The arrival in F2 of BMW and Renault left Ford reluctant to increase its involvement, so Hart chose to develop his own F2 engine - the 420R - which was first raced in a Chevron sportscar in 1976.
A chegada á F2 de BMW e Renault deixou a Ford renuente a aumentar a súa participación, polo que Hart optou por desenvolver o seu propio motor de F2, o 420R, que foi o primeiro en competir con Chevron en 1976.