CLERMONT, IN - JULY 26: Mark Donohue (center), Al Unser (left), and Unser's chief mechanic George Bignotti chat before the start of the USAC INDY 150 Champ Car Race held on the road course at Indianapolis Raceway Park (IRP) on July 26, 1970 in Clermont, Indiana. (Photo by Alvis Upitis)