From a History of the Royal Air Force:-
"The Messerschmitt's Daimler-Benz DB 601A engine had the advantage of fuel injection which enabled the aircraft to bunt (push negative g at the top of a manoeuvre or climb) without losing power. The Merlin engine of the Spitfire had a float-type carburettor which necessitated the aircraft performing the longer manoeuvre of rolling inverted before diving to maintain positive g, thus preventing the engine from cutting out as a result of fuel starvation"