Importing American engines just to ship them back across the Atlantic proved problematic, so U.S.-bound Allards were soon shipped engineless and fitted out in the States variously with newer overhead valve engines by Cadillac, Chrysler, Buick, and Oldsmobile. In that form, the J2 proved a highly competitive international race car for 1950, most frequently powered by Cadillac engines. Domestic versions for England came equipped with Ford or Mercury flatheads. Zora Duntov worked for Allard from 1950 to 1952 and raced for the factory Allard team at Le Mans in 1952 and 1953.