SBC Modified Long Tube Header 1-3/4 Spread Port

The SCHOENFELD SBC Modified Long Tube Header 1-3/4 Spread Port (model 1186SP) is a purpose-built exhaust manifold designed for small block Chevy IMCA Modified race engines. This pair of headers features 1.75-inch primary tubes that flow into a 3.5-inch collector, engineered to optimize scavenging efficiency and peak power output in the Modified class where engine displacement and induction modifications are tightly controlled. Built from steel with black paint finish, these headers arrive complete with gaskets and mounting hardware.

The spread port design distinguishes this header by routing primary tubes outward from the cylinder head, reducing thermal load on adjacent engine components and improving underhood heat distribution—a critical consideration in Modified racing where engine bay temperatures directly impact fuel stability and component longevity. The 1-3/4-inch primary tube diameter targets the exhaust velocity sweet spot for naturally aspirated small block Chevy engines in the 350–383 cubic inch range, balancing back pressure against flow capacity. The larger 3.5-inch collector consolidates exhaust gases efficiently before the transition to secondary piping, supporting consistent scavenging across the RPM range typical of circle track competition.

These headers are engineered for IMCA Modified class competitors who build small block Chevy engines under strict rules-book specifications. The combination of tube diameter, collector size, and spread port configuration reflects years of race engineering optimization for this specific class. Weighing 31.2 pounds per pair, they integrate into standard small block Chevy engine bays without significant modification. Serious oval track racers building rule-compliant powerplants will recognize the SBC Modified Long Tube Header as a proven OEM-quality component that delivers measurable performance gains in qualifying and race conditions.