| Description | Date | Identifier | |
| Fitting new type aluminium pistons for the X.2638 40/50 HP chassis, focusing on gudgeon pin issues. | 8th Feb 1919 | Box 35 \ 2 scan 050 | |
| Potential issues of gudgeon pins turning within aluminium piston recesses. | 8th Feb 1919 | Box 35 \ 2 scan 051 | |
| Mr. Royce's remarks on various 40/50 HP chassis piston designs. | 25th Feb 1919 | Box 35 \ 2 scan 052 | |
| Technical memo discussing engine compression ratios, piston materials, and detonations for the 40/50 chassis. | 18th Feb 1919 | Box 35 \ 2 scan 053 | |
| Modifications and tests on carburetter and camshaft for the 7 CA model, including issues with petrol quality. | 18th Feb 1919 | Box 35 \ 2 scan 054 | |
| Mr. Royce's remarks on various 40/50 HP chassis piston designs. | 25th Feb 1919 | Box 35 \ 2 scan 055 | |
| Design points for a 40/50 HP chassis die-cast piston with high and low piston pins. | 6th Mar 1919 | Box 35 \ 2 scan 056 | |
| Design amendments for pistons and requesting a revised blueprint. | 25th Oct 1918 | Box 35 \ 2 scan 057 | |
| Design modifications for connecting rods on a 40/50 chassis. | 6th Mar 1918 | Box 35 \ 2 scan 058 | |
| Tests of aluminium pistons for the 40/50 Chassis X.3400 regarding engine knock issues. | 25th Mar 1919 | Box 35 \ 2 scan 059 | |
| The successful testing of short connecting rods on the 40/50 chassis. | 31th Mar 1919 | Box 35 \ 2 scan 060 | |
| Recommendation to standardise the short connecting rods for the 40/50 chassis. | 7th Apr 1919 | Box 35 \ 2 scan 061 | |
| Standardisation document for short connecting rods for the 40/50 chassis, to eliminate piston knocks. | 9th Apr 1919 | Box 35 \ 2 scan 062 | |
| Continued discussion on managing customer complaints regarding piston knocks. | 7th Apr 1919 | Box 35 \ 2 scan 063 | |
| Test report on short connecting rods (X.3400) after successful bench and road tests. | 17th Nov 1919 | Box 35 \ 2 scan 064 | |
| New piston design for the 40/50 chassis, noting differences from tested versions and advising caution before machining. | 9th Apr 1919 | Box 35 \ 2 scan 065 | |
| Standardisation proposal for a short connecting rod for the 40/50 Chassis. | 9th Apr 1919 | Box 35 \ 2 scan 066 | |
| Continued discussion on customer complaints regarding knocks from the cast-iron piston. | 7th Apr 1919 | Box 35 \ 2 scan 067 | |
| Test report on short connecting rods after a 100-hour bench test and a 10,000-mile road test. | 17th Nov 1919 | Box 35 \ 2 scan 068 | |
| Instruction to halt the machining of chassis pistons pending a report on recent modifications. | 11th Apr 1919 | Box 35 \ 2 scan 069 | |
| Requesting the modification of chassis pistons E.17764 and 17792 by removing material from the crown. | 29th Apr 1919 | Box 35 \ 2 scan 070 | |
| Instructing to proceed with casting 100 sets of altered chassis pistons, but to hold grinding pending sizes from the Experimental Department. | 1st May 1919 | Box 35 \ 2 scan 071 | |
| New piston design defects, including a thick skirt and long ring pins, with modifications suggested by Mr. Hives and Mr. Royce. | 1st May 1919 | Box 35 \ 2 scan 072 | |
| Request for a sample cylinder to investigate a complaint about the length of the piston ring stop. | 1st May 1919 | Box 35 \ 2 scan 073 | |
| Modification of 40/50 HP chassis pistons with concave crowns to minimise piston knock. | 5th May 1919 | Box 35 \ 2 scan 074 | |
| With a diagram detailing recommended clearances for chassis pistons. | 19th May 1919 | Box 35 \ 2 scan 075 | |
| Testing policy and the standardization of a short connecting rod for the 40/50 HP chassis. | 31th May 1919 | Box 35 \ 2 scan 076 | |
| 10,000-mile standard test, chassis shortages for testing, and proposing flexibility in mileage for Mr. Royce and his staff. | 31th May 1919 | Box 35 \ 2 scan 077 | |
| Mileage of short connecting rods on chassis 49-GB and 1.E.X. | 7th Jun 1919 | Box 35 \ 2 scan 078 | |
| The urgent need for a satisfactory aluminium piston design for repair cars. | 9th Jun 1919 | Box 35 \ 2 scan 079 | |
| Completing a 10,000-mile test on Short Connecting Rods to get a Standardization Sheet signed. | 13th Jun 1919 | Box 35 \ 2 scan 080 | |
| Recommending a modification for aluminium pistons on the 40/50 chassis due to bearing issues around the gudgeon pin hole. | 21th Jun 1919 | Box 35 \ 2 scan 081 | |
| Suggestion to proceed with machining aluminium pistons for the 40/50 chassis. | 23th Jun 1919 | Box 35 \ 2 scan 082 | |
| Expansion and necessary clearances for aluminium and cast iron pistons. | 27th Jun 1919 | Box 35 \ 2 scan 083 | |
| Hand-drawn sketch showing dimensional measurements in inches for a component. | 25th Oct 1918 | Box 35 \ 2 scan 084 | |
| Heat expansion test results for Cast Iron and Aluminium pistons. | 27th Jun 1919 | Box 35 \ 2 scan 085 | |
| Piston expansion, favouring aluminium pistons and requesting calculations on the risks of tight pistons. | 27th Jun 1919 | Box 35 \ 2 scan 086 | |
| To halt the grinding of aluminium pistons for the 40/50 chassis due to unsatisfactory clearances. | 11th Aug 1919 | Box 35 \ 2 scan 087 | |
| Arrangements for testing cylinders and pistons for Paris Show Cars and production chassis. | 15th Aug 1919 | Box 35 \ 2 scan 088 | |
| Road test report on chassis 1.EX detailing engine performance, overheating issues, and a seized piston. | 28th Jul 1919 | Box 35 \ 2 scan 089 | |
| To halt the grinding of aluminium pistons for the 40/50 chassis due to unsatisfactory clearances. | 11th Aug 1919 | Box 35 \ 2 scan 090 | |
| Engine knocking issues with aluminium pistons on standard production cars. | 18th Aug 1919 | Box 35 \ 2 scan 091 | |
| Agreeing that production chassis can be delivered with piston knocks, providing they are not manifest below 50°C, and requesting standard piston clearance details. | 19th Aug 1919 | Box 35 \ 2 scan 092 | |
| Sketch detailing satisfactory piston clearances for the 40/50 chassis. | 19th Aug 1919 | Box 35 \ 2 scan 093 | |
| The production strategy for aluminium pistons for the 40/50 chassis. | 20th Aug 1919 | Box 35 \ 2 scan 094 | |
| Improvements for Car 1 EX, focusing on piston knocking and lubricating oil issues. | 21th Aug 1919 | Box 35 \ 2 scan 095 | |
| From R to EH discussing solutions for piston knocks through improved lubrication systems. | 21th Aug 1919 | Box 35 \ 2 scan 096 | |
| Engine piston compression, lubrication performance, and running characteristics. | 21th Mar 1919 | Box 35 \ 2 scan 097 | |
| Standards for piston knocks and the challenges with piston clearances on different vehicle models. | 22th Aug 1919 | Box 35 \ 2 scan 098 | |
| Piston knock issues with aluminium pistons and the resulting customer policy. | 22th Aug 1919 | Box 35 \ 2 scan 099 | |
| Ongoing work to cure piston knocks and the plan to fit new pistons to car 49-GB. | 25th Aug 1919 | Box 35 \ 2 scan 100 | |
| Explaining how to reduce piston knocks in a cold engine by using late ignition. | 25th Aug 1919 | Box 35 \ 2 scan 101 | |
| Instruction to limit stock levels of standard and high compression piston castings due to imminent design changes. | 26th Aug 1919 | Box 35 \ 2 scan 102 | |
| Design rationale for piston ring placement on 40/50 HP engines to reduce knocking. | 1st Aug 1919 | Box 35 \ 2 scan 103 | |
| Extract listing new parts, including shorter connecting rods, for the 40/50 chassis. | 27th Aug 1919 | Box 35 \ 2 scan 104 | |
| List of new parts fitted to the 40/50 chassis compared to the pre-war version, specifically mentioning Aluminium Pistons. | 27th Aug 1919 | Box 35 \ 2 scan 105 | |
| Standard allowances for fitting pistons to prevent piston knocks. | 27th Aug 1919 | Box 35 \ 2 scan 106 | |
| Advantages of pistons with low-down rings. | 1st Aug 1919 | Box 35 \ 2 scan 107 | |
| Proposal to test extra cylinder lubrication to address piston knock under light load. | 1st Aug 1919 | Box 35 \ 2 scan 108 | |
| Query regarding modifications to the grinding size of chassis pistons. | 29th Aug 1919 | Box 35 \ 2 scan 109 | |
| Investigation into the causes of piston knocks, identifying alignment and lubrication as the primary factors. | 29th Aug 1919 | Box 35 \ 2 scan 110 | |
| Piston knocking issues and the practice of intentionally tilting pistons to resolve them. | 29th Aug 1919 | Box 35 \ 2 scan 111 | |
| Investigation into methods for overcoming engine knocks, including piston modifications and different alloys. | 29th Aug 1919 | Box 35 \ 2 scan 112 | |
| Experiments with piston designs, clearances, and lubrication oils to reduce engine knocking. | 1st Aug 1919 | Box 35 \ 2 scan 113 | |
| Investigation into the causes and potential mechanical solutions for engine piston knocks. | 29th Aug 1919 | Box 35 \ 2 scan 114 | |
| Progress on resolving piston knock issues, focusing on lubrication with castor oil. | 1st Sep 1919 | Box 35 \ 2 scan 115 | |
| Running an engine on a single charge of oil and improving the crankcase draining process. | 19th May 1919 | Box 35 \ 2 scan 116 | |
| Conflict between performance and silence, specifically regarding knocking from aluminium pistons and suggesting a switch to cast iron. | 2nd Sep 1919 | Box 35 \ 2 scan 117 | |
| Letter from 'CJ' arguing against using aluminium pistons due to a knocking issue, advocating for cast iron pistons instead. | 9th Sep 1919 | Box 35 \ 2 scan 118 | |
| Recommendation of Castrol oil for engines to reduce piston knocks and wear. | 9th Sep 1919 | Box 35 \ 2 scan 119 | |
| Policy on pistons, engine silence, and reliability versus the issue of piston knocks. | 5th Sep 1919 | Box 35 \ 2 scan 120 | |
| Technical memorandum discussing the issue of piston knocking, comparing cast iron and aluminium pistons, and outlining causes and potential cures. | 1st Sep 1919 | Box 35 \ 2 scan 121 | |
| Piston knock, its causes, potential cures by misaligning the connecting rod, and the suggestion to educate drivers. | 5th Sep 1919 | Box 35 \ 2 scan 122 | |
| Preventing piston knock by improving lubrication and suggesting the use of Castrol oil. | 5th Sep 1919 | Box 35 \ 2 scan 123 | |
| Reducing engine wear and piston knock, including fitting a thermostat and considering future modifications. | 1st Sep 1919 | Box 35 \ 2 scan 124 | |
| Experiments investigating the cause of piston knocks in test cars. | 20th Sep 1919 | Box 35 \ 2 scan 125 | |
| Gudgeon pin alignment measurements and an oiling test on an experimental engine. | 20th Sep 1919 | Box 35 \ 2 scan 126 | |
| Experiments to cure piston knock and over-oiling issues in an engine. | 20th Sep 1919 | Box 35 \ 2 scan 127 | |
| Connecting rod deflection tests and an analysis of engine knock sounds. | 20th Sep 1919 | Box 35 \ 2 scan 128 | |
| Piston design experiments to eliminate engine knocking. | 20th Sep 1919 | Box 35 \ 2 scan 129 | |
| Satisfactory results of running long pistons to address piston knocks. | 22th Sep 1919 | Box 35 \ 2 scan 130 | |
| Insulation for lamp connection wiring and potential causes for leaky pistons. | 22th Sep 1919 | Box 35 \ 2 scan 131 | |
| Issues with chassis 49 GB, covering the engine, pistons, magneto drive, clutch, and dynamo. | 22th Sep 1919 | Box 35 \ 2 scan 132 | |
| Vehicle component issues including battery electrolyte loss, rear shock absorbers, Castrol lubrication, and cylinder lubrication. | 22th Sep 1919 | Box 35 \ 2 scan 133 | |
| Modifications to piston design, including increasing skirt length and experimenting with spring pressure. | 24th Sep 1919 | Box 35 \ 2 scan 134 | |
| Issues with aluminium pistons seizing during dynamometer tests due to reduced clearance. | 25th Sep 1919 | Box 35 \ 2 scan 135 | |
| Fitting of aluminium pistons, pre-war practices for piston knocks, and matching procedures. | 26th Sep 1919 | Box 35 \ 2 scan 136 | |
| Acute position and supply issues regarding aluminium pistons. | 30th Sep 1919 | Box 35 \ 2 scan 137 | |
| Challenges of fitting aluminium pistons, balancing piston knock against the risk of seizing. | 30th Sep 1919 | Box 35 \ 2 scan 138 | |
| Ongoing issues and policy disputes regarding aluminium piston knocks. | 30th Sep 1919 | Box 35 \ 2 scan 139 | |
| Typed document fragment urging for strong efforts to be made for a satisfactory settlement. | 30th Sep 1919 | Box 35 \ 2 scan 140 | |
| Difficulty in obtaining aluminium pistons that meet the required specifications. | 30th Sep 1919 | Box 35 \ 2 scan 141 | |
| The challenges of fitting aluminium pistons, focusing on the trade-off between piston knock and seizure. | 26th Sep 1919 | Box 35 \ 2 scan 142 | |
| To stop all work on pistons E.18135/6 for the 40/50 chassis as they are no improvement. | 6th Oct 1919 | Box 35 \ 2 scan 143 | |
| Recommendations for the standard practice of fitting aluminium pistons. | 8th Oct 1919 | Box 35 \ 2 scan 144 | |
| Instructions for checking piston clearances and performing easing to prevent engine seizing. | 8th Oct 1919 | Box 35 \ 2 scan 145 | |
| Experimental work on engine pistons to avoid knocks or seizing. | 7th Oct 1919 | Box 35 \ 2 scan 146 | |
| Notice confirming that Die Cast Aluminium Pistons are now standard. | 7th Oct 1919 | Box 35 \ 2 scan 147 | |
| Recommendation to modify the piston locking screw design for the 40/50 chassis to prevent distortion. | 8th Oct 1919 | Box 35 \ 2 scan 148 | |
| Experiments to reduce piston knocks using an oil-damped cylinder versus a spring. | 9th Oct 1919 | Box 35 \ 2 scan 149 | |
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