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 regarding 25HP ignition systems, spark plug testing, and compression pressure analysis.
| Identifier | ExFiles\Box 54\5\ Scan378 | |
| Date | 1st June 1932 | |
| X6095 R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Wst. c. to SS.{S. Smith} c. to Mr. c. to By.{R.W. Bailey - Chief Engineer} c. to E.{Mr Elliott - Chief Engineer} c. to FN. Hs{Lord Ernest Hives - Chair}/Wst.7.AMA.1.6.32. 25HP IGNITION. X1918 Re. R.2/M.30.5.32., we are arranging to send you, three of the K.L.G plugs mentioned. We have rigged up a special bench apparatus now, in which we can test plugs under pressure up to 160 lbs per sq.in. We are also constructing an H.T. voltmeter using a rectifying valve so that we can accurately measure plug voltages under all conditions on the engine and heated up under pressure on the bench. This apparatus will enable us to more intelligently investigate our ignition problems. With regard to the last para of your note we agree that the max compression pressure are higher at low speed full throttle due to the spark occurring practically at T.D.C. i.e./ the point of max pressure, and additionally we consider to:- /at (a) A larger volume of mixture drawn into the cylinder owing to the throttle being wide open and time longer. (b) The sparking plug being cooler due to the reduction in explosion frequency and to its being cooled by the incoming gas over a longer period of time. (c) Increase effect of leakages over the whole H.T. system occasioned by the sudden rise of plug voltage. We always find that the infallible test for magnetos and coils on the road is the "pick up" under load at slow speeds. Hs{Lord Ernest Hives - Chair}/Wst. | ||