The complete practical guide to successfully modifying classic/retro 2-valve per combustion chamber cylinder heads for maximum power, economy and reliability._x000B_ Understandable language and step-by-step instruction. Topics include horsepower and torque; equipment and tools; airflow, building a flow bench; porting; valves; valve seats and inserts; valve guides; valve springs; unleaded fuel conversion. Written by two expert engineers, who share their extensive knowledge and experience to explain everything you need to know about building, modifying and power tuning cylinder heads.