| Description | Date | Identifier | |
| Letter from B. S. Cunningham discussing the procurement and properties of 100 octane fuel compared to 87 octane fuel for engine use. | 3rd Nov 1927 | Box 174 \ 2 img228 | |
| Letter from Briggs Cunningham comparing his Cadillac V16 and Fiat 500 to a Bentley. | 29th Dec 1937 | Box 174 \ 2 img229 | |
| Letter from a New York attorney enclosing a newspaper clipping regarding workforce reductions at General Motors. | 29th Dec 1937 | Box 174 \ 2 img230 | |
| Letter to Mr. Cunningham discussing grouse shooting, car comparisons, and engine specifications. | 31th Dec 1937 | Box 174 \ 2 img231 | |
| Letter to B.S. Cunningham discussing the 'Fiat 500' car and a potential trip to America. | 31th Dec 1937 | Box 174 \ 2 img232 | |
| Letter to P.D. Herrick of Lycoming Manufacturing Co. regarding high lift cams with mushroom followers. | 7th Jan 1938 | Box 174 \ 2 img233 | |
| 'Brightray' coated exhaust valves and the material specifications for 'Silcrome' seat inserts. | 21th Jan 1938 | Box 174 \ 2 img234 | |
| Letter from Wilcox-Rich discussing cam design, valve lift, tappet types, and camshaft materials. | 28th Dec 1937 | Box 174 \ 2 img235 | |
| Letter from Wilcox-Rich Corporation discussing the material specifications of Silcrome seat rings for aircraft engines. | 29th Dec 1937 | Box 174 \ 2 img236 | |
| List of calculations for determining cam and tappet specifications and angles. | 27th Dec 1937 | Box 174 \ 2 img237 | |
| Page of calculations for lift on flank, lift on involute, total lift, and base circle radius. | 27th Dec 1937 | Box 174 \ 2 img238 | |
| Letter to Eaton Manufacturing Co. regarding hydraulic tappets and requesting a layout for oil feed on a side valve engine. | 24th Jan 1938 | Box 174 \ 2 img239 | |
| Letter to Studebaker Corporation seeking information on in-line eight engine bearing designs. | 5th Mar 1938 | Box 174 \ 2 img240 | |
| Letter to Buick's Chief Engineer discussing inline-eight engine designs, bearing configurations, and horsepower curves. | 7th Mar 1938 | Box 174 \ 2 img241 | |
| Request to Studebaker for a vacuum cylinder used for their assisted gear change. | 17th Mar 1938 | Box 174 \ 2 img242 | |
| Request to place an order with Studebaker Export Corporation for a vacuum cylinder. | 22th Apr 1938 | Box 174 \ 2 img243 | |
| Thank you letter to S. Sparrow of Studebaker Corporation for a Vacuum Cylinder. | 22th Apr 1938 | Box 174 \ 2 img244 | |
| Letter discussing developments on a 6-function valve, Packard soft-ride controls, and a new car project involving Walter Griswold. | 7th Apr 1938 | Box 174 \ 2 img245 | |
| Letter discussing US motor industry conditions, the 1928 models, and potential work for a person named Walter in Great Britain. | 2nd Jul 1928 | Box 174 \ 2 img246 | |
| Letter to Mr. Schubert regarding a factory re-organisation and a potential future meeting. | 10th May 1938 | Box 174 \ 2 img247 | |
| Inquiry to Studebaker Corporation regarding their overdrive system and 6-cylinder crankshaft torsional periods. | 11th May 1938 | Box 174 \ 2 img248 | |
| Letter from Studebaker discussing the inertia-operated overdrive and torsional characteristics of their engines. | 20th May 1938 | Box 174 \ 2 img249 | |
| Forced vibration, crankshaft deflection, and the performance of different engine vibration dampers. | 20th May 1938 | Box 174 \ 2 img250 | |
| Diagrams showing crankshaft torsional vibration at different RPMs for aluminium and cast iron pistons. | 11th Jul 1934 | Box 174 \ 2 img251 | |
| Diagrams comparing engine characteristics using Aluminium and Cast Iron pistons at various RPMs. | 11th May 1934 | Box 174 \ 2 img252 | |
| Letter from Wilcox-Rich to Mr. Robotham regarding difficulties experienced with hydraulic lifters. | 10th Jun 1938 | Box 174 \ 2 img253 | |
| Letter responding to a query about hydraulic lash adjusters and their issues. | 21th Jun 1938 | Box 174 \ 2 img254 | |
| Letter from Wilcox-Rich regarding hydraulic lash adjusters and a proposal for collaboration. | 6th Jul 1938 | Box 174 \ 2 img255 | |
| Letter from Wilcox-Rich regarding oil lubrication system drawings and oil pressure specifications. | 6th Jul 1938 | Box 174 \ 2 img256 | |
| Confidential letter to V.C. Young of Wilcox-Rich Manufacturing Co. regarding a request for data on a novel engine. | 16th Jul 1938 | Box 174 \ 2 img257 | |
| List of points of interest regarding American automotive design and technology for an upcoming visit to the U.S.A. | 25th Aug 1938 | Box 174 \ 2 img258 | |
| List of queries regarding American automotive developments, testing, and materials. | 25th Aug 1938 | Box 174 \ 2 img259 | |
| Letter from J. S. Inskip Inc. in New York to W. A. Robotham in Derby concerning US market feedback and car consignment. | 17th Aug 1936 | Box 174 \ 2 img260 | |
| Letter of introduction for an engineer visiting Detroit to survey the American motor-car industry. | 29th Aug 1936 | Box 174 \ 2 img261 | |
| Letter to J.S. Inskip regarding company re-organisation and a visit from Dr. Llewelyn Smith. | 27th Aug 1938 | Box 174 \ 2 img262 | |
| Correspondence regarding the Diesel Engine Division and a list of useful industry contacts. | 29th Aug 1936 | Box 174 \ 2 img263 | |
| Letter of introduction for Dr. Llewelyn Smith for his visit to The Eclipse Aviation Co. in the USA. | 30th Aug 1938 | Box 174 \ 2 img264 | |
| Letter of introduction for Dr. Llewelyn Smith to Mr. Herrick of Lycoming Motors. | 30th Aug 1938 | Box 174 \ 2 img265 | |
| Letter of introduction for Dr. Llewelyn Smith to Mr. E.D. Geyer of General Motors in Ohio, USA. | 30th Aug 1938 | Box 174 \ 2 img266 | |
| Letter of introduction for Dr. Llewelyn Smith to Mr. J.B. Taylor in New York. | 30th Aug 1938 | Box 174 \ 2 img267 | |
| Letter of introduction for Dr. Llewelyn Smith's visit to the United States. | 30th Aug 1938 | Box 174 \ 2 img268 | |
| Letter of introduction for Dr. Llewelyn Smith to Mr. J.M. Crawford of Chevrolet Motor Co. | 30th Aug 1938 | Box 174 \ 2 img269 | |
| Letter of introduction for Dr. Llewelyn Smith, who is visiting the USA on behalf of the company, to Mr. L.P. Saunders of General Motors. | 30th Aug 1938 | Box 174 \ 2 img270 | |
| Letter of introduction for Dr. Llewelyn Smith for his visit to America. | 30th Aug 1938 | Box 174 \ 2 img271 | |
| Letter of introduction for Dr. Llewelyn Smith to Mr. Chayne of Buick Motor Co. during a visit to the USA. | 30th Aug 1938 | Box 174 \ 2 img272 | |
| Letter of introduction for Dr. Llewellyn Smith to H.T. Woolson, Chief Engineer at Chrysler Corporation. | 30th Aug 1938 | Box 174 \ 2 img273 | |
| Letter of introduction for Dr. Llewelyn Smith to Mr. S. Sparrow of the Studebaker Corporation. | 30th Aug 1938 | Box 174 \ 2 img274 | |
| Letter of introduction for Dr. Llewelyn Smith to V.C. Young of the Wilcox-Rich Manufacturing Corporation. | 30th Aug 1938 | Box 174 \ 2 img275 | |
| Letter of introduction for Dr. Llewelyn Smith to Mr. S. Sparrow of Studebaker Corporation. | 30th Aug 1938 | Box 174 \ 2 img276 | |
| Letter of introduction for Dr. Llewelyn Smith to Mr. F.C. Mock of Bendix Products Corporation. | 30th Aug 1938 | Box 174 \ 2 img277 | |
| Letter of introduction for Dr. Llewelyn Smith's visit to the United States. | 30th Aug 1938 | Box 174 \ 2 img278 | |
| Letter concerning the potential manufacturing of Wilcox Rich tappets and a request for dimensions. | 19th Sep 1938 | Box 174 \ 2 img279 | |
| Letter from US retailer J.S. Inskip to Mr. W.A. Robotham discussing market expansion in America and a visit from Dr. Smith. | 6th Sep 1938 | Box 174 \ 2 img280 | |
| Letter from Wilcox-Rich discussing a quotation for Zero-Lash hydraulic valve lifters based on blueprint PD-252. | 31th Oct 1938 | Box 174 \ 2 img281 | |
| Letter to Thompson Products Inc. seeking advice on salt-cooling versus copper-cooling for side valve engines. | 18th Nov 1938 | Box 174 \ 2 img282 | |
| Inquiry to Lycoming Motors regarding high-output side valve engines and the types of exhaust valves used. | 18th Nov 1938 | Box 174 \ 2 img283 | |
| Letter to Eaton Manufacturing Company requesting information on hydraulic valve adjusters and tappets for side valve engines. | 18th Nov 1938 | Box 174 \ 2 img284 | |
| Article from The Automobile Engineer on poppet valves and developments in cooling methods. | 1st Sep 1931 | Box 174 \ 2 img285 | |
| Page detailing the development and various designs of engine valves, including sodium-cooled types. | 1st Sep 1931 | Box 174 \ 2 img286 | |
| Page from 'The Automobile Engineer' magazine discussing copper-filled valves, valve cooling, and valve seat materials. | 1st Sep 1931 | Box 174 \ 2 img287 | |
| Analysis of valve-seat 'pick-up' issues, heat transfer properties of valve materials, and a review of a paint-spraying apparatus. | 1st Dec 1938 | Box 174 \ 2 img288 | |
| Letter to Studebaker Corporation with technical questions about exhaust valves, dampers, and gearboxes. | 1st Dec 1938 | Box 174 \ 2 img289 | |
| The concluding page of a letter to S. Sparrow, Esq. regarding a request for information. | 1st Dec 1938 | Box 174 \ 2 img290 | |
| Letter to Chrysler Corporation seeking information on exhaust valve temperature and design. | 2nd Dec 1938 | Box 174 \ 2 img291 | |
| Letter to the Chief Engineer of Olds Motor Works Division regarding exhaust valve performance and design. | 2nd Dec 1938 | Box 174 \ 2 img292 | |
| Letter asking S. Heron of Ethyl Export Corporation for information on engine exhaust valve technology and performance. | 2nd Dec 1938 | Box 174 \ 2 img293 | |
| Letter from Wilcox-Rich discussing sodium-cooled valves and coolant mixtures. | 5th Dec 1938 | Box 174 \ 2 img294 | |
| Letter to S. Sparrow of Studebaker Corporation regarding the conclusion that excessive valve temperature is due to high-speed detonation. | 23th Dec 1938 | Box 174 \ 2 img295 | |
| Letter from Lycoming Manufacturing Company discussing their methods for engine valve cooling. | 6th Dec 1938 | Box 174 \ 2 img296 | |
| Letter from Lycoming Manufacturing Company detailing methods for improving engine volumetric efficiency and reducing exhaust valve temperatures. | 6th Dec 1938 | Box 174 \ 2 img297 | |
| Letter from Thompson Products Inc. regarding copper-cooled versus sodium-cooled engine valves. | 12th Dec 1938 | Box 174 \ 2 img298 | |
| Letter from Studebaker Corporation discussing exhaust valve temperatures, cooling methods, and engine flare-up issues. | 14th Dec 1938 | Box 174 \ 2 img299 | |
| Engine after-firing, crankshaft vibration dampers, and overdrive gearbox kickdown functionality. | 14th Dec 1938 | Box 174 \ 2 img300 | |
| Letter from Olds Motor Works to W. A. Robotham regarding general opinions on sodium-cooled exhaust valves. | 16th Dec 1936 | Box 174 \ 2 img301 | |
| Letter from S.D. Heron of Ethyl Gasoline Corporation regarding exhaust valve temperature. | 19th Dec 1938 | Box 174 \ 2 img302 | |
| Letter to A.T. Colwell of Thompson Products, Inc., regarding copper-cooled and sodium-cooled valves. | 22th Dec 1938 | Box 174 \ 2 img303 | |
| Letter to Lycoming Manufacturing Company regarding criticisms of exhaust valves and counter-boring valve guides. | 22th Dec 1938 | Box 174 \ 2 img304 | |
| Letter to S.D. Heron of Ethyl Gasoline Corporation regarding valves. | 2nd Jan 1938 | Box 174 \ 2 img305 | |
| Letter to Chrysler Corporation thanking them for information on the free flow of gas and reducing valve temperature. | 3rd Jan 1938 | Box 174 \ 2 img306 | |
| Letter from Wilcox-Rich discussing difficulties and developments in sodium-cooled valve technology. | 5th Dec 1939 | Box 174 \ 2 img307 | |
| Letter from Lycoming Manufacturing Company discussing the design and materials for exhaust valve guides, specifically concerning counter boring and cooling. | 10th Jan 1939 | Box 174 \ 2 img308 | |
| Blueprint for a valve guide with dimensions and manufacturing notes. | 10th Jan 1939 | Box 174 \ 2 img309 | |
| Blueprint for a Valve Stem Guide. | 10th Jan 1939 | Box 174 \ 2 img310 | |
| Letter from Thompson Products, Inc. regarding the use and cost of sodium-cooled valves. | 18th Jan 1939 | Box 174 \ 2 img311 | |
| Letter discussing a new Bentley design and the need for independent front suspension for rough roads. | 18th Jan 1939 | Box 174 \ 2 img312 | |
| Letter comparing the acceleration of American cars with a special 8-litre Bentley. | 18th Jan 1939 | Box 174 \ 2 img313 | |
| Letter from a customer detailing a car breakdown and subsequent troubleshooting. | 18th Jan 1939 | Box 174 \ 2 img314 | |
| Report detailing the diagnosis and repair of a carburettor float issue, and a query on acceleration performance. | 11th Mar 1939 | Box 174 \ 2 img315 | |
| Letter to B.S. Cunningham discussing the performance of a Streamline Bentley, with comparisons to an American Buick. | 11th Mar 1939 | Box 174 \ 2 img316 | |
| Letter to B.S. Cunningham discussing the interior space of a standard Bentley. | 11th Mar 1939 | Box 174 \ 2 img317 | |
| Letter from B. S. Cunningham to Mr. Robotham discussing car features and performance. | 11th Mar 1939 | Box 174 \ 2 img318 | |
| Letter discussing preferences for car design, suspension, and performance. | 11th Mar 1939 | Box 174 \ 2 img319 | |
| Letter from B.S. Cunningham requesting a performance test report on a new Bentley for comparison with a Buick Century. | 11th Mar 1939 | Box 174 \ 2 img320 | |
| Letter discussing motor changes, horsepower gains, and comparisons between a Buick and a Bentley engine. | 12th Apr 1939 | Box 174 \ 2 img321 | |
| Notification of a vacancy in the Rolls-Royce Defence Unit troop for a Mr. H. M. White. | 12th Apr 1939 | Box 174 \ 2 img322 | |
| Letter to a customer discussing the performance of a new Bentley and a special Buick. | 14th Apr 1939 | Box 174 \ 2 img323 | |
| Letter to Mr. Cunningham regarding the collection of his Bentley and a proposed meeting. | 28th Jul 1939 | Box 174 \ 2 img324 | |
| Letter from Briggs Cunningham to Mr. Robotham discussing a meeting, cars, and a potential trade. | 1st Aug 1960 | Box 174 \ 2 img325 | |
| Briggs S. Cunningham's discussions with W.O. Bentley and Lagonda regarding a potential new car build. | 1st Aug 1960 | Box 174 \ 2 img326 | |
| Letter from a customer to Bentley Motors expressing dissatisfaction with a car's performance and preference for a Mulliner body over the new streamline design. | 2nd Jul 1934 | Box 174 \ 2 img327 | |
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