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).
Conclusions report on an engine performance test regarding fuel types, spark plugs, and engine knock.
| Identifier | ExFiles\Box 150\1\ scan0165 | |
| Date | 7th August 1936 guessed | |
| - 3 - CONCLUSIONS The engine is in good condition and can be comfortably run on a No.1 Spirit as the makers claim - knock can be quite eliminated by use of the hand spark control. If Ethylized spirit is used knock is eliminated without using hand spark control, no appreciable gain in performance results with present spark timing but it is possible that by advancing the timing and running on Ethyl the car may be livelier and still not knock. No deterioration of the KLG 850 Plugs used has occurred since they were fitted (believed about 2,000 miles ago). This is a high compression engine (6.7 or 6.9 C.R.) susceptible to quite small amounts of carbon deposit and it seems probable that if much light running, such as town work, is done small accumulations of carbon accrue which are sufficient to induce a light knock on spirit of 70/71 O.N. - a hard fast run, or full throttle work such as was done at Brooklands in these tests, probably reduces the deposit and so cuts out knocking. The plugs and valves showed no signs of overheating during these tests and it is, therefore, unlikely that they will overheat under the less arduous conditions of road work. A slight rattle, which appears to come from the right hand side of the instrument board, or the scuttle, was noticed. This can be confused with the slight pinking produced at times on Shell Spirit. Retarding the spark cuts out the pinking but the noise referred to remains. [Signature] L.G.Callingham MANAGER - TECHNICAL & RESEARCH DEPARTMENT. OBSERVERS L.G.Callingham H.D.Parker. Air Temp. 18.5°C Baro: 29.9" Engine Water Temp: 80/83°C. | ||