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).
Letter to a customer regarding the supply of a high-compression cylinder head for a Bentley, with advice on reducing the compression ratio and suitable sparking plugs.
| Identifier | ExFiles\Box 89\3\ scan0012 | |
| Date | 14th August 1936 | |
| Expl. Dept. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}8/MJ. 14th. August, 1936. Mr. Cunningham, Cortachy Castle, Kirriemuir, Scotland. Dear Mr. Cunningham, I have fixed up some parts for your Bentley and in case our Conduit Street Office do not get an exact idea of what we are giving you I am writing to you directly. The cylinder head we are giving you is one which on an otherwise Standard Bentley engine average 80.5 m.p.h. for 450 miles in the Tourist Trophy Race last year. You may consider that the ratio is unpleasantly high for normal touring work and for the fuels you have available and so that you may be able to remedy matters if that is so, we are letting you have a plate which, when fitted between the cylinder block and crankcase, will reduce the compression ratio to 7.3/1. Sparking plugs I am afraid are going to be difficult because the Standard Champion has got such a short body that it will not fit into the pocket in the Bentley cylinder head. I would therefore recommend that you take a good supply of KLG.'s over with you. Maybe Champions would make some special plugs up for you if you insisted. The engine with the high compression head takes a bit of turning over; even with a Standard engine when I was in America two years ago I found that using Mobiloil Arctic I could not start at anything below 10°F.{Mr Friese} This being so, I have recommended that | ||