| Description | Date | Identifier | |
| Spring experiments for the GYL-25 Sales Trials Car following feedback from Mr. Royce. | 20th Jul 1928 | Box 58 \ 1 Scan158 | |
| Request to borrow the Barkerlite Trials car CAJ.23 to carry out an experimental test on its rubber engine mounting. | 24th Aug 1928 | Box 58 \ 1 Scan159 | |
| Brake servo 'snatching' issue on a London Open Touring Trials car. | 24th Aug 1928 | Box 58 \ 1 Scan160 | |
| Trial and sale of chassis GAJ-53 with an experimental engine mounting. | 14th Sep 1928 | Box 58 \ 1 Scan161 | |
| Experimental engine feet on car GAJ-53, recommending they be replaced with standard parts before sale. | 14th Sep 1928 | Box 58 \ 1 Scan162 | |
| The production and instruction of necessary pieces for chassis GSK-55. | 8th Nov 1928 | Box 58 \ 1 Scan163 | |
| Request for the loan of a 20 HP Trials car to investigate a knocking issue in the rear shock absorbers. | 2nd Nov 1928 | Box 58 \ 1 Scan164 | |
| Request for the latest porcelain cleanable plugs for the New Phantom and Goshawk models. | 26th Jun 1925 | Box 58 \ 1 Scan165 | |
| On the 20 HP 10,000 miles test at Chateauroux, detailing issues with overheating spark plugs and the engine mounting. | 14th Jan 1929 | Box 58 \ 1 Scan166 | |
| Pre-ignition, ignition plug temperature, and water cooling issues in an aluminium cylinder head. | 10th Apr 1929 | Box 58 \ 1 Scan167 | |
| Proposals and considerations for improving engine performance, focusing on compression ratio, water cooling of plugs, and ignition advance. | 10th Apr 1929 | Box 58 \ 1 Scan168 | |
| Conclusions from a cylinder head test, with proposals for modification. | 30th May 1930 | Box 58 \ 1 Scan169 | |
| Tendency to misfire on high compression 20/25HP engines and recommending a smaller spark plug gap. | 30th May 1930 | Box 58 \ 1 Scan170 | |
| Note regarding sparking plug voltages on the 20/25 chassis, referencing another report. | 9th Feb 1931 | Box 58 \ 1 Scan171 | |
| The likely standardisation of the smaller 14 mm sparking plug. | 23th Oct 1931 | Box 58 \ 1 Scan172 | |
| Fix for an oil leak on the rear end of EAC and 20 HP engines, involving the attachment of a cover. | 27th Aug 1925 | Box 58 \ 1 Scan173 | |
| Consideration of a 10,000-mile test for a 20 HP 'India' Production Car. | 1st Oct 1925 | Box 58 \ 1 Scan174 | |
| Query about non-standard parts, lubrication, and alterations for a 20 HP 'India' car following a 10,000-mile test. | 23th Sep 1925 | Box 58 \ 1 Scan175 | |
| Oil test and a revised lubrication procedure for the propeller shaft joints on a 20 HP 'India' car. | 10th Oct 1925 | Box 58 \ 1 Scan176 | |
| Need for a lubrication piping system to reach inaccessible points on owner-driver cars. | 13th Oct 1925 | Box 58 \ 1 Scan177 | |
| Query regarding the necessity of a lubricator for the servo drive on the India Gearbox. | 14th Dec 1925 | Box 58 \ 1 Scan178 | |
| Overoiling issue on 20-HP cars and the proposal to supply depots with new piston rings. | 21th Jan 1926 | Box 58 \ 1 Scan179 | |
| Recommending a standardized gear oil for axles and gearboxes on 20 HP and Phantom models. | 23th Dec 1926 | Box 58 \ 1 Scan180 | |
| Automatic system for extra cylinder lubrication. | 26th Nov 1931 | Box 58 \ 1 Scan181 | |
| Clarifying a misunderstanding regarding the 20/25 HP lubrication system and the sourcing of parts. | 14th Jul 1932 | Box 58 \ 1 Scan182 | |
| Tests conducted on a thermostat from Messrs Smith & Sons for extra cylinder lubrication. | 10th Oct 1932 | Box 58 \ 1 Scan183 | |
| Unsuccessful testing of thermostat bellows for extra cylinder lubrication. | 14th Oct 1932 | Box 58 \ 1 Scan184 | |
| Graph showing the rating of bellows for a J III Cylinder Oil Thermostat, plotting extension against load. | 12th Oct 1932 | Box 58 \ 1 Scan185 | |
| Complaint of overoiling on a 20-HP Chassis from America. | 18th Dec 1925 | Box 58 \ 1 Scan186 | |
| Letter from the American branch to London regarding an overoiling engine issue on a 20-HP car. | 4th Dec 1925 | Box 58 \ 1 Scan187 | |
| Requesting an experimental varnished cambric covered Maconites H.T. cable for a Phantom II chassis. | 20th Nov 1929 | Box 58 \ 1 Scan188 | |
| Letter from The Macintosh Cable Company Ltd. regarding the supply and testing of Maconita H.T. Ignition Flexible cable. | 2nd Dec 1929 | Box 58 \ 1 Scan189 | |
| Comparative tests of Maconite, Gloverite, Super Glover, and Helsby H.T. ignition cables on a Phantom I chassis. | 1st Dec 1929 | Box 58 \ 1 Scan190 | |
| Results of physical and chemical tests on various dielectric cable materials. | 1st Dec 1929 | Box 58 \ 1 Scan191 | |
| Test results on four different cable insulation materials, including voltage breakdown and flammability. | 1st Dec 1929 | Box 58 \ 1 Scan192 | |
| Test report on the performance of different types of electrical cable insulation under high voltage and heat stress. | 12th Dec 1929 | Box 58 \ 1 Scan193 | |
| Test report comparing the insulation performance of Gloverite, Super Glover, Maconit, and Helsby cables after 10,000-mile road tests. | 6th Dec 1929 | Box 58 \ 1 Scan194 | |
| Comparative electrical tests on Maconite, Gloverite, and Helsby cables. | 6th Dec 1929 | Box 58 \ 1 Scan195 | |
| Comparison of Maconite, Cloverite, and Super Clover H.T. cables and their durability on Phantom I and Phantom II chassis. | 6th Dec 1929 | Box 58 \ 1 Scan196 | |
| Heat damage to H.T. wires from the exhaust tube and proposing solutions such as shielding or alternative cable materials. | 1st Dec 1929 | Box 58 \ 1 Scan197 | |
| Proposing experimental ignition wire tubing materials for the Phantom II. | 9th Dec 1929 | Box 58 \ 1 Scan198 | |
| Requesting the fitting of special heat and oil resistant ignition H.T. cables to test chassis 23-EX. | 9th Jan 1930 | Box 58 \ 1 Scan199 | |
| New type of cellulose varnished cambric covered maconite H.T. cable for trial on experimental cars. | 1st Jan 1930 | Box 58 \ 1 Scan200 | |
| Recommendation to use Cellulose Varnished Cambric Covered Maconite H.T. Cable for Sir Henry Segrave's two engines due to its good protection from oil and petrol. | 5th Feb 1930 | Box 58 \ 1 Scan201 | |
| Request to fit cellulose varnished cambric covered maconite H.T. wiring for a 10,000-mile test on 14-G4. | 6th Feb 1930 | Box 58 \ 1 Scan202 | |
| Letter to The Macintosh Cable Co. Ltd. regarding test results and issues with a sample of H.T. cable. | 11th Feb 1930 | Box 58 \ 1 Scan203 | |
| Letter to The Macintosh Cable Co. Ltd enclosing a copy of a previously misplaced letter. | 18th Feb 1930 | Box 58 \ 1 Scan204 | |
| Letter from The Macintosh Cable Company Ltd acknowledging a memo regarding Lacquered Cambric Covered H.T. Cable. | 19th Feb 1930 | Box 58 \ 1 Scan205 | |
| Comparison of cellulose lacquered cambric covered maconite H.T. cables for car and 'R' engines. | 18th Mar 1930 | Box 58 \ 1 Scan206 | |
| Cellulose lacquered cambric covered maconite H.T. cable for car and 'R' engines. | 25th Mar 1930 | Box 58 \ 1 Scan207 | |
| Letter concerning the quality and surface finish of lacquered cambric covered H.T. cable. | 26th Mar 1930 | Box 58 \ 1 Scan208 | |
| Extract from a report on the condition of high-tension wires after 5,000 and 10,000 miles of use. | 26th Mar 1930 | Box 58 \ 1 Scan209 | |
| Request to order an improved Cellulose Lacquered Cambric Covered Maconitem H.T. Cable for the Phantom II chassis. | 28th Mar 1930 | Box 58 \ 1 Scan210 | |
| Extract from a report on the performance of high tension cables after 14,000 miles. | 5th Apr 1930 | Box 58 \ 1 Scan211 | |
| Improved cellulose lacquered cambric covered maconite H.T. cable and its fitting to experimental chassis. | 23th May 1930 | Box 58 \ 1 Scan212 | |
| Cellulose Lacquered Cambric Covered Maconita H.T. Cable and its fitting to chassis 18-EX and 24-EX. | 23th Jun 1930 | Box 58 \ 1 Scan213 | |
| Extract from G.W. Hancock's report on the condition of Maconinte ignition cables on car 24-EX after 6,000 miles. | 20th Jul 1930 | Box 58 \ 1 Scan214 | |
| The failure of cambric covered H.T. ignition cables after testing, recommending a woven asbestos alternative. | 18th Aug 1930 | Box 58 \ 1 Scan215 | |
| Extract from G.W. Hancock's report on the poor condition of Maconita ignition cables on chassis 24-EX after 10,000 miles. | 15th Aug 1930 | Box 58 \ 1 Scan216 | |
| The performance of Champion sparking plugs types AE.4, AE.9, and AE.1. | 23th Mar 1928 | Box 58 \ 2 Scan001 | |
| Letter to Champion Sparking Plug Co. Ltd. regarding the return and testing of various spark plugs. | 13th Apr 1928 | Box 58 \ 2 Scan002 | |
| Follow-up letter regarding Giomme's sparkling plugs from the W.B. Kahn Company Ltd. | 6th Jan 1930 | Box 58 \ 2 Scan003 | |
| The test results of Igna-Segrave sparking plugs on a 20 HP engine. | 9th Jan 1930 | Box 58 \ 2 Scan004 | |
| Follow-up letter requesting the return of Giomme's sparking plugs. | 23th Jan 1930 | Box 58 \ 2 Scan005 | |
| Giomme's Sparking Plugs and correspondence with W. B. Kahn Co., Ltd. | 14th Feb 1930 | Box 58 \ 2 Scan006 | |
| Letter from W. B. Kahn Company Ltd. chasing up a report on Giomme's Sparking Plugs. | 13th Feb 1930 | Box 58 \ 2 Scan007 | |
| Failure and subsequent disposal of Ciomme's Sparking Plugs. | 15th Feb 1930 | Box 58 \ 2 Scan008 | |
| Letter from Lissen Limited proposing a test of their new aviation spark plugs, as suggested by the Air Ministry. | 29th Aug 1930 | Box 58 \ 2 Scan009 | |
| Continuation sheet from Lissen Limited regarding aircraft plugs with steel bodies. | 29th Aug 1930 | Box 58 \ 2 Scan010 | |
| Letter regarding the forwarding of six B.S.2. type sparking plugs received from Messrs. Lissen and their previous tests. | 5th Sep 1930 | Box 58 \ 2 Scan011 | |
| Letter from Lissen Limited to Colonel Fell regarding a new type of sparking plug for aircraft engines. | 1st Sep 1930 | Box 58 \ 2 Scan012 | |
| Follow-up letter from Lissen Limited regarding the testing of aircraft sparking plugs. | 2nd Dec 1930 | Box 58 \ 2 Scan013 | |
| Letter from Lissen Limited requesting a performance report on aircraft sparking plugs sent for testing. | 16th Dec 1930 | Box 58 \ 2 Scan014 | |
| Article discussing spark plug problems, their relation to heat characteristics, and diagnosing engine conditions. | 16th Mar 1929 | Box 58 \ 2 Scan015 | |
| Detailed explanation of spark plug operation, heat range, and fouling characteristics. | 1st Mar 1931 | Box 58 \ 2 Scan016 | |
| Supplement to a report on detonation, discussing the challenges of obtaining consistent H.U.C.R. values due to fuel deposits. | 1st Mar 1931 | Box 58 \ 2 Scan017 | |
| Letter regarding a new Mica Sparking Plug for aero engines and its performance. | 1st Dec 1931 | Box 58 \ 2 Scan018 | |
| Letter to A.J. Rowledge regarding a spark plug designed by Mr. Roy Hurley and plans for its manufacture in England. | 1st Dec 1931 | Box 58 \ 2 Scan019 | |
| Letter from Captain Cyril Turner regarding a proposition for a new type of mica sparking plug. | 7th Dec 1931 | Box 58 \ 2 Scan020 | |
| Construction and drawbacks of existing mica sparking plugs and proposing an improved H-T plug design. | 7th Dec 1931 | Box 58 \ 2 Scan021 | |
| Letter detailing the features and ongoing tests of a new H-T sparking plug design. | 7th Dec 1931 | Box 58 \ 2 Scan022 | |
| Letter detailing single-cylinder and endurance test results for sparking plugs and their use by other engine manufacturers. | 7th Dec 1931 | Box 58 \ 2 Scan023 | |
| Running time and test parameters for H.T.312 plugs on F.25 and F.607 engine test schedules. | 19th Jan 1932 | Box 58 \ 2 Scan024 | |
| Letter from Captain Cyril Turner concerning Hurley-Townsend Sparking Plugs, requesting a test report and engine specifications. | 2nd Feb 1932 | Box 58 \ 2 Scan025 | |
| From Captain Cyril Turner with requests for tests and engine data. | 23th Feb 1932 | Box 58 \ 2 Scan026 | |
| Test report on B.G. Spark Plugs, type 116, for the Kestrel engine. | 23th Feb 1932 | Box 58 \ 2 Scan027 | |
| Results of engine tests on spark plugs, focusing on fouling, gap erosion, and overall condition. | 23th Feb 1932 | Box 58 \ 2 Scan028 | |
| Three photographic views of a B.G. Paris spark plug. | 24th Feb 1932 | Box 58 \ 2 Scan029 | |
| The testing of Hurley-Townsend sparking plugs, type 312. | 24th Feb 1932 | Box 58 \ 2 Scan030 | |
| Letter to Capt. Cyril Turner regarding tests on Hurley-Townsend Spark Plugs and the service life of existing plugs. | 13th Apr 1932 | Box 58 \ 2 Scan031 | |
| Table of service engine particulars relevant to spark plugs. | 13th Apr 1932 | Box 58 \ 2 Scan032 | |
| The features and test results of Hurley-Townsend Type 312 sparking plugs. | 24th Feb 1932 | Box 58 \ 2 Scan033 | |
| Blueprint detailing scrap sections through the sparking plug bosses for Kestrel and Buzzard engines. | 14th Apr 1932 | Box 58 \ 2 Scan034 | |
| Letter to Capt. Cyril Turner regarding tests on Hurley-Townsend Spark Plugs. | 13th Apr 1932 | Box 58 \ 2 Scan035 | |
| Table of specifications for Kestrel and Buzzard engines relevant to spark plugs. | 13th Apr 1932 | Box 58 \ 2 Scan036 | |
| Blueprint detailing cross-sections of cylinder blocks for Kestrel and Buzzard engines. | 14th Apr 1932 | Box 58 \ 2 Scan037 | |
| Letter from Captain Cyril Turner regarding the testing and potential UK manufacture of Hurley-Townsend spark plugs. | 16th Apr 1932 | Box 58 \ 2 Scan038 | |
| Letter to Capt. Cyril Turner opposing the suggestion of running a Type Test engine on H.T. spark plugs. | 22th Apr 1932 | Box 58 \ 2 Scan039 | |
| Proposing the use of K.L.G. aero plugs alongside Lodge plugs to avoid a monopoly. | 11th May 1932 | Box 58 \ 2 Scan040 | |
| Letter from the Air Ministry granting provisional airworthiness approval for K.L.G. Sparking Plugs, Type V.9. | 15th Feb 1932 | Box 58 \ 2 Scan041 | |
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