ON A LATE SUMMER’S day in 1978, 13-year-old James Cox and his father, Ed, drove 90 miles from their home in Larchmont, New York, to the Lime Rock Park racetrack in rural Connecticut.

With his range-finder camera, a recent gift from his father, James sliced through the crowds, carefully avoiding officials and snapping photos of cars barreling around the track and drivers prowling the pits. He spotted a driver in a blue racing suit, sweat-drenched but relaxed in a roped-off area. Earlier, James had heard the track announcer...