Weld raced in the USAC Championship Car series in the 1965–1972 seasons, with 36 career starts, including the 1970 Indianapolis 500. He finished in the top ten 11 times, with his best finish in 4th position in 1970 at Sacramento.
Weld competed in USAC Championship Car races from 1965 to 1972, achieving a total of 36 starts, including the 1970 Indianapolis 500. He finished within the top ten on 11 occasions, with his best performance being fourth place at Sacramento in 1970.