Allen cut his teeth at the now-defunct Springfield Speedway. He started in Stock cars and moved up fast. He soon became a first class racer, winning the Missouri-Illinois stock car title. He began racing in the USAC Championship Car Series, racing in the 1961 through 1963 seasons with 15 starts, including the 1962 and 1963 Indianapolis 500 races. He finished in the top ten six times, with his best finish of 5th in 1962 at Syracuse.