Threaded inserts in the rocker studs and exhaust manifold bolt holes for superior strength and durability.; 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.; Stock valve cover location & bolt pattern; Accepts distributor ignition or coil rail ignition; .750" deck thickness; CNC combustion chamber 59 ± 1cc (57 ± 1cc stock); 10 degree valve angle (stock); 3.875" bore (stock); Stock head bolt pattern; 1991-1998 intake & exhaust manifold bolt pattern and port locations; Stock pushrod length; Stock valve-train geometry; Larger diameter reinforced rocker bosses