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).
Design decisions for the 7 CA car engine, including pistons, connecting rods, and camshafts.
| Identifier | ExFiles\Box 181\M11\ img027 | |
| Date | 1st May 1917 | |
| To EH. from R.{Sir Henry Royce} c.c. to J.{Mr Johnson W.M.} c.c. to Wor.{Arthur Wormald - General Works Manager} c.c. to By.{R.W. Bailey - Chief Engineer} c.c. to M.{Mr Moon / Mr Moore} [Handwritten] JULY / 17 [Typed] ORIGINAL [Typed] 7 CA [Handwritten] o (CAD) 4 [Typed] R1/B2:5:17. [Stamp] RECEIVED [Handwritten] X.681 Re Car Engine - 7 CA. [Typed] In reply to your memo EHL/AT19:4:17, I am hoping to be able to make a trip into the Midlands in the middle of June. I should be glad if this car (7 CA) was made into a fit state for me to criticise it. X.2369. The first thing to think about is the engine, and it was decided that if the 7 ring piston appeared to be impractical we should adopt the 5 ring piston having all the 4 upper narrow rings pinned, and a skirt below the lower scraper ring to reduce the tendency of piston knocks. X.2980 We have decided to use light connecting rods, the crank pin bored out and machined like an aero engine (Hawk), the lightest possible slipper flywheel, light valves with X.2938 strong springs, 30 degree face, and about .4" lift of the valve. Mr. Elliott is sending exact instructions. It will be remembered that the actual lift of the cam has to be more than the valve, owing to the decreased motion of the valve over that of the roller, the opposite to what takes place in the aero engines. We regret this but we cannot alter it. [Strikethrough] We think the only master cams that are available are those at present used for the "Eagle", but [/Strikethrough] We propose that new master cams shall be made to fit the present shaft. This will give a complete equipment of master cams for all times, if successful. [Handwritten] we must have truly ground camshaft to enable us to judge if valves are silent enough! [/Handwritten] It is not intended to interfere with the Falcon arrangements. Neither the proposed new, or the existing Falcon (Contd.) | ||