Although all manufacturers were familiar with multi-valve engines and hemispherical combustion chambers, adding more valves per cylinder, or designing the complex valvetrain needed for a hemispherical chamber were expensive ways of improving the high–revolutions per minute (rpm) breathing of production vehicles. By canting the angle of the NASCAR-mandated two valves per cylinder, significantly larger valves could be used. The Chrysler 426 Hemi and all Chrysler RBs had oversquare bore and strokes. Specifically, the 426 Hemi and 426 Wedge had a bore x stroke of .