BBC 427

A special 427 cubic inches (7.00 L) version of the 409 engine was used in the 1963 Chevrolet Impala Sport Coupe ordered under Chevrolet Regular Production Option (RPO) Z11. This was a special package created for drag racers, including aluminum engine and body parts and a cowl-induction air intake system, along with the 427 engine. The aluminum body parts were fabricated in Flint, MI at the facility now known as GM Flint Metal Center. Unlike the later second generation 427, it was based on the W-series 409 engine, but with a longer 3.65 in (93 mm) stroke. A high-rise two piece aluminum intake manifold and dual Carter AFB carbs fed a 13.5:1 compression ratio to produce an under-rated 430 hp (320 kW) and 435 lb•ft (590 N•m). 50 RPO Z11 cars were produced at the Flint plant. GM Documents exist that show 50 Z11 engines were built at the GM Tonawanda engine plant for auto production, and 20 partial engines were made for replacement/over the counter use. No evidence from GM has been found that show 57 cars were built.