COMP Cams CL31-601-9 Mutha Thumpr 283/301 Hydraulic Roller Cam Kit for Small Block Ford

The COMP Cams CL31-601-9 Mutha Thumpr Hydraulic Roller Camshaft Kit delivers the aggressive, lopey idle sound and feel that performance enthusiasts crave, while still providing strong street and strip power for Small Block Ford engines. With intake duration of 283° and exhaust duration of 301° (advertised), this cam kit is engineered to produce a distinct, thumping idle character with serious mid-to-upper RPM power delivery.

The Mutha Thumpr series features COMP Cams' proven asymmetrical lobe design — wider exhaust duration creates that signature uneven idle pulse while maximizing cylinder scavenging for real-world performance gains. The hydraulic roller lifter design eliminates the need for regular valve lash adjustments and offers reduced valvetrain friction compared to flat-tappet designs.

Key Features:

• Advertised Duration: 283° Intake / 301° Exhaust
• Duration at .050": 236° Intake / 248° Exhaust
• Valve Lift: .536" Intake / .544" Exhaust (with 1.6:1 rocker ratio)
• LSA (Lobe Separation Angle): 107°
• Hydraulic roller lifter design for low maintenance and reduced friction
• Aggressive Mutha Thumpr lobe profile for a distinctive loping idle
• Designed for Small Block Ford (SBF) applications
• Complete kit includes camshaft, hydraulic roller lifters, and installation hardware
• High-quality billet steel construction for durability and long service life

The CL31-601-9 kit is best suited for performance street, street/strip, and hot rod SBF builds looking for maximum sound and strong top-end power. Recommended for use with compatible valve springs, timing set, and push rods — verify component compatibility before installation.