Testing longer pistons for the Phantom II engine to address piston 'slap'.
| Identifier | ExFiles\Box 15\3\ Scan054 | |
| Date | 1st April 1931 | |
| X7040. E. {Mr Elliott - Chief Engineer} Hs. {Lord Ernest Hives - Chair} ✓ BY. {R.W. Bailey - Chief Engineer} Wor. {Arthur Wormald - General Works Manager} Mx {John H Maddocks - Chief Proving Officer} 6/H1.4.31. RECEIVED 17 APR 1931 H PHANTOM II. PISTONS. See memos. Mx {John H Maddocks - Chief Proving Officer} 8/T5.1.31., E5/M10.1.31. and E3/M.20.1.31. We have run two sets of pistons with skirt length increased by .8 and with increased expansion of bedding width. The pistons have been very satisfactory indeed. There has not been the slightest sign of "slap" when starting from cold, even at freezing temperatures. Examination and measurement of pistons show good bedding and sizes well maintained. There is no noticeable difference in the general running and smoothness of the engine. The average increase in weight is about 1 oz. per piston. The results so far are very encouraging. We have got to improve the life of the pistons, particularly for U.S.A. Phantom engines will develop piston "slap" in service after approximately 8,000 miles. Whilst the recent provision of positive lubrication will improve matters, it does not go far enough. It must be admitted that the rectification of piston "slap" should not be necessary after this mileage. Furthermore, it is an expensive maintenance charge. R.R.A.I. have always been in favour of the long piston and have used it on Phantom I, with, they claim, beneficial results for absence of piston knocks and long life. In order to produce these longer pistons, we have had to alter the production dies. Does you propose to run a 10,000 miles test with these long pistons before they can be adopted? Will you please give the whole matter your urgent consideration. | ||
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).