In 1953, Welborn drove in 11 NASCAR Grand National events, 3 driving for Julian Petty and 8 races in Goode’s Plymouth. That year he had 2 top 5 finishes and 6 top 10 finishes in his 11 starts.
In 1954, Welborn once again drove mainly for Julian Petty. He finished the year with 1 top 5 and 3 top 10 finishes.
1955 he entered 32 of the years 45 races. Welborn started the season behind the wheel of Julian Petty’s Plymouth before switching to a Chevrolet. He won his first pole position in 1955 at Greenville-Pickens Speedway, Greenville, South Carolina and went on to finish the event in 3rd place. Welborn ended the season fourth in the 1955 NASCAR Winston Cup points standings with 9 top five results and 16 top 10s.
In 1956 he raced his own car in 5 races and one for and Julian Petty.
Welborn recorded his first victory in the Grand National Division on October 6, 1957 at Martinsville Speedway in the Old Dominion 500. Welborn recorded the victory, but didn't actually drive the car across the finish line. Lewis "Possum" Jones relieved Welborn at the mid-way point of the race, but Welborn got credit for the win. He only competed in 5 events during the season, but managed the record the 1 win and 3 top 5 finishes.
In 1958, driving for Julian Petty and Petty Enterprises he won five races, at Fayetteville, Martinsville, Greensboro, Winston-Salem, and Myrtle Beach. He also set the pole in qualifying at Greensboro. Having only competed in 18 of the years 51 events, he finished 149th in the points that year with 5 wins, 1 pole, 10 top 5s, and 15 top 10s.
In 1959, Welborn recorded 3 wins and 5 poles.
Welborn continued to compete in the Grand National Division thru the 1964 season driving his own cars and those of the Wood Brothers, W. J. Ridgeway, Fred Clark, Jack Smith, Joe Lee Jackson, Bud Moore, B. G. Holloway, J. C. Parker, Julian Petty, E. A. McQuaig, Fed Harb, and Cliff Stewart. In his final 3 events in 1964, he drove for Holman-Moody.
In addition to his Grand National Division wins, Welborn won the final three NASCAR Convertible Division championships, from 1955-57.
In his 13 year Grand National career, he recorded 7 poles, 9 wins, 58 top-5’s, and 102 top-10’s.