INDIANAPOLIS (AP) — Greg Weld, who won 21 U.S. Auto Club sprint car races and was the series national champion in 1967, died Monday. He was 64.

The cause of death was not immediately known.

The Indianapolis Motor Speedway said Weld died in Kansas City, Mo., where his company, Weld Racing Wheels, is based.

Weld passed his Indianapolis 500 rookie test in 1965, when he was the USAC sprint car runner-up to Johnny Rutherford, but his only start at the Speedway was in 1970, when he finished 32nd. By that time, however, his growing business was taking up much of his time, and he finished his driving career at age 30 with a fourth-place finish in the 1974 USAC Silver Crown series. In his final race, he was runner-up to A.J. Foyt in a 50-mile sprint car race on the Indiana State Fairgrounds dirt track two nights before the 1974 Indy 500.

A funeral service is scheduled for Friday at the Kansas City Baptist Temple.