Dale Earnhardt Jr. blinked back tears as the moment socked him at Daytona International Speedway — a track bursting with triumph and tragedy for his family — that he was, with a country star and a NASCAR champ in tow, back in the Daytona 500. “I can’t believe that we get to race on Sunday,” Earnhardt said. Long NASCAR’s most popular driver as he built a Hall of Fame racing career in the intimidating shadow of his father, Earnhardt celebrated Thursday night at the track where he won two Daytona 500s and suffered the loss his father on the last lap in the 2001 race.