Best vid I could find of MH434 a mkIX spitfire with type 66 Merlin engine. From 5.35 to 6.25:
Any kind of visible flame on startup is very unusual unless this is due to overpriming of the engine. A spitfire in good condition will start with less than one turn of the prop. They can throw out quite a bit of smoke though for a couple of seconds. See here, a mk1a: