BBC Solid Roller Cam 47S 321R12

The COMP Cams BBC Solid Roller Cam 47S 321R12 is a purpose-built drag racing camshaft engineered for big block Chevy engines equipped with 4/7 swap configurations. This mechanical roller cam delivers 0.748 inches of lift on both intake and exhaust sides, with a 321-degree intake duration and 336-degree exhaust duration profile, optimized for peak power in the 5000–8500 RPM range. The 112-degree lobe separation angle (LSA) creates an aggressive powerband suited to dedicated competition applications where maximum cylinder filling and scavenging efficiency drive performance gains.

The mechanical roller design eliminates the friction losses inherent in flat-tappet profiles, translating specification into repeatable dyno numbers and consistency across multiple heat cycles. The duration split (321/336) favors exhaust scavenging, a critical advantage in bracket racing and heads-up competition where every fraction of a second matters. The narrow 112-degree LSA produces strong overlap characteristics and a pronounced idle signature—indicators of the cam's single-purpose focus. COMP Cams' manufacturing tolerances ensure durability even under the sustained high-RPM operation and aggressive valve events characteristic of drag racing environments.

This camshaft is intended for serious competitors and engine builders preparing big block Chevy platforms for competition duty. The 47S profile is not designed for street manners—owners should expect elevated idle quality, significant overlap at low RPM, and a powerband floor around 5000 RPM. Installation requires proper valve train geometry verification, lifter preload adjustment, and potentially updated ignition timing calibration. Buyers should confirm their engine block, cylinder head port configuration, and intended redline before purchasing to ensure optimal cam timing and component compatibility.