The muscle car era had truly begun to come into its own by 1966. Spurred on by the increased popularity of domestic automotive performance on the nation’s NASCAR tracks and drag strips, a growing acceptance of Formula 1 and sportscar racing (due in no small part to Shelby’s Mustangs), and an overall push in the enthusiast media from modified, home-built rods to OEM equipment, things were getting hot, hot, hot. People wanted performance.
 While it looks cool, mounting that tach on the console made it hard to see. The shifter used was still the Inland version rather than Hurst; this and the linkage were some of the first stuff to head to the junk pile if a driver was serious about racing. |
At the same time, however, the wave was still just moving, not pushing or cresting as it would during the 1968-1970 period. Detroit’s auto builders were still making adjustments to existing packages rather then releasing specifically redesigned models. There was hot equipment in 1966, to be sure. Olds had their dreaded W30/L69 4-4-2 drag package, Pontiac was making waves with the tri-power GTO, Ford was scratching the surface with some very limited 427 Fairlanes and Comets, and Chrysler decided to call Bill France’s bluff by putting their full-tilt race engine into passenger cars.
 Vintage original decals from the NHRA Nationals at Indianapolis have been on the car since the 1960s. None of them showed participation, however. |
The big-port 426 Hemi was never meant to do anything but spin horsepower out at RPM levels above 3000. It was not built with low-end torque in mind; it was a finicky engine that required more than a screwdriver and some luck to keep properly tuned, and it would eat parts (tires if you were brutal on the pedal, camshafts just through normal wear due to the high valve spring pressures). The Hemi had taken the world by storm in 1964 at the Daytona 500, then had revolutionized stock-bodied drag racing when the company boycotted NASCAR following France’s decision to not let any ‘non-production’ engine compete in his sanction in late 1964. At the start of the 1966 model year, the engine became an option to become legal once again, pushed by Bob Rodger, who drafted a memo on January 6, 1965, to make the engine available for street use. Incidentally, this superceded a multi-carb version of the 426 street wedge that was projected for development, according to http://www.allpar.com/mopar/hemi/hemi.html.
But putting the Hemi into a street vehicle was a little more complicated than simply slipping it in. Sure, it fit with only a little trouble due to the cylinder head widths, but special provisions were needed to bring heat into the new intake manifold (pipes from the exhaust system did this). Taking a page out of the early 1960s playbook, engineering selected a high-rise dual plane intake with two inline 625-cfm AFB carbs (one with a choke) rather than then the cross-ram layout used on the previous year’s Super Stock cars. Compression was actually mild at 10.25, and the cam was a solid-lifter unit with .467 intake/.473 exhaust specs, again both compromises for street use.
There was the rest of the driveline to consider as well; this thing was still stout. However, Chrysler had spent much of the early 1960s refining components that would take a thrashing in the race environment. The automatic 727 Torqueflite and A833 four-speed box were up for the task, though the Hemi option meant some additional OEM beefing to the transmissions. The differential for the automatic was the larger pinion 8.75 banjo type, but a 9.75 truck-type unit by Dana Industries was mandated in four-speed applications. Both had SureGrip traction packages, with a 150-mph possible 3.23 gear as the standard ratio.