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).
Causes of excessive engine bedding due to undersized valves and the subsequent design alterations to rectify the issue.
| Identifier | ExFiles\Box 48\4\ Scan116 | |
| Date | 5th September 1923 | |
| -2- BY/Bhn7/DB.{Donald Bastow - Suspensions}5.9.23. Contd. chocking before full lift disappears. Since writing the above, the Inspection Dept: have reported that the engine on which excessive bedding had taken place, was due to valves being .015 to .020 undersize on the neck dia: where the wedges bed. Mr. Bailey has consented to pass valves for the present, which are -4 on this .250 dia; but for future production with the taper portion ground, we shall obtain -1 limits on dia: with the -4 limit there should be little bedding movement, and therefore we can pass engines where the initial assembly shows the wedge .010 - .012 below the level of the washer face. We give below copy of alteration No.8019/E to the above parts:- E.50147 - Wedge. Dia: of large end of taper alt:from .440 to .445 REASON. To give allowance for bedding in. "Smooth finish" added to taper bore. REASON. To obtain proper bedding on valve neck. E.50157 - Valve. "Smooth finish" added to 1 in 6 taper. REASON. To obtain proper bedding for wedge. .025 chamfer on end of valve altered to .015 and limit on .250 dia: alt:from -2 to -1. REASON. To give increased rocker contact surface. E.51895/6-Rocker Arms. The following note added - "This profile (relative to the bore and curved face) is important, and should be tested by gauge". We attach one blueprint of each of these altered drawings to Mr Swift's copy of this memo. BY/Bhn. | ||