 Complete the following phrase:  Amon won the pre-season Silverstone International Trophy, but once the F1 season began he found himself prevented from converting good qualifying positions into good results. He qualified second behind Stewarts Tyrrell-March for the season-opening South African Grand Prix only for his own March to overheat within fourteen laps. Amon then qualified sixth for the Spanish Grand Prix only for his Marchs Ford-Cosworth DFV engine to expire within ten laps. He qualified and ran second in the 