Book excerpt: New revised and updated edition, complete with extra illustrations, of this best-selling SpeedPro title features expert advice on building and modifying classic/retro 2-valve per combustion chamber cylinder heads for maximum power, economy and reliability. Topics include: Horsepower and torque Equipment and tools Airflow Building a flowbench Valves Unleaded fuel conversion Camshafts Exhaust system Ignition Cylinder heads, except 2-stroke. Written by two expert engineers, who share their extensive knowledge and experience, How to Build, Modify & Power Tune Cylinder Heads is a complete practical guide to successfully modifying cylinder heads for maximum power, economy and reliability. Using understandable language and clear illustrations, they explain everything you need to know about building, modifying and power tuning cylinder heads. The content applies to almost every car/motorcycle with a 4-stroke engine. Also applies to road and track applications.