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).
Technical memo detailing modifications to increase push rod clearance in the cylinder head for the Wraith III and Bentley 111 models.
| Identifier | ExFiles\Box 158\4\ scan0252 | |
| Date | 2nd July 1938 | |
| BX/RS.{Sir Henry Royce's Secretary} [Struck through] Ram. [Handwritten] 1360 [Handwritten] DA.{Bernard Day - Chassis Design}4/G.2.7.38. c. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} Sides [Handwritten] WRAITH 111 and BENTLEY 111 - PUSH ROD CLEARANCE IN CYLINDER HEAD. Please receive herewith E.CD.775 Modifications to Cylinder Head to give increased push rod clearance. In accordance with the request in Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}15/JH.25.6.38. we have increased the clearance for push rods with the tube through the cylinder head by placing the tube on an axis parallel with the push rod and .025 offset outwards from the engine centre line, instead of it being vertical. This increases the clearance by about .050", the tube remaining at its original size. The corresponding holes for push rods in the gasket and also in the cylinder top face are altered to suit. The amount of gasket material between push rod hole and the outer edge of gasket is reduced by this alteration, and should be watched for any signs of oil leakage at this point. There is no casting alteration for cylinder head required. If the push rods still whip sufficiently to foul on the revised tube position it would be advisable to revert to shorter push rods by using the original design of tappet with the push rod cup located at the top of the tappet instead of at the bottom. Will you please detail and instruct for this experiment as soon as possible, so that the engine now being re-built for use in the Bentley 111 test car, can be altered accordingly. DA.{Bernard Day - Chassis Design} | ||