The question I was trying to ask is why the combination of 98mm bore, four cylinders and 4.2 litre displacement occurs so often. This combination means the engines all share the same stroke, Mike Halloran's comment about being tooled up for a particular design might also apply to crankshaft...
Can anyone explain why so many engines use a 98mm bore. As far backs the 1920s this bore appeared in a Vauxhall 4.2 litre 4 cylinder petrol engine, (designed by Laurence Pomeroy). The same dimensions are used in many current 4 cylinder diesel engines fitted to Fiat, Ford, Fendt, International...
