`  ::::::No, I don't have that book. The stroke is given as 5.08 inches in other sources that I have seen (Rolls-Royce Heritage Trust response on a forum which can't be used as a source), this might explain the discrepancy when using a calculator. Another factor with this engine is the apparent use of articulated connecting rods, the stroke of the master rod and the three articulated rods for each cylinder row would be slightly different. We don't know which stroke figure is being given.   `