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).
The performance of the 'SS' engine, detailing running conditions, induction distribution, and optimal camshaft timings.
| Identifier | ExFiles\Box 13\2\ 02-page013 | |
| Date | 20th September 1928 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/ACL. c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} X7090 Hs{Lord Ernest Hives - Chair}/ACL1/LG20.9.28. 'SS{S. Smith}' ENGINE. X7090 X9070 X1452 X7771 Engine No. SS{S. Smith}-3. Running conditions: Claudel Hobson Carburetter (Eagle 1X) Hot spot in action (water temperature 75°C) Open exhaust. 116° Camshaft (Cam forms E.77855/4). The distribution of the six port induction pipe at full throttle has been found to be very good. At high speeds it is very even, but at low speeds the centre cylinders Nos. 3 and 4 are slightly weak. Upon removing the fishtail nozzle E.77799 from the induction pipe, the distribution becomes perfectly even at all speeds. Owing to the throttle of the Claudel Hobson carb. being asymmetrical with relation to the branches of the induction pipe, the distribution under throttled conditions was not observed. The 116° camshaft has been tried with various timings, but the best power curve is given with the following (.020 clearance). Inlet opens 21° After T.D.C. Inlet closed 45° After B.D.C. Exhaust opens 36° Before B.D.C. Exhaust closes at T.D.C. With this timing the power is greater at the higher contd:- | ||