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.