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).
Engine overheating issues and Wraith suspension problems.
| Identifier | ExFiles\Box 131\3\ scan0099 | |
| Date | 22th June 1939 | |
| - 4 - There is a good deal of evidence to indicate that the trouble is associated with local over-heating or steam pockets in the cylinder head, but this condition is not to be wondered at since more and more metal and porting has had to be found room for in the same overall dimensions since the days of the 20 HP., and the water passages are consequently much more restricted around the region of the valve seats. We believe that the gradual development of valve sinkage on 27.G.VI can only be due to silting up of certain of these already restricted water ways, and this in turn is aggravated by imperfect water circulation. We have, therefore, fitted a set of coolant jets identical with the scheme being used experimentally on B.5, arranged to direct the main stream of water towards the exhaust valve seatings, and we are doing a further 2,000 miles as quickly as possible to see whether they are of any benefit. We ought to get proof fairly quickly because, apart from the fitting of the coolant jets, there is no reason why the sinkage should not go on at the same rate, in fact, experience on the 25/30 HP. goes to show that once this trouble starts, it gets rapidly worse. The consistency or otherwise of the tappet clearances on 27.G.VI during the next 2,000 miles will, therefore, give us direct proof as to the value of the coolant jets. They can be applied easily to existing 25/30 HP. and Bentley cars if successful. 5. Wraith Suspension. There is a fair amount of criticism of the Wraith suspension, particularly on large limousines. The chief criticism is of extreme flexibility resulting in sickness or lack of control. The trouble is due to pitching combined with insufficient damping. As the result of experience on certain customers' cars, particularly Sir Ralph Millbourn's, we have been able to effect a marked improvement, and we believe that we need no longer fear that the large limousine must necessarily suffer from acute pitching as has been the case for so long Unfortunately, the treatment cannot be applied until after the complete car is on the road, as there is too much (continued) | ||