He had 3 wins in 1970 for Petty Enterprises in the No. 40 Plymouth Superbird with Maurice Petty as his crew-chief. He won the 1970 Daytona 500 and both races at Talladega Superspeedway. Hamilton won his Twin 125 mile qualifying race for the 1971 Daytona 500 driving Cotton Owens' No. 6 Plymouth, finishing the season with one pole and 11 top five finishes. He retired from full-time NASCAR racing after 1973 because of complications from a neck injury in a 1969 Grand American race.