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).
Conversation with Strombergs regarding carburetter flooding and recommendations to prevent percolation.
| Identifier | ExFiles\Box 173\4\ img184 | |
| Date | 1st January 1936 | |
| To Sg.{Arthur F. Sidgreaves - MD} c. to Wor.{Arthur Wormald - General Works Manager} c. to R.{Sir Henry Royce} c. to By.{R.W. Bailey - Chief Engineer} c. to Hdy.{William Hardy} 23A Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}5/KW.1.1.36. The following is a copy of a memo. received from Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} dated 7.12.35. "I went to Strombergs on Thursday and told them about the flooding complained of in Rm{William Robotham - Chief Engineer}'s cables. They expect their carburetters to flood on a 14% gradient (very nearly 1 in 7) and to obtain this the level is 9/32 below the main jet. The auxiliary jets are at or just below the petrol level and are shut off when the throttle is closed. The pump mechanism controls the opening of these jets. Cadillacs have had cases where this valve leaks and the carburetter floods all the time. Their only recommendations for obtaining a 1 in 5 flood gradient were either to put the float at the side, which they know cuts out on corners, or tilt the whole carb. forwards the necessary angle, about 5° on our manifold as the engine slopes 1½° backwards. To prevent percolation in the existing type of carburetter, the following features help - (1) At least 5/8" asbestos packing between the carb. and manifold. (2) Venting of the float chamber lid{A. J. Lidsey} by an affair like our axle breathers with a gauge to prevent bubbles of petrol escaping. They have never had a fire because of venting under the bonnet. (3) The greatest distance possible between the carb. and the bonnet top when the temperature is always high. (4) Cool pipe lines and pump so that boiling in these places does not vent through the float chamber. (5) Deflectors to prevent exhaust manifold heat reaching the carbs. | ||