Jim Smart
September 19, 2006
Photos By: Tom Rounds

When you consider the value of Shelby Mustangs these days, it's hard to believe so many have succumbed to the whims and impulses of hot-footed, mechanized maniacs through the years. We've all heard the horror stories of fast Shelbys wrapped around utility poles, stuffed in trees, flipped, rolled, and chopped up to go racing. We're surprised there isn't some legendary song dedicated to Shelby Mustangs, much as there has been GTOs, 409s, surfers, and even Cobras. Though it may seem impossible today, Shelbys were once run-of-the-mill, used, high-performance Mustangs that peppered classified-ad sections from coast to coast. At the time, few people understood what these cars were, nor did many care.

Art Nigro is a Shelby enthusiast who got on board in 1974 when the cars were plentiful and cheap. He enjoys a fine appreciation for Shelby Mustangs, fondly remembering what makes them so popular today. They're popular because they have a legacy of race-winning performance and the distinction of rarity. A good many of them are gone. And not every GT350 or GT500 stripe-clad Mustang you see is real. There are a lot of clones, but only a few genuine originals. Shelby Mustangs spark curiosity wherever they go.

When Art found this Raven Black '67 GT350 in 1974, it was worse for wear because it suffered a rough and tumble past. The original 289 High Performance V-8 engine was gone, replaced by a succession of rumpity-rump-rump engines leading up to the Boss 302 mill currently parked between the shock towers. When Art stepped up to buy his Shelby 32 years ago, it was fitted with a 351 Cleveland. Prior to the Cleveland was a stroked Boss 302 engine a previous owner blew up. Somewhat overwhelmed with what he saw, Art decided to chance it, take the Shelby, and run. It cost him $1,500. He has never regretted the decision, and says, "I fell in love with '67 Shelbys at the age of 16 when I got a ride in New England Dragway's resident GT350. I just had to have one."

When Art brought the Shelby home, there was a lot of work to be done. Money being what it was then, not a lot was accomplished on the car until later on. In 1979, Art drove his primered GT350 to a Shelby show on Cape Cod. En route, he and a buddy in a modified '67 Mustang were pulled over by the police. Because Art's Shelby wasn't entirely legal (state inspection and licensing), it looked as if the car would be impounded. What saved Art wasn't wishful thinking or a visit from his guardian angel. It was a member of the local Shelby club who was well connected with the local police department. Art quietly drove his Shelby home-prayers answered.

Sometime later, Art was moving the Shelby to his father's garage when his rare Autolite In-Line four got into trouble. A stuck float flooded the carburetor. Then, the engine backfired, starting a fire. Art watched in horror as the flames licked the fiberglass hood. Fortunately, he wasn't far from a firehouse. Still, it seemed like an eternity before he could get the Shelby close enough to find help. Must have been that guardian angel we spoke of earlier. Art has carried a fire extinguisher in the Shelby ever since.

Art's Shelby has evolved through the years. After the underhood fire, he replaced the hood and front fascia with new ones from Maier Racing. While he was at it, he customized the front end with some 'glass of his own, making the car unique. He deleted the front bumper to give the car a road race demeanor. Paint and GT350 graphics followed later.

Underneath, Art has kept his car much the way Carroll Shelby built it 40 years ago. He has 620 coils in front, five-leafs in back, Koni adjustable shocks fore and aft, staggered Boss 302 style aft for stability, and 16:1 worm and sector steering to help tighten up things. Those are genuine 15x8-inch Minilite color-keyed wheels married to BFGoodrich Radial T/As. Inside, Art left the interior very much alone, keeping the correct Stewart-Warner instruments and Shelby interior intact.

Underhood is where Art took a side track and tried something different. That's a Boss 302 engine with Autolite's In-Line four-barrel carburetor. Ford called it the Cross Boss induction system. Unique in its approach to metering and distributing air and fuel, the Cross Boss was designed for SCCA Trans Am road racing. For all the bells and whistles of this unique design, it didn't set the world on fire in competition. More conventional Holley-carbureted induction systems worked better and were easy to service.

The Boss 302 engine is a born to race V-8. This one has 12:1 compression, a 300-degree duration, 0.585-inch lift mechanical camshaft, a 13-pound flywheel, and that 875-cfm Autolite In-Line four on top. It's radical, and it is surely fast when the butterflies are pinned. According to Art, Ford did just 1,000 Autolite In-Lines and 100 Cross Boss manifolds before production ended.

The Autolite In-Line four-barrel carburetor is undoubtedly the most unusual Ford carburetor ever made. We like the Autolite In-Line four for its unusual nature and rare demeanor. But why did this carburetor happen in the first place, and why wasn't it successful?

The in-line four was developed as a response to SCCA Trans Am's single four-barrel carburetor rule back when the heat was hot and Ford was determined to win. Ford engineers concluded performance could be dramatically improved by changing throttle-bore configuration while remaining within SCCA Trans Am rules. The belief then was, since the rule isn't specific about what kind of four-barrel carburetor can be used as long as it's a four-barrel carburetor, what the heck, let's go for broke-and they did.

Lining up the throttle bores made a difference in performance and looked terrific to boot. The in-line four was an intimidating package because it looked exotic. Heck, it was! It did a much better job on the high end, where Boss 302 engines liked to live, making it worth the investment of time and money to develop.

There were two basic in-line four versions-850 cfm and 1,400 cfm. The 850-cfmversion (D0ZX-9015-A) with 1111/416-inch bores was designed for road racing and NASCAR. There was also a 1,400-cfm version (D0ZX-9015-B) with 211/44-inch throttle bores intended for drag and unlimited-class racing.

"Cross Boss" is actually the name applied not to the carburetor, but the intake manifold it was designed with. This was a two-piece design with Ford part numbers D0ZX-9425-A and D0ZX-9C483-A.

The Autolite In-Line four does not make a good street carburetor unless you intend to cruise at high revs. The Cross Boss/In-Line four combo is a race-only induction system even though some of us have used it on the street. It is not a low-end torque-mindful induction system. The Cross Boss/In-Line four is all about high-end breathing and horsepower well above 5,000 rpm. If you don't care about low- to midrange torque, have a fistfull of dollars burning a hole in your wallet, and want the slickest Ford induction system ever conceived, there's an Autolite In-Line four/Cross Boss combo out there waiting for you.

When we spotted Art's Shelby at the '05 Carlisle All-Ford show, it was one of only two cars at the show of over 2,600 vehicles with an Autolite In-Line and the only inline-powered car to drive to the show. That's because Art has severely modified his in-line to run on the two center barrels and only use the outer two barrels when needed via vacuum secondaries using a custom designed three-piece throttle shaft. He has also resized the venturis to provide good street performance (down to 1.4 inches from the stock 1.6 inches), and he has adapted the emulsion tubes to accept standard Holley jets for easier tuning.