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 memorandum detailing updates on timing chains, carburetors, combustion chambers, and engine design.
| Identifier | ExFiles\Box 124\3\ scan0279 | |
| Date | 12th December 1934 | |
| December 12, 1934 (1). We are quite satisfied with our timing chain picture as it now stands with regard to both noise and life. Considerable difficulty was experienced with the make of chain first used -- the production chains showing a rattle on fast idle at much earlier mileage than did the experimental samples. We have changed sources however, and are now using a chain with segmental bushings which are warped in manufacture so that they have to be sprung into place on assembly. This feature has cleaned up the rattle trouble completely. (2). We have experienced no slow running difficulties with the down-draft system as compared with the up-draft. We have changed to Stromberg carburetors and have made a slight change in the intake ports -- which changes have cleaned up the part throttle difficulties experienced on the 1934 jobs. (3). See attached curve sheet #1. (4). The "streamlined" combustion chamber and venturi ports are not entirely sales ballyhoo. The attached curve sheet (#2) - shows a comparison between the present series 40 type head and one made similar to our 50, 60 and 90 heads. Valve sizes and compression ratios were identical -- although the engine size at that stage of the 40 development, was somewhat smaller than the present engine. (5). On our long stroke engines the off-set pin is a decided advantage in preventing low speed piston slap. Since the 40 is using the same piston as the present 60 series -- the off-set feature is also used in it. We have done some work recently with light alloy pistons which seems to indicate that they will not require the off-set in our 40 engines -- but we have not had enough experience to commit ourselves on this point. (continued) | ||