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 development report for the Bentley 60, detailing issues from a 100-hour endurance test and proposed solutions.
| Identifier | ExFiles\Box 161a\3\ scan0013 | |
| Date | 6th January 1939 | |
| - 12 - BENTLEY 60. ENGINE DEVELOPMENT. 6-cylinder High Power Unit. Development work is proceeding on this unit with the object of running 100 hours endurance. Various troubles have arisen and are being eliminated, in particular, wear on the distributor drive when a cast iron camshaft was used. Valve Spring Failures. Trouble with the crankshaft damper overcome by fitting an oilite bush. These are all minor points which do not present any fundamental difficulty. A further problem which has been encountered has been that of gasket burning under endurance running conditions. So far it appears that this has been eliminated by increasing the throat area, but we shall know more about it after the next endurance run. There is a tendency for this engine to run after switching off, which, of course, has also been a characteristic of certain 25/30 units, i.e., the one fitted to Sg{Arthur F. Sidgreaves - MD}'s car. This trouble has been eliminated by using sodium cooled exhaust valves, but we hope to achieve the same result by improvement to the arrangement of the exhaust valve guide. The cylinder pattern has been altered to improve the valve guide cooling as a result of these tests, and will be tried out in due course. We expect to be in a position to start a serious endurance run in about a fortnight's time. On this B.60 engine we have thrown away the somewhat expensive spring drive which has always been a characteristic of our 6-cylinder engines. The spring drive prevents high-speed crankshaft oscillations causing undue timing gear wear. Investigation we have carried out suggests that in order to do away with this spring drive on either B.V. or B.60 engine unit, it may be necessary to increase the crankshaft journals by ¼". Such a crankshaft could be accommodated without difficulty in the B.60 engine unit, and an engine is being built up with such a shaft for test. | ||