BBC Ultra Pro Magnum XD R/A - 1.7 7/16

The COMP CAMS BBC Ultra Pro Magnum XD R/A 1.7 7/16 rocker arm is engineered for big block Chevy engines demanding high-RPM reliability and consistent valve train geometry. Built for serious enthusiasts and professional engine builders, this full roller rocker arm replaces factory stamped steel designs with precision-machined performance hardware. The 1.70 mechanical advantage ratio delivers enhanced valve lift and improved flow characteristics, making it essential for naturally aspirated and forced-induction BBC applications pushing past 6,500 RPM.

This rocker arm features full roller construction with hardened chromoly steel construction, eliminating the friction losses and wear patterns inherent in traditional stamped designs. The 7/16-inch stud mount interface integrates seamlessly with standard BBC cylinder head configurations, while the roller contact surface reduces parasitic drag on pushrods and allows faster valve events without sacrificing stability. The precision 1.70 ratio amplifies camshaft lift by 70 percent, meaning a 0.500-inch cam lobe translates to 0.850-inch valve lift—critical for maximizing intake and exhaust flow without exceeding spring pressure limits. Weighing just 0.7 pounds per arm, the lightweight chromoly construction minimizes inertial mass for cleaner RPM transitions.

Ideal for dedicated street engines, circle track racing, and dyno-proven performance builds, the BBC Ultra Pro Magnum XD rocker arm suits 396, 427, and 454 big blocks running roller cam profiles and aggressive valve timing. Installation requires compatible BBC cylinder heads with standard rocker stud bosses and pushrods sized to your specific lift requirements. Order as individual arms or complete sets; proper valve lash adjustment and spring seat checks are essential before engine startup to ensure reliability and longevity under sustained high-RPM operation.