1969 Ford Mustang
To compete with the Mopar HEMI engine in NASCAR, Ford launched the BOSS 429 V8 in 1969. It was built as a limited production Mustang Fastback to meet the required homologation of 500 units. The ’69 BOSS became the ultimate Mustang after the ‘clydesdale’ body was used for the 1970 version.
Ford prepared the 429 for inclusion into NASCAR’s Grand National Division. They modified a version Ford’s big block V8 design known as the ‘Ford 385 engine’ and changed the stroke from 3.85 inches to 3.59. Built as a full-on race engine the exhaust ports were so large, it was nicknamed the ‘Shotgun engine’.
Power was legally rated to 375 horsepower (280 kW) although 500 horsepower (370 kW) was possible. To meet emissions regulations, a mild cam was fitted along with a smog pump and small carburetor. With a few modifications up to 600 bhp was common.