Book excerpt: Graham Hansen, author of the best-selling SA Design title How To Build Big-Inch Chevy Small Blocks, takes the mystery out of camshaft and valvetrain function, selection, and design. He covers camshaft basics, including a thorough explanation of how a cam operates in conjunction with the rest of the engine and valvetrain. He discusses technical terms like overlap, lobe centerline, duration, lift, and cam profiling. Comparisons between roller and flat-tappet cams are addressed and analyzed. This book covers rocker arms, lifters, valves, valvesprings, retainers, guideplates, pushrods, and cam drives, as well as detailed information on how to degree a cam and choose the proper cam for your application. Finally, matching cams to cylinder heads, analyzing port flow, and proving it all through dyno tests round out this informative volume.