The Allard J2 Engine and the 1951 Allard J2-X
Now let's discuss the Allard J2 engine and the 1951 Allard J2-X.
In addition to improving the chassis, Allard knew he had to do something to dramatically increase the power. The flathead Ford V-8 was by then 18 years old and -- in spite of the enormous amount of available speed equipment -- was no longer suitable to power a serious competition car. By coincidence, an overhead-valve conversion for the flathead Ford/Mercury V-8 was being created in New York City by Zorro Arkus-Duntov, later of Corvette fame, in a loft he shared with Luigi Chinetti, who would soon become the Ferrari distributor for the U.S.
Duntov's design, which he called the Ardun conversion, was a pushrod and rocker-arm system working off the Ford camshaft in its stock location. The push-rods for the intake valves utilized short rocker arms located toward the inside of the engine's "V," while the exhaust valves were worked by long rocker arms (one of the few weak spots in the design) toward the outside of the engine. The result was inclined valves, 90 degrees apart, in hemispherical combustion chambers. If that sounds like the Chrysler Hemi V-8, you're right, but this was in 1950 -- before the Hemi's 1951 model year debut.
No one in England, it seems, could make the Ardun engine perform reliably or well, so Allard wrote to Duntov to complain, with the result that Zora went to Clapham to take charge of the engine's development. Even so, Allard ultimately dropped the Ardun as an engine option after selling around 75 of them.
In 1950, Allard and American Tom Cole shared an Allard-Cadillac J2, driving it to third place overall in the prestigious Le Mans 24-hour race, behind two Grand Prix Talbots fitted with two-seat sports car bodies. This victory was a primary reason for the survival of both the model, and of Allard Motor Car Company, although a new version, the J2-X was due to be announced in 1951.
The "X" at the end of the name meant "extended." But it wasn't the wheelbase that had changed-it remained at 100 inches as on the J2. Rather, the alterations were found mainly in the chassis components. For example, the engine was moved forward 7.5 inches because legroom had been a sore point with J2 buyers. This helped cockpit space, but caused a problem of relocating the front suspension mounts. The mounting structure for the inner ends of the split front axle had to be moved in front of the axle, which necessitated a six-inch frame extension up front. In back, enlarging the fuel tank in the rear body section made it necessary to mount the spare tire on the side of the body rather than in the lower section at the rear of the body. Track, however, remained the same as on the J2: 56 inches front, 52 inches rear.
Somehow, all this shifting of components made the J2-X handle better than the 12, so the combination of handling plus improved driver comfort made the J2-X a more frequent race winner.
Meanwhile, the lack of a four-speed transmission was still a bother to many owners, so Allard tried to compensate for this by switching from a 3.54:1 to 3.27:1 axle ratio (both standard Ford gearsets). This was unsuccessful, however, so Allard engineers next attempted to make a suitable four-speed out of a Thames truck transmission produced by Ford of England. Four of these gearboxes were made in the shop for the streamlined J2-X team cars in early 1952, but these units were plagued by a major design flaw. Though they obtained a close ratio between first and second, and between third and fourth, it proved impossible to close the overly wide gap between second and third because the necessary gear size couldn't be squeezed into the available space. Another problem was that the truck gearbox was made of cast iron, and therefore heavier than desirable.
To find out more about the 1949-1954 Allard continue on to the next page.
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