100-percent CNC-ported runners optimize volume atomization & velocity. Increased clamping capacity greatly improves head gasket retention in high horsepower & boosted applications.; Edelbrock products offer improved performance and aesthetics for a broad array of vehicles and engines. 'Proven performance' is the philosophy by which Edelbrock was founded and it continues to this day with the highest standards for performance and quality. Edelbrock core products are engineered manufactured and tested in the USA to ensure the best quality possible. This is further backed by some of the best warranties in the industry and a highly qualified technical support staff.; Edelbrock products offer improved performance and aesthetics for a broad array of vehicles and engines. 'Proven performance' is the philosophy by which Edelbrock was founded and it continues to this day with the highest standards for performance and quality. Edelbrock core products are engineered manufactured and tested in the USA to ensure the best quality possible. This is further backed by some of the best warranties in the industry and a highly qualified technical support staff.; Can be used in small & large cubic inch hardcore street applications. Sold Bare Fully Machined with Valve job; 6-bolt head design is compatible w/ the advanced EDELBROCK LS Race GM LSX Blocks or OEM 4-bolt blocks; The heads also utilize the popular LS 6-bolt head design making them compatible with both the EDELBROCK LS Race Block and GM LSX Blocks.; Increased clamping capacity greatly improves head gasket retention in high horsepower and boosted applications; The raised runner and rolled valve angle increase overall flow capability while an improved water jacket design improves thermal conductivity.; 400" raised rail works w/ aftermarket rockers; .100" raised exhaust port allows use of stock & aftermarket manifolds; .750" thick deck surface increases integrity; Reinforced solid rocker rail increases rigidity & stability; 355T6 aluminum withstands race conditions