From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Notes on Jaguar cars and engines following a visit to the S.S. Motor Car Co.
| Identifier | ExFiles\Box 126\5\ scan0028 | |
| Date | 2nd December 1937 | |
| By.{R.W. Bailey - Chief Engineer} from Rm.{William Robotham - Chief Engineer} c. Hs.{Lord Ernest Hives - Chair} Rm{William Robotham - Chief Engineer}8/R.2.12.37. JAGUARS. For record purposes here are notes made in connection with our visit to the S.S. Motor Car Co. This Company last year turned out between 4,000 and 4,500 cars consisting of 1½-litres and 2½-litres. We gather that the ratio of cars sold was 2 : 1 in favour of the smaller engine. S.S. admit that they do not make much money on the small car. On the original 2½-litre they use a number of parts which are common to Standards. This engine has now been re-designed and no parts used are common to Standards. The 3½-litre engine is the 2½-litre with no water between the cylinder bores. They have not, of course, as yet had much experience with the 3½-litre, but the 2½-litre cars have run as much as 50,000 miles. Jaguars state that at the completion of this mileage it was not necessary to adjust the bearings or to re-bore the cylinders. Our main interest in the car itself was concentrated in the engine as this is almost exactly like the unit proposed for Bentley 50. The crankshaft has 2½" journals and 2" pins, exactly the same dimensions as we have on Wraith. Having no water between the cylinder bores, the engine is 2" shorter than the Wraith, and, therefore, must have that much space less for bearings and water between the valves. We drove one of the cars on the road, and made a point of trying to detect where the half crank critical speed was located because this engine has no crankshaft damper. In spite of the fact that the car was alleged to have run about 25,000 miles, it was most difficult to find this crankshaft period, but it appeared to be @ 2,900 r.p.m. This puts the major critical at nearly 6,000 r.p.m. which is higher than we have ever previously experienced on a 7-bearing 6-cylinder engine, particularly when fitted with balance weights. | ||