| Description | Date | Identifier | |
| Oil consumption tests for the EAC engine, focusing on piston ring modifications. | 1st Mar 1925 | Box 66 \ 1 scan0017 | |
| Piston failure due to high engine speeds and potential design improvements. | 16th Mar 1925 | Box 66 \ 1 scan0018 | |
| Piston ring design to manage wear through unequal surface pressure. | 8th Mar 1925 | Box 66 \ 1 scan0019 | |
| Secret memo discussing drawings for piston modifications, including an experimental reinforced type. | 8th Mar 1925 | Box 66 \ 1 scan0020 | |
| Secret memo proposing to start a 10,000-mile test on car 93-NK with modified die-cast pistons for the EAC 'V' series. | 18th Mar 1925 | Box 66 \ 1 scan0021 | |
| Reducing engine oil consumption and smoke by fitting 'L' shaped piston rings. | 18th Mar 1925 | Box 66 \ 1 scan0022 | |
| Graph of oil consumption curves for an E.A.C. engine, comparing different piston and ring configurations. | 18th Mar 1925 | Box 66 \ 1 scan0023 | |
| Graph comparing oil consumption curves for an E.A.C. engine with different piston and ring setups. | 18th Mar 1925 | Box 66 \ 1 scan0024 | |
| 10,000-mile test for the EAC 'V' Series, concerning piston modifications and vehicle testing. | 18th Mar 1925 | Box 66 \ 1 scan0025 | |
| Secret memo discussing proposed modifications to piston designs. | 18th Mar 1925 | Box 66 \ 1 scan0026 | |
| Secret memorandum with a diagram suggesting a modification to a piston design. | 19th Mar 1925 | Box 66 \ 1 scan0027 | |
| Confirmation of a wire with instructions for modifying a piston for multiple scraper rings. | 20th Mar 1925 | Box 66 \ 1 scan0028 | |
| Confirmation of a wire recommending the inclusion of Piston LEC. 2030 on the next ten thousand units. | 20th Mar 1925 | Box 66 \ 1 scan0029 | |
| Micro-examination and analytical report on a failed E.A.C. Piston. | 20th Mar 1925 | Box 66 \ 1 scan0030 | |
| Alterations to pistons, including ring stops, ring stiffness, and balancing. | 20th Mar 1925 | Box 66 \ 1 scan0031 | |
| Secret memo regarding an improved, strengthened piston with five oil-retaining rings. | 20th Mar 1925 | Box 66 \ 1 scan0032 | |
| Arranging a visit to Derby to inspect car 93-NK with the latest parts, including new pistons. | 1st Mar 1925 | Box 66 \ 1 scan0033 | |
| Authorisation sheet number 1 for the 'V' series regarding consent for a new piston. | 23th Mar 1925 | Box 66 \ 1 scan0034 | |
| Authorisation sheet for a 'V' Series piston modification and 10,000-mile test. | 23th Mar 1925 | Box 66 \ 1 scan0035 | |
| Patent claim for an 'L' section piston oil scraper ring, discussing its function and origin. | 23th Mar 1925 | Box 66 \ 1 scan0036 | |
| Piston design, oil consumption, and potential improvements for piston failures. | 23th Mar 1925 | Box 66 \ 1 scan0037 | |
| 'EAC' engine overoiling issues, comparing them with 40/50 and 20 HP models. | 1st Feb 1925 | Box 66 \ 1 scan0038 | |
| Piston ring performance, oil consumption, and scraper ring design. | 25th Mar 1925 | Box 66 \ 1 scan0039 | |
| Adjustments to engine oil pressure and oil consumption test results. | 25th Mar 1925 | Box 66 \ 1 scan0040 | |
| Secret memo discussing various design suggestions for scraper rings and pistons. | 31th Mar 1925 | Box 66 \ 1 scan0041 | |
| Design of pistons, specifically scraper rings and piston pin size and fit. | 31th Mar 1925 | Box 66 \ 1 scan0042 | |
| 'V' Series engine oil consumption, comparing the performance of new pistons against original designs and different oiling methods. | 1st Apr 1925 | Box 66 \ 1 scan0043 | |
| Confirming production status and component suitability for 'V' Series Pistons. | 2nd Apr 1925 | Box 66 \ 1 scan0044 | |
| Piston design approval following satisfactory oil consumption reports from France. | 3rd Apr 1925 | Box 66 \ 1 scan0045 | |
| Secret memo regarding the design and testing of a double ring piston. | 4th Apr 1925 | Box 66 \ 1 scan0046 | |
| Experimental, grooved piston ring stop suggested by Mr. Royce. | 8th Apr 1925 | Box 66 \ 1 scan0047 | |
| 'V' series engine oil consumption, detailing tests with baffles and different piston ring configurations. | 8th Apr 1925 | Box 66 \ 1 scan0048 | |
| The performance of 'L' shaped rings and their relation to engine oil consumption. | 25th Sep 1924 | Box 66 \ 1 scan0049 | |
| 'V' series pistons, detailing ring failures and oil consumption tests. | 15th Apr 1925 | Box 66 \ 1 scan0050 | |
| Piston ring design and its effect on oil consumption. | 15th Apr 1925 | Box 66 \ 1 scan0051 | |
| Comparing different piston and ring configurations, focusing on oil consumption and performance. | 1st Apr 1925 | Box 66 \ 1 scan0052 | |
| Experiments on piston designs and oil control methods. | 28th Apr 1925 | Box 66 \ 1 scan0053 | |
| Alteration of a conical top piston to incorporate a lower scraper ring for testing purposes. | 29th Apr 1925 | Box 66 \ 1 scan0054 | |
| Extract detailing proposed design changes to address excess oil consumption. | 29th Apr 1925 | Box 66 \ 1 scan0055 | |
| Extension of production for pistons and fabric couplings for the 'V' Series Chassis. | 30th Apr 1925 | Box 66 \ 1 scan0056 | |
| Oil consumption tests for 'V' series and Condor engine 'L' shaped piston rings. | 1st May 1925 | Box 66 \ 1 scan0057 | |
| The manufacture of 'V' Series Pistons, proposing an order for 100 more sets and considering an alternative to knurling. | 8th May 1925 | Box 66 \ 1 scan0058 | |
| Oil consumption issues related to 'L' shaped piston rings and the effects of lapping. | 13th May 1925 | Box 66 \ 1 scan0059 | |
| Production of 'V' Series pistons (E.73376) for the last 100 chassis. | 27th May 1925 | Box 66 \ 1 scan0060 | |
| The testing of magnesium pistons, detailing weight savings and cracking issues. | 12th Jun 1925 | Box 66 \ 1 scan0061 | |
| The investigation of 'knocks' on the Phantom chassis. | 1st Oct 1925 | Box 66 \ 1 scan0062 | |
| The investigation of piston knocks. | 12th Jun 1925 | Box 66 \ 1 scan0063 | |
| The causes of engine knock related to piston fit, oil film, and piston design. | 12th Jun 1925 | Box 66 \ 1 scan0064 | |
| Piston clearance, slap, and skirt flexibility. | 12th Jun 1925 | Box 66 \ 1 scan0065 | |
| Piston troubles discovered on the 'Phantom' model during test bench conditions. | 12th Oct 1925 | Box 66 \ 1 scan0066 | |
| Piston knocks, confirming the theory that a flexible skirt is required for silent operation. | 12th Jun 1925 | Box 66 \ 1 scan0067 | |
| The performance of standard pistons modified with a split skirt. | 12th Jun 1925 | Box 66 \ 1 scan0068 | |
| Piston modifications to improve flexibility and reduce knocking. | 12th Jun 1925 | Box 66 \ 1 scan0069 | |
| And comparing various piston designs, including a patented design with inclined stays. | 12th Jun 1925 | Box 66 \ 1 scan0070 | |
| Piston design, discussing gudgeon pins and composite materials. | 12th Jun 1925 | Box 66 \ 1 scan0071 | |
| Various solutions to resolve piston knock trouble in the Phantom engine. | 15th Oct 1925 | Box 66 \ 1 scan0072 | |
| Awaiting the results of piston modifications to prevent knocking and piston pin difficulties. | 18th Nov 1925 | Box 66 \ 1 scan0073 | |
| The production and testing of new die-cast pistons for the Phantom model. | 21th Oct 1925 | Box 66 \ 1 scan0074 | |
| Production approval for a 40/50HP Chassis Die Casting Piston E.73376. | 9th Dec 1925 | Box 66 \ 1 scan0075 | |
| The satisfactory testing of die-cast pistons to replace sand-cast pistons for the Phantom engine. | 11th Dec 1925 | Box 66 \ 1 scan0076 | |
| Oiling tests conducted on the Phantom model. | 1st Dec 1925 | Box 66 \ 1 scan0077 | |
| Oil feed experiments for the Phantom and Silver Ghost models to address over-oiling. | 12th Jun 1925 | Box 66 \ 1 scan0078 | |
| With graphs showing oil consumption on the Silver Ghost model versus oil pressure and oil flow rates. | 12th Aug 1925 | Box 66 \ 1 scan0079 | |
| Oil feed arrangements and their effect on oil leakage and consumption in main bearings. | 12th Jun 1925 | Box 66 \ 1 scan0080 | |
| Oil discharge in a Phantom engine comparing intermediate bearings with and without grooves. | 12th Jun 1925 | Box 66 \ 1 scan0081 | |
| Summarizing the factors that control engine oil consumption. | 12th Jun 1925 | Box 66 \ 1 scan0082 | |
| Reducing engine over-oiling through piston modifications and lubrication system design. | 12th Jun 1925 | Box 66 \ 1 scan0083 | |
| Endurance test of 'pedestal' type pistons for a Phantom engine, investigating fractures and 'piston knocks'. | 1st Apr 1926 | Box 66 \ 1 scan0084 | |
| Comparison between a standard pattern piston and a pedestal piston, discussing clearance, expansion and performance under load. | 1st Apr 1926 | Box 66 \ 1 scan0085 | |
| Comparison of mechanical efficiency and an investigation into piston knocks for pedestal pistons versus standard pistons. | 1st Apr 1926 | Box 66 \ 1 scan0086 | |
| Three experiments conducted to investigate and reduce engine knock. | 1st Apr 1926 | Box 66 \ 1 scan0087 | |
| Methods to eliminate engine knock by reinforcing the cylinder skirt with a steel sleeve. | 5th Oct 1925 | Box 66 \ 1 scan0088 | |
| Engine testing, focusing on cylinder skirt deflection and piston knocks. | 5th Oct 1925 | Box 66 \ 1 scan0089 | |
| Piston design theory, piston knock, and the failure of pedestal pistons during endurance testing. | 5th Oct 1925 | Box 66 \ 1 scan0090 | |
| Piston knock issues and potential solutions involving cylinder skirts. | 22th Apr 1926 | Box 66 \ 1 scan0091 | |
| Failure of a pedestal piston and proposing three ways to strengthen the design. | 22th Apr 1926 | Box 66 \ 1 scan0092 | |
| Modifications to the Phantom chassis, including steering, ignition, and pistons. | 18th May 1926 | Box 66 \ 1 scan0093 | |
| Design and experimental testing of three new piston types. | 18th May 1926 | Box 66 \ 1 scan0094 | |
| Different designs for Phantom engine pistons, with a requirement from Mr. Royce. | 19th May 1926 | Box 66 \ 1 scan0095 | |
| Engine 7-EX's performance after 8,600 miles, focusing on issues with exhaust firing, self-ignition, and carbon build-up. | 6th Apr 1926 | Box 66 \ 1 scan0096 | |
| Use of magnesium casting and Y-metal for crankcases and pistons. | 1st Jul 1926 | Box 66 \ 1 scan0097 | |
| Urgent need for magnesium copper and Y-alloy pistons, preferring cross-web designs over Zephyr types. | 7th Jul 1926 | Box 66 \ 1 scan0098 | |
| New spring ring device and other modifications for piston pins on various engines. | 1st Aug 1926 | Box 66 \ 1 scan0099 | |
| Test report on the performance of pedestal pistons, detailing a 32-hour run and discussing issues with piston knock. | 30th Aug 1926 | Box 66 \ 1 scan0100 | |
| Weight comparison between standard and pedestal pistons and a report on their operational testing. | 3rd Sep 1926 | Box 66 \ 1 scan0101 | |
| Manufacturing methods for special light pistons for the Phantom model, weighing sand casting against forging. | 3rd Sep 1926 | Box 66 \ 1 scan0102 | |
| Modifications to a Phantom pedestal piston made from forged magnesium. | 16th Sep 1926 | Box 66 \ 1 scan0103 | |
| Confirming Mr. Royce's agreement to use nickel steel for bolts in a pedestal-type piston. | 4th Oct 1926 | Box 66 \ 1 scan0104 | |
| Causes of gummed up piston rings, comparing issues found with aluminium versus cast iron pistons. | 6th Oct 1926 | Box 66 \ 1 scan0105 | |
| The causes of gummed-up piston rings, attributing it to gas leakage, and the development of an apparatus to measure it. | 6th Oct 1926 | Box 66 \ 1 scan0106 | |
| Modifying an apparatus for engine leakage tests and referencing a 1926 report on piston temperatures. | 11th Oct 1926 | Box 66 \ 1 scan0107 | |
| Causes of gumming pistons, comparing different lubricating oils, and suggesting testing methods. | 11th Oct 1926 | Box 66 \ 1 scan0108 | |
| Diagrams and charts detailing piston temperature analysis and a comparison between aluminum and cast iron pistons. | 12th Oct 1926 | Box 66 \ 1 scan0109 | |
| Tests for gas leakage past pistons and the apparatus devised to measure it. | 12th Oct 1926 | Box 66 \ 1 scan0110 | |
| Test report on engine air leakage measurement methods and results against varying RPM for a standard Phantom engine. | 12th Oct 1926 | Box 66 \ 1 scan0111 | |
| Engine leakage tests, noting variations and planning for improved testing methods. | 12th Oct 1926 | Box 66 \ 1 scan0112 | |
| Test report on the relative flexibility of pedestal pistons compared to the standard design. | 12th Oct 1926 | Box 66 \ 1 scan0113 | |
| Technical report on piston flexibility tests, including a blueprint diagram, a table of results, and analysis. | 14th Oct 1926 | Box 66 \ 1 scan0114 | |
| Piston leakage and proposing a change in testing methodology from various speeds to various pressures. | 14th Oct 1926 | Box 66 \ 1 scan0115 | |
| Tests to determine gas leakage past the pistons on a Phantom engine with various pressures. | 9th Nov 1926 | Box 66 \ 1 scan0116 | |
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