Designed to improve performance on the street or racetrack, the RPM Air-Gap 351 Cleveland intake manifold features an open space that separates the runners from the hot engine oil resulting in a cooler, denser charge. The Edelbrock Air-Gap design utilizes the same race-winning technology that's been used on Edelbrock's Victor Series competition intakes for many decades. The RPM Air-Gap manifold for 351 Cleveland engines is designed to complement Edelbrock's 351C Performer RPM cylinder heads 350-61609, 350-61629 and also works well with 4V and 2V cast iron Cleveland heads.