In 1963, Chrysler engineers developed the legendary 426 Hemi engine by combining a Hemi head with a modified raised-block 426 wedge, aiming to create a competitive NASCAR powerplant. The extensive racing experience influenced its design, and to meet NASCAR requirements, it had to be available in a street version.
The Street Hemi incorporated performance components from the race version, such as the crankshaft, connecting rods, and cross-bolted main bearing caps. The hydraulic lifters and lower rate springs of the milder camshaft were used to limit RPM to the management-imposed 425 limit.
Paired with dual Carter AFB carburetors, the Street Hemi became an awe-inspiring powerhouse that defined the era. Over time, it has earned the status of the most sought-after and valuable engine of the Muscle Car era.
In 1970, the new ‘Cuda model was specifically designed to accommodate the legendary 426 cubic inch Hemi engine. With a price tag 70 percent higher than Plymouth’s largest powertrain, the 440-cid 390-hp Six Barrel, the Hemi was targeted at serious racers. Additionally, the Hemi-powered ‘Cudas were only produced for two model years, 1970 and 1971, adding to their rarity and desirability.
Source: Bonhams