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, ignition and steering issues with the 'Spectre' model following a test run on the Stelvio pass.
| Identifier | ExFiles\Box 91\4\ scan0235 | |
| Date | 3rd September 1935 | |
| x300a HOTEL DE FRANCE, CHATEAUROUX, Indre. France. To. Hs.{Lord Ernest Hives - Chair} From. G.W.H. 3. S. I. SPECTRECodename for Phantom III. Since our return to Châteauroux from the visit to the Stelvio, we have dismantled the bottom half of the Engine. The blade connecting rods have a considerable amount of slackness in the bearing. From the feel, we should say .030" on the diameter. Two fork rods also show definate slackness approximately .025" on the diameter. The crankshaft period between 30-50 MPH. causes a bad rattle of the rods to take place, choose what the oil pressure is when hot. With the oil cold there is no rattle. At speeds from 50 MPH. upwards, the Engine runs perfectly smooth but we dare not use full throttle too much, owing to the oil temperature becoming too high when the rattle can be heard. The run to the Stelvio showed up weaknesses in the Ignition system, especially with the speed of the Car being reduced for the climb of the Passes. One reason being the suppressors. The suppressors cut down the H T current too much, and with an overoiling Engine such as ours, the weak spark is not sufficient to keep the plugs firing. A bad feature with the suppressors, is apparently after being in use some time, the tapered screws which make the connection to the HT cables become loose and fail to connect. The flexible wire apparently breaks up. A further trouble with the High Tension wires, especially the outer ones is, the slot in the metallic tube is not large enough to give sufficient flexibility to the two cables, consequently the continual vibration of the cables breaks down the insulation, and a short circuit occurs in the metallic tube. We had to take the metallic tubes off owing to this on either side. The Ignition distributors are not satisfactory. On B side the bakerlite rubbing blocks wore away to such an extent, that there was no break of the contact on one, and only a few thousands of an inch on the other contact. This particular distributor has given trouble throughout the test. The bearing for the cam spindle has worn. The cam has quite a lot of side play which affects the make and break. The distributor head is also loose, the supporting bearing having worn. The trouble is similar to that experienced with the 25 H.P. The climb of the Stelvio showed that we have not sufficient turning circle. On the first climb six reverses was necessary, five being right hand turns. | ||