In the late 1960s Pontiac offered several powerful V8 engines that consumed large volumes of air through its Ram Air induction system. Later versions featured round exhaust ports for improved flow over the earlier D-shaped designs. Engineers wanted to enlarge the intake ports as well to boost airflow and output but the pushrods for the intake valves blocked the way. The division therefore looked elsewhere for a solution.

Pontiac learned of a Ford cylinder head layout that moved the pushrods out of the intake path and decided to adopt the idea. The resulting Ram Air V engine used the borrowed concept yet still fell short of the performance targets. Low-speed torque suffered and the program ended before any production cars received the new V8.

Pontiac needed more airflow after the Ram Air IV

The Ram Air name first appeared in 1965 as a dealer-installed option for the GTO's 389 cubic inch V8. It used a pan and gasket to draw cool outside air through hood scoops directly into the carburetors. Three further Ram Air iterations followed until airflow limits appeared after the Ram Air IV. Engineers still hoped to enlarge the intake ports on upcoming high output and Super Duty engines but the pushrods remained an obstacle.

George DeLorean who had a drag racing agreement with Ford noticed that a Ford engine with a similar layout produced more power. He obtained one of Ford's Tunnel Port cylinder heads for study and shared it with Pontiac engineers including Steve Malone Mac McKellar Tom Nell and Bill Klinger.

Ford's pushrod-through-port solution became Pontiac's Tall Port head

Ford had simply routed the pushrods straight through the intake ports allowing them to remain large and round. Pontiac engineers photographed measured and molded the head before returning it. Their own version received the internal name Tall Port head.

The new ports delivered greater airflow than any prior Ram Air engine. At the same time the extra volume created a problem. With only 400 cubic inches of displacement some air remained trapped in the ports reducing low rpm output. The effect was worse on the 303 cubic inch version. The design worked only on very large displacement engines at high rpm. Before Pontiac could develop suitable larger engines the program was cancelled.

A few hundred developmental 303 and 400 cubic inch Ram Air V engines were built but none reached production vehicles. The 400 cubic inch version had been intended as Pontiac's strongest classic era powerplant yet it remained a developmental exercise and never entered the market.