The new design incorporated an integral roof spoiler and sculpted fender bulges. The new body departed from the gentle, tucked-in look of the original.
The media noted the revised front fenders (originally designed to accommodate oversized racing tires) that "bulge up as well as out on this personal sporty car, borrowing lines from the much more expensive Corvette." The new design also featured an "intricate injection moulded grille."
The car's dashboard was asymmetrical, with "functional instrument gauges that wrap around you with cockpit efficiency". This driver-oriented design contrasted with the symmetrical interior of the economy-focused 1966 Hornet (Cavalier) prototype.
AMC offered a choice of engines and transmissions. Engines included a 232 cu in (3.8 L) I6 and a four-barrel 401 cu in (6.6 L) AMC V8 with high compression ratio, forged steel crankshaft and connecting rods engineered to withstand 8000 rpm. The BorgWarner T-10 four-speed manual transmission came with a Hurst floor shifter.
The 1970 Javelins featured a new front end design with a wide "twin-venturi" front grille incorporating the headlamps and a longer hood. It also had a new rear end with full-width taillamps and a single center mounted backup light. This was a one-year only design. Side marker lights were now shared with several other AMC models. The exterior rear view mirror featured a new "aero" design and in some cases matched the car's body color. The three "Big Bad" exterior paints continued to be optional on the 1970 Javelins, but they now came with regular chrome bumpers. Underneath the restyle was a new front suspension featuring ball joints, upper and lower control arms, coil springs, and shock absorbers above the upper control arms, as well as trailing struts on the lower control arms.
The 1970 AMC Javelins also introduced Corning's new safety glass, which was thinner and lighter than standard laminated windshields. This special glass featured a chemically hardened outer layer. It was produced in Blacksburg, Virginia in a refitted plant that included tempering, ion exchange, and "fusion process" in new furnaces that Corning had developed in order to be able to supply to the big automakers.
The engine lineup for 1970 was changed with the introduction of two new V8 engines: a base 304 cu in (5.0 L) and an optional 360 cu in (5.9 L) to replace the 290 and the 343 versions. The top optional 390 cu in (6.4 L) continued, but it was upgraded with new cylinder heads featuring 51 cc combustion chambers, increasing power to 325 hp (242 kW). The code remained "X" for the engine on the vehicle identification number (VIN). Also new was the “power blister” hood, featuring two large openings as part of a functional cold ram-air induction system; this was included with the "Go Package" option.
Many buyers selected the "Go Package", available with the 360 and 390 four-barrel V8 engines. This package as in prior years included front disc brakes, a dual exhaust system, heavy-duty suspension with anti-sway bar, improved cooling, 3.54 rear axle ratio, and wide Goodyear white-lettered performance tires on styled road wheels.
The interior for 1970 was also a one-year design featuring a broad dashboard (wood grained on SST models), new center console, revised interior door panel trim, and tall "clamshell" bucket seats with integral headrests available in vinyl, corduroy, or optional leather upholstery. A new two-spoke steering wheel was available with a "Rim Blow" horn.
A comparison road test of four 1970 pony cars by Popular Science described the Javelin's interior as the roomiest with good visibility except for a small blind spot in the right rear quarter and the hood scoop, while also offering the biggest trunk with 10.2 cubic feet (289 l) of room. It was a close second to the Camaro in terms of ride comfort, while the 360 cu in (5.9 L) engine offered "terrific torque." The 4-speed manual Javelin was the quickest of the cars tested, reaching 0 to 60 miles per hour (97 km/h) in 6.8 seconds.