Xperimental Breeding

Twin superchargers power this unique AMX

Words by Cam Benty;  Photos by Shawn Brereton

For those folks who still remember the American Motors Corporation, it is probably for having produced the Jeep, one of the most profitable models in the history of American-made vehicles. While AMC is long gone, in the late 1960s, a group of rogue corporate executives (visions of Don Draper from the Mad Men TV series come to mind) looked to cash in on the exploding market for hot performance muscle cars. This was a huge gamble for AMC, which at the time was best known for safe and economical passenger vehicles — the stuff Don Draper would never have driven.

The success of the first generation Mustang in 1965 was clearly recognized by the corporate heads who put pen to paper (no CAD rendering machines back then, remember) and developed a pair of prototype concept cars, the fiberglass two-seat AMX and a four-seater AMX II. Crowd response was amazing, and the American Motors eXperimental “AMX” was born.

The first production AMX arrived in 1968, powered by three different V-8 engines ranging from 290 to 390c.i. and backed with either a four- or three-speed automatic transmission. To further capture Camaro and Mustang buyers, the AMX features a host of key performance features, including performance wheels, traction lock rear end, and fat, raised white letter tires.

While the rear seating of the Camaro, Mustang, and other pony cars of the time were of questionable use, the 2+2 theme body style and 108-inch wheelbase was consistent with this grouping of vehicles. The 1968 AMX broke from the pack, available only as a two-seater vehicle — the first such production vehicle since the 1955-57 Ford Thunderbird. In effect, the AMX was more of a competitor for the Chevrolet Corvette. Surprising? Bet you didn’t know the AMX featured a wheelbase of 97 inches, one inch shorter than the 1963-82 Corvette, and a full five inches shorter than the ’68 Camaro and Mustang.

AMX Upgrade

Justin Weirich from Wright City, Missouri, was not originally a big AMX fan, but clearly grew to be one, as the cool ’69 AMX pictured here will attest. In fact, Weirich was more of a Jeep fan, his classic CJ7 powered by a hand-built 401c.i. AMC engine. While his Jeep was cool, he eventually sold it to his father, but kept the 401 with plans to drop the big V-8 into an AMC CJ8 Scrambler. As projects go, he lost interest in the Scrambler, traded it for another vehicle, and the 401 continued to spend time stored in his garage.

The cool nature of the AMX was not foreign to Weirich his wife’s uncle and his cousin both drove these unique American Motors products. But, it was after he spent some time driving one that he was hooked. A quick search of the internet revealed what seemed to be a really nice candidate. As is more often than not the case, the seller far overstated the condition, and a long trip from St. Louis area to Bowling Green, Kentucky, resulted in nothing useful.

Within a day of returning home, another AMX was discovered very close to his home. This trip was much more fruitful, and the new AMX was soon fitted with Weirich’s 401c.i. engine. The 90-percent rust-free AMX was already set up with the factory four-speed manual transmission — another plus to the locally purchased machine.

Not New to the Club

While the AMX was a first for Weirich, building seriously fast street and race cars was not a new thing. An aerospace tooling fabricator by trade, he found car building, by comparison, was not brain surgery. If diversity is a good thing, then Weirich’s diverse line up of cool cars is the ultimate. His portfolio of builds includes a Q-Code 428 Mustang (a convertible with fastback quarter panels hung on it to give it a better shape), a ’68 Camaro with LS3 power, and a ’51 6.0 LS-powered Willys pickup truck — just to hit the highlights.

In addition to the past builds, Weirich is currently building a ’65 Mustang fastback with late model GT500 Shelby power and “everything billet offered by the Ringbrothers.” (Side note:  – Weirich was all set to come and work for the Rings a few years back, but the birth of a child changed his mind and he decided to stay in the St. Louis area. Regardless, Weirich and the Rings remain good friends, and the option to head north to work for the famous brothers is still on the table.)

AMX with a Twist

With AMX in hand, Weirich set about building his unique vision for the car. In went the 401c.i. engine topped with one of the 50 factory reproduction Cross-Ram intake manifolds built by Edelbrock. Of particular note are the individual Mallory coil packs that allow for efficient firing of the spark plugs. Twin FAST EFI throttle bodies and a FAST XFI Sportsman ECU keep fuel management in check, while stainless long tube headers and Flowmaster 40 series mufflers handle the exhaust duties.

Not long after the AMX first fired, Weirich made a trip to the Goodguys Show in Columbus and spotted the TorqStorm display booth, intrigued by the unusual supercharger design. A tech walk through of the product at the booth convinced him of the supercharger’s merits, but he was concerned whether they had a fitment for his rare 401c.i. engine. To cut to the chase, they did not – but they do now.

Using his 401c.i. engine as a template, TorqStorm now offers such a package. Today, Weirich’s AMX sports a pair of superchargers, which blow through the FAST throttle bodies and crank out a ton of power, while making for a most unusual underhood configuration.

The drivetrain features a Tremec close ratio six-speed transmission, which feeds power to the 8.8-inch Ford rear end fitted with a limited slip and 3.73:1 gearing. The front suspension is bolstered with a Control Freak Tubular Front K Member with double-adjusted Viking coilover shocks.  In the rear is a Control Freak triangulated four-link with Panhard Bar. Viking shocks stand at the ready here, as well.

Up front, Wilwood six-piston Ultralight Race version calipers provide maximum stopping power, followed in the rear by Mercury Mountaineer single-piston calipers.  BF Goodrich KWS NT 255/35ZR18 tires wrapped around TSW Nurburgring wheels provide excellent traction.  In the rear, 295/35R18 tires fit well due to the addition of quarter-tubs that provide adequate tire clearance.

Draped in PPG Ford black paint — applied by Weirich and his father — and accented with Dodge Metallic Red stripes under satin clear topcoat, this AMX is truly one of a kind. Inside, Corbeau Baja RS reclining suspension seats and door panels by Legendary Interiors surround the Lecarra LSW Mark 9 steering wheel and T56 MGW short-throw shifter.

Don Draper would be proud.

About Cam Benty - PPN Editor

Cam Benty’s name is instantly recognizable to those that have been around the automotive aftermarket over the last 25 years. He has built a stellar reputation as a well-rounded automotive journalist while holding positions with Popular Hot Rodding, Car Craft, National Dragster and Motor Trend.