(426 and 572 Hemi blocks)
After production of the street Hemi® stopped in 1971, enthusiasts were faced with a limited supply of Hemi parts. Direct Connection (now Mopar Performance) and aftermarket vendors helped, but blocks and heads became rarer as time went on. The musclecar collecting craze sent Hemi prices through the roof, buyers of used parts had to be wary. Racers also had to deal with the possibility of violating NHRA specs as blocks wore and numerous valve jobs sunk the heads deeper into the combustion chambers.
Starting in late 1992, Mopar Performance began making new 426 Hemi blocks, moving on to heads, pistons, and other parts, making it possible to build a new 426 Hemi. The new block had the same outward appearance as the original (except for a new casting number), with a thicker deck for better stiffness and gasket sealing; the improved rigidity brought around 25 extra horsepower. Mopar Performance also made a version with B/RB engine mounts, so a Hemi could be dropped into a big block car without a Hemi K-member. The heads had hardened valve seats to allow unleaded fuel; in later years, Mopar added a single 4-bbl manifold, and a magnesium supercharger manifold for top fuel racing.
|A Short List of Key 1990s 426 Hemi Part Numbers:|