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 Air-Gap manifolds, from idle to 5,500 rpm up to 1,500 to 6,500 rpm.
Notes: Includes standard oil fill , as well as early air conditioning support bracket accessory bosses.