The Australian Repco V8 F1 engine being based on Buick 215 block is technically a common misconception, as the Rover/Buick V8 had only 5 cylinderhead studs around each cylinder unit and that cannot accommodate the 6 stud Repco RB620 heads. The Repco V8 was based on Oldsmobile 215 block of the same era, which was very similar in appearance, size and material, but used 6 cylinderhead studs per cylinder. The subtle difference in block design/head clamping originated in Oldsmobile's intention to produce the higher power, turbo-charged Jetfire version of the small/light V8, however, the public/press tended not to be aware of the internal difference.