What Makes A Hemi Different From A Max Wedge?

Let's dress it's May 1962 and you're a diehard Chrysler loyalist who loves resistance racing. You could hunt for a utilized 392 Hemi, but bully luck keeping nan bottommost extremity from grenading aft slapping connected an 8-71 blower and moving nitromethane. Unfortunately, nan 417 Donovan block with its 72-stud main base girdle is 9 years distant from debuting, truthful that's not going to help. However, you could plunk down a stack of rate connected a caller "Maximum Performance" wedge-headed 413-cubic-inch beast, called Max Wedge for short. You heard that Chrysler's 413 pushed the 300F GT to a apical velocity of almost 145 mph connected Daytona Beach successful 1960, and now nan engine's being prepped for quarter-mile runs. 

The 413 Max Wedge was a existent monster, making up to 420 hp, much than 1 horsepower per cubic inch. In 1963, nan Max Wedge grew to 426 cubic inches, offering up to 425 street-unfriendly horsepower, but it wasn't to beryllium nan apical Mopar offering for long. In 1964, nan Hemi came back. Boy, Chrysler conscionable can't discontinue nan hemispherical combustion chamber. It ever weighs nan Hemi's pros and cons, and ends up deciding that nan powerfulness is worthy nan downsides. 

In a Hemi, nan combustion chambers are, arsenic nan sanction implies, astir half-spheres, which allows for monolithic valves, businesslike combustion, and fantabulous airflow. In a Max Wedge, nan valves are correct adjacent to each other, and tally azygous record successful statement pinch nan cylinder banks. While this makes for a lighter, cheaper valve train and smaller wide dimensions, it limits nan size of nan valves and horsepower potential. Still, a 413 Max Wedge-powered Plymouth Savoy nicknamed nan Melrose Missile was nan first mill banal car to tally successful nan 11s done nan quarter.

Before exploring nan minutiae of Chrysler's nomenclature and nan specifics of nan Max Wedge and Hemi engines successful nan early '60s, let's further analyse method differences. Inspect this picture, noting nan variety successful piston and valve train design. The apical half shows Hemi components, including nan splayed-out rocker arms basal for actuating valves group astatine melodramatic angles. The pushrods travel up betwixt nan rocker shafts, and some intake and exhaust valves each get their own shaft. Also announcement nan domed piston, which gives a bully thought arsenic to wherever nan valves beryllium successful nan head. The bottommost half of nan image shows nan acold simpler wedge-head valve train. Rockers run connected a azygous rocker shaft and pushrods are much aliases little parallel. The piston is, for each intents and purposes, flat.

As for branding, successful 1962, astatine Dodge, nan motor was called nan Ramcharger 413, and astatine Plymouth, it was nan Super Stock 413. Base compression was 11:1 and bully for 410 hp, but an optional head-cracking 13.5:1 compression type made 420 hp. While some modern engines request today's premium gas, a high-compression Max Wedge requires 104-octane Sunoco. Both engines featured nan coolest-looking "crossram" intake pinch dual four-barrel carbs, forged internals, a high-lift cam, and a baffled lipid pan. 

In 1963, displacement accrued to create nan Ramcharger 426 and Super Stock 426. Horsepower bumped up to 415 for 11:1 engines and 425 for 13.5:1 engines. In May 1963, Chrysler made flimsy improvements and dubbed nan engines "Ramcharger 426A" and "426 Super Stock II." After immoderate further refinement successful 1964, nan engines became nan "426 Super Stock III" and nan "Ramcharger 426 III." These numbers are wherever nan "Stage II" and Stage III" nicknames travel from.

Unfortunately for nan Max Wedge, 1964 was nan twelvemonth that Chrysler brought backmost nan Hemi. The "Race Hemi" displaced 426 cubic inches and had 12.5:1 compression. It moreover gained aluminum heads successful 1965. Thanks to its success, nan "Street Hemi" was born. Though it had a little compression ratio of 10.25:1, a milder cam, and cast-iron heads only, it still had 425 hp and crushing performance. Meanwhile, nan wedge caput didn't die, it conscionable became 2nd banana. Chrysler punched it retired to 440 cubic inches and utilized it successful everything from nan comfy Chrysler 300 onshore yacht to nan sharp, Mustang/Camaro-battling Dodge Challenger and Plymouth 'Cuda, wherever it made up to 390 hp. 

In a horsepower race, manufacturers will do crazy things, and nan 1960s saw immoderate stupendous experimentation. Ford's single-overhead-cam 427 generated much than 600 hp and was sold done velocity shops. Chevrolet added substance injection to Corvettes and produced aluminum blocks for nan uncommon ZL1 427. Pontiac's Ram Air V heads had intake ports truthful ample that nan only spot for nan pushrods was, well, straight done nan port. Oldsmobile moreover developed a 32-valve 455 that, for illustration an LB7 Duramax Diesel, still utilized an overhead valve arrangement. Chrysler moreover tried pushing motor tech guardant pinch a monolithic prototype double-overhead-cam pentroof 426, which intends that Dodge did effort to ditch pushrod V8s astatine 1 point. 

And American Motors Corp. was, uh, there. Look, nan 390 and 401 are awesome engines, but different than nan 1957 fuel-injected 327 that ne'er really made it into nan Rambler Rebel, nan company's engines were beautiful conventional. If you want crazy AMC, cheque retired a Randall Gremlin 401-XR.