Product details:
The open air space from the Air-Gap design separates the runners from the heat of the lifter-valley cover. So, the air/fuel mixture stays cooler all the way to the heads, which produces a denser charge for more power. Runners are tuned to move the power band 1,000 rpm higher than Performer Air-Gap manifolds, from idle-5,500 rpm up to 1,500-6,500 rpm. Edelbrock. 7521 fits these applications: FORD 5.0L/302 Ford small block Windsor, FORD 4.7L/289 Ford small block Windsor, FORD 4.3L/260 Ford small block Windsor.