In 1970, Ford aimed to gain an edge in the Trans-Am racing series with a rule-bending carburetor design. The “Cross Boss” was an innovative attempt to boost performance while staying within the regulations—until it didn’t. This era of racing was defined by intense competition, with manufacturers like Ford, GM, Mopar, and AMC pushing the limits of what was allowed to gain an advantage. The track action was only part of the story; many races were effectively won off the track through meticulous preparation and innovative engineering.
The Race to Innovate
Racing often comes down to preparation and finding advantages within the rules. Ford’s engineers focused on the carburetor, a critical component for engine performance. The Trans-Am series had banned complex dual-four-barrel carburetors to reduce costs, but Ford saw an opportunity. This ban was specifically aimed at lowering expenses for privateer entrants, ensuring a more level playing field. However, Ford’s engineers interpreted the rules creatively, designing a carburetor that technically complied but offered significant performance benefits.
They designed a cast-aluminum intake and a unique carburetor. Instead of the typical arrangement of four barrels in two rows, Ford lined up all four venturis in a single row. This design aimed to improve airflow and fuel distribution, mimicking the benefits of individual carburetors or even multi-port fuel injection. By placing the carburetor in the center of the intake manifold, Ford engineers addressed the issue of sharp bends that air and fuel had to handle to reach the outer cylinders, particularly cylinders #1, 4, 5, and 8. This innovation reduced turbulence and ensured more even fuel distribution, enhancing engine performance.
A Technical Triumph—Briefly
The Cross Boss transformed Ford’s 302 V8 engine, trading low-end power for high-revving performance. The design also featured a removable plenum cover, allowing for easier modifications and venturi sleeve swaps. This modularity was a turning point for race teams, enabling quick adjustments to optimize performance for different track conditions. Two versions were created: one for Trans-Am and NASCAR, rated at 850 or 875 CFM, and a 1,400 CFM version for drag racing. However, competitors from GM, Mopar, and AMC argued that the design violated the spirit of the rules, leading to its ban before it could be raced.
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Ford reportedly built around 500 to 700 of the “in-line four” Autolite carbs and a mere 100 of the intake manifolds. Despite the ban, Ford won the 1970 Trans-Am Championship with a traditional setup. This victory showed Ford’s engineering prowess, even without the Cross Boss, and cemented their reputation as a dominant force in motorsports.
The Cross Boss’s Impact and Legacy
The Cross Boss’s design aimed to maximize airflow and fuel distribution, addressing the limitations of traditional four-barrel carburetors. By lining up the venturis in a single row, Ford engineers created a setup that mimicked the benefits of individual carburetors or multi-port fuel injection, all while technically adhering to the rules. This approach exemplified the spirit of innovation that defines racing, where engineers constantly seek ways to interpret regulations to their advantage.
Collectibility and Enduring Appeal
Despite its short-lived racing career, the Cross Boss has become a highly sought-after collectible. With only 500 to 700 carburetors and 100 intake manifolds produced, these components are rare and valuable. One photographer who received a unit noted the high prices they command, with some selling for over $5,000. The scarcity of these parts, combined with their historical significance, has made them prized possessions among automotive enthusiasts and collectors.