He qualified in the pole position for the July 27 1941 race at the Daytona Beach Road Course beside Roy Hall. Flock took the early lead, before Flock and Hall got together in the south turn. Flock rolled and landed upside down in bushes. The seatbelt broke during the rolling, and Flock was tossed around. He was rushed by ambulance to the hospital. Fonty suffered a crushed chest, broken pelvis, head and back injuries, and severe shock.
His brother convinced car owner Ed Schenck to put Flock in his car at the first race at the North Wilkesboro Speedway on May 5 1947. Flock won the pole and his heat race. He won the 30 lap feature after not racing in 4 1/2 years. He took over his brother Bob's ride later in the season after Bob broke his back. He won seven of 47 races that season, and beat Ed Samples and Red Byron to win the National Championship Stock Car Circuit championship.
He won eleven features and won the NASCAR National Modified championship in 1949. He raced in 6 of 8 Strictly Stock (later Grand National, now Sprint Cup events, and finished fifth in the points.
He raced his first full-time season in the Grand National series in 1951. He had 8 wins, 22 Top-10s, and 13 poles to finish second in the points.
He had two wins, 17 Top-10s, and 7 poles in 1952. He finished fourth in the points.
He held over a one minute lead at the 1953 Daytona Beach Road Course race, but ran out of gas taking the white flag at the start of the final lap. Flock’s teammate pushed his car into the pits. Bill Blair passed to win the race in a 1953 Oldsmobile. Flock finished second by 26 seconds. He had 4 wins, 17 Top-10 finishes, and 3 poles to finish fourth in the final points.
He opened an insurance agency in 1954, and he raced part-time after that.
He raced 31 of 45 events in 1955. He had 3 wins, 14 Top-10s, and 6 poles. He finished eleventh in the points.
He had his final win in 1956 at the Charlotte Speedway (not Lowe's Motor Speedway).
In 1957 he raced at the Daytona Beach Road Course. Herb Thomas was injured while practicing for the Southern 500 at the Darlington Raceway, so Flock got his ride. The car was in bad shape, and a tire blew on the sixth lap. Flock walked away unhurt, but he decided to walk away for good.