Edelbrock part #7505 RPM Air-Gap Dual-Quad FE #7505 intake manifold is designed for 1960-later high-performance's street 390-406-410-427-428 c.i.d. Ford FE engines with low/medium rise or Edelbrock Performer RPM FE heads #60059 or #60069. The manifold carb pad is setup to fit Edelbrock carburetors only, will not work with other square flange carburetors. In Dyno tests on a 390 with Performer RPM heads #60069, Performer RPM camshaft #7106 Thunder Series AVS #1803 and #1804 carburetors, it made 452 hp and 428 ft-lbs. torque. Will not fit 427 Ford Hi-Riser and Tunnel Port engines. Has machined boss for a breather flange at rear.