They are 4 cylinders if its an early corse (corsa B) is a belt driven engine(X1.2XE), ifs it's a later corsa (Corsa C) its chain driven(Z1.2XE), the 3 cylinder engine was a 1.0 (X1.0XE)
Sorry Toureman i didnt exactly explain myself very well, i meant the cams & valves were either driven off a timing belt or a cam chain is was just something else to look out for as the timing belt is a servicable item & Vauxhalls are a bit prone to belt failure the X1.2XE which is likely to be in a S reg Corsa comes as a kit with belt & pulleys in but usually the tensioner & tensioner bolt gets replaced as well.