stock type sprung hub clutch discs (5 or 6 springs). A performance type disc with 8 springs must be used. Or aftermarket flywheel bolts like ARP or Mr. Gasket will work with the 5 or 6 spring clutch. Performance and SFI-approved flywheels must be used with performance clutch discs only. Use of a stock-style clutch disk with a performance flywheel will often result in insufficient operating clearance between the disc hub and flywheel bolts.