| Description | Date | Identifier | |
| Responding to an inquiry regarding the stock of 20/25 HP wheels and tyres. | 11th Nov 1935 | Box 106 \ 4 scan0149 | |
| Progress report on the Goshawk's 4-speed side lever servo drive and gearbox design. | 27th Jun 1924 | Box 106 \ 5 scan0001 | |
| Excessive tappet roller wear on test engines, attributed to oil shortage, and recommending pre-lubrication procedures. | 28th Jan 1926 | Box 106 \ 5 scan0002 | |
| Engine improvements for the E.16, F.10, Phantom, and Goshawk models, focusing on valve restrictions and new components. | 30th Mar 1926 | Box 106 \ 5 scan0003 | |
| Investigation into valve seat erosion caused by valve rotation during engine over-run. | 8th Aug 1926 | Box 106 \ 5 scan0004 | |
| Causes and solutions for noisy tappets on Phantom and 20 HP cars. | 1st Apr 1927 | Box 106 \ 5 scan0005 | |
| Schematic drawing for raised valve rockers for a 20 HP engine. | 11th Apr 1927 | Box 106 \ 5 scan0006 | |
| Proposed modification to the valve rocker mechanism to reduce noise and wear. | 22th Apr 1927 | Box 106 \ 5 scan0007 | |
| Modified 20 HP cylinder head with large diameter valves. | 30th May 1927 | Box 106 \ 5 scan0008 | |
| New 20 HP low stress valve spring for experimental testing and standardization. | 20th Jul 1927 | Box 106 \ 5 scan0009 | |
| Request to obtain 30 stronger valve springs for a 20 HP model, with detailed specifications. | 1st Aug 1927 | Box 106 \ 5 scan0010 | |
| Recommending longer inlet cams and new low-stress valve springs for various aero engines. | 13th Aug 1927 | Box 106 \ 5 scan0011 | |
| Broken valve spring on a new 20-HP car and its similarity to issues with Condor valve springs. | 21th Sep 1927 | Box 106 \ 5 scan0012 | |
| Forceful memo demanding the immediate cessation of production of doubtful valve springs and the urgent testing of new designs and materials. | 16th Nov 1927 | Box 106 \ 5 scan0013 | |
| Querying the purpose of a small screw on the 20 HP valve gear. | 23th Feb 1928 | Box 106 \ 5 scan0014 | |
| Valve sizes for EAC.10 & India 3, referencing document LeC.2523. | 6th Mar 1928 | Box 106 \ 5 scan0015 | |
| And comparing valve sizes for various engine models. | 6th Mar 1928 | Box 106 \ 5 scan0016 | |
| Agreeing on valve sizes and materials for the 20 HP and Phantom models. | 9th Mar 1928 | Box 106 \ 5 scan0017 | |
| Geometry of valve gear rockers on the Phantom and 20 HP models to reduce noise. | 13th Mar 1928 | Box 106 \ 5 scan0018 | |
| Modified rocker angle for the Sports Phantom engine, including a diagram of eccentric thrust. | 15th Mar 1928 | Box 106 \ 5 scan0019 | |
| Proposals for modifying the 20 HP cylinder for the India Chassis, detailing four different options. | 15th Mar 1928 | Box 106 \ 5 scan0020 | |
| Modifications to 20HP valve fittings to improve oil supply to the tappets and prevent knocks. | 2nd Apr 1928 | Box 106 \ 5 scan0021 | |
| New relief valve design for the 20 HP valve tappet and rocker shaft lubrication system. | 18th Apr 1928 | Box 106 \ 5 scan0022 | |
| Lubrication issues with the valve tappet and rocker shaft on the 20 HP engine, particularly during cold starts. | 18th Apr 1928 | Box 106 \ 5 scan0023 | |
| Oil flow issues and recommending fitting the Phantom three-stage release valve to the new India engine. | 25th Apr 1928 | Box 106 \ 5 scan0024 | |
| Recommending an immediate change to the lubrication method for 20 HP valve tappets, and requesting a new design for a 3-stage relief valve. | 25th Apr 1928 | Box 106 \ 5 scan0025 | |
| From 'R.' suggesting a method for testing different types of valve steels. | 11th Jun 1928 | Box 106 \ 5 scan0026 | |
| Implementing valve guide clearance improvements from the Phantom model on the 20 HP model. | 12th Jun 1928 | Box 106 \ 5 scan0027 | |
| Sending a drawing for the India 3 Cylinder Head and Valve Rockers. | 23th Jun 1928 | Box 106 \ 5 scan0028 | |
| Drawing LeC. 2565 for an India 3 tappet rod. | 1st Jun 1928 | Box 106 \ 5 scan0029 | |
| The design of new cam forms for various car and aero engines. | 6th Oct 1928 | Box 106 \ 5 scan0030 | |
| Note on valve clearances and cylinder gaskets, detailing issues from gasket settling and best practices for reuse. | 10th Oct 1928 | Box 106 \ 5 scan0031 | |
| Engine valve sticking issues on model 12-G-4 due to insufficient oil. | 16th Oct 1928 | Box 106 \ 5 scan0032 | |
| Sticking valve inlets on the 20 HP engine and Phantom power curves. | 17th Oct 1928 | Box 106 \ 5 scan0033 | |
| Engine experiments concerning camshafts, piston rings, and torque reaction. | 17th Oct 1928 | Box 106 \ 5 scan0034 | |
| Coupling ratings and details of a Chrysler spring drive. | 19th Oct 1928 | Box 106 \ 5 scan0035 | |
| Oil supply for valves and clutch shudder issues on Phantom and 20 HP cars. | 19th Oct 1928 | Box 106 \ 5 scan0036 | |
| Clutch judder issue and special valve guide clearances on a 20 HP vehicle. | 22th Oct 1928 | Box 106 \ 5 scan0037 | |
| Discussion about one-stage and three-stage relief valves and their effect on oiling for 20 HP and Phantom engines. | 29th Oct 1928 | Box 106 \ 5 scan0038 | |
| 20 HP valve clearances, gasket settling, reuse, and lubrication. | 29th Oct 1928 | Box 106 \ 5 scan0039 | |
| Modified oiling scheme for 20 HP tappets to address issues of wear and noise. | 28th Nov 1928 | Box 106 \ 5 scan0040 | |
| Instructions for fitting new cylinder head gaskets and testing on 20-HP valves. | 5th Nov 1928 | Box 106 \ 5 scan0041 | |
| Standardisation of a scheme and parts availability for a 20 HP Chassis GSK-55. | 6th Nov 1928 | Box 106 \ 5 scan0042 | |
| Design of new taper valve springs and camshafts for the 20 HP engine to prevent breakage and increase speed. | 10th Nov 1928 | Box 106 \ 5 scan0043 | |
| Secret internal memo containing a telegram regarding improvements to a 20 HP car, specifically mentioning rollerless tappets. | 26th Apr 1929 | Box 106 \ 5 scan0044 | |
| Revised 20 HP valve timing following Mr. Royce's wishes. | 18th Jun 1929 | Box 106 \ 5 scan0045 | |
| Issues with modified open-ended valve springs on 20 HP and Phantom cars, recommending a return to the previous design due to valve noise. | 16th Dec 1929 | Box 106 \ 5 scan0046 | |
| Implementation of asbestos valve washers and an increased gland angle to address an over-oiling problem in the 20 HP car. | 18th Mar 1930 | Box 106 \ 5 scan0047 | |
| Directive on rectifying over-oiling at low speeds by replacing standard felt washers with new asbestos washers and guides. | 30th Aug 1930 | Box 106 \ 5 scan0048 | |
| Instruction to minimize the stock of valve guides and ensure future manufacturing accommodates asbestos valve washers. | 30th Aug 1930 | Box 106 \ 5 scan0049 | |
| Standardisation of asbestos valve guide washers on the 20 HP chassis. | 1st Sep 1930 | Box 106 \ 5 scan0050 | |
| Laboratory report on a failed 20/25 HP valve spring, attributing the failure to overstressing. | 3rd Jul 1931 | Box 106 \ 5 scan0051 | |
| Instruction memo detailing altered blueprints and replacement parts for the 20/25 HP Chassis valves and fittings, specifically for a Cast Iron Turbulent Head with increased valve lift. | 14th Jul 1931 | Box 106 \ 5 scan0052 | |
| Requesting further sets of valve springs for 25 HP C.I. and IV.G.6 units. | 23th Oct 1931 | Box 106 \ 5 scan0053 | |
| Standardization of valve springs and a higher lift camshaft for the 25HP engine. | 24th Nov 1931 | Box 106 \ 5 scan0054 | |
| Comparison of standard production (E.56325) and proposed production (Hs.451) valve springs. | 24th Nov 1931 | Box 106 \ 5 scan0055 | |
| Blueprint showing designs and modifications for inlet and exhaust valves with various measurements. | 28th Nov 1931 | Box 106 \ 5 scan0056 | |
| Comparison graph of load, stress, and deflection for 25 HP chassis valve springs. | 28th Nov 1931 | Box 106 \ 5 scan0057 | |
| Performance and standardization of 25 HP valve springs. | 28th Nov 1931 | Box 106 \ 5 scan0058 | |
| Details and stress calculations for a 25 HP valve spring. | 28th Nov 1931 | Box 106 \ 5 scan0059 | |
| Technical drawing of a 'China' valve spring. | 28th Nov 1931 | Box 106 \ 5 scan0060 | |
| Standardisation of chassis parts, specifically valve springs, washers, and guides. | 7th Jan 1932 | Box 106 \ 5 scan0061 | |
| Standardisation form detailing the fitting of a new part to a specific chassis. | 12th Mar 1932 | Box 106 \ 5 scan0062 | |
| Test report on valve spring performance and measurements during endurance runs. | 12th Jul 1932 | Box 106 \ 5 scan0063 | |
| Endurance tests on valve springs for the 20/25 HP engine, concluding they are unsuitable for standardisation. | 5th Jul 1932 | Box 106 \ 5 scan0064 | |
| Use of specific valve springs and their effect on performance and timing gear rattle. | 19th Jul 1932 | Box 106 \ 5 scan0065 | |
| The performance of Valve Springs (HS.477/E58525) for the 20/25HP model. | 31th Aug 1932 | Box 106 \ 5 scan0066 | |
| Technical report on the development and issues with self-adjusting tappets on the J.3 unit. | 12th Sep 1932 | Box 106 \ 5 scan0067 | |
| Comparison of plunger and casing designs between R.R. and Cadillac, analysing leakage factors. | 12th Sep 1932 | Box 106 \ 5 scan0068 | |
| Comparison of plungers and springs between Cadillac and R.R, focusing on leakage factor. | 12th Sep 1932 | Box 106 \ 5 scan0069 | |
| Comparison document detailing the specifications for plungers and springs for R.R. and Cadillac models. | 23th Sep 1932 | Box 106 \ 5 scan0070 | |
| Two experimental schemes for modified plungers for automatic tappets. | 23th Sep 1932 | Box 106 \ 5 scan0071 | |
| Report on self-adjusting tappets and the return of defective plungers and valves for testing. | 27th Oct 1932 | Box 106 \ 5 scan0072 | |
| Troubleshooting leaking plunger valves on self-adjusting tappets. | 27th Oct 1932 | Box 106 \ 5 scan0073 | |
| Provision of Exhaust and Inlet Valve Lift Curves. | 27th Oct 1932 | Box 106 \ 5 scan0074 | |
| The status of the J.2 engine, specifically concerning tappets, springs, and bore liners. | 8th Nov 1932 | Box 106 \ 5 scan0075 | |
| New Inlet and Exhaust Valve Curves, which supersede a previous version. | 28th Nov 1932 | Box 106 \ 5 scan0076 | |
| Proposed modifications to self-adjusting tappets for the J.2 unit. | 30th Nov 1932 | Box 106 \ 5 scan0077 | |
| The failure of cast iron eccentric rockers on a self-adjusting tappet and a proposal to remake them in steel. | 12th Dec 1932 | Box 106 \ 5 scan0078 | |
| Blueprint for an improved exhaust valve to replace an existing one for Japan I units. | 21th Dec 1932 | Box 106 \ 5 scan0079 | |
| Material issues and the production of silent tappets for the J.III unit. | 3rd Mar 1933 | Box 106 \ 5 scan0080 | |
| Tests conducted on a silent tappet rocker system with a hard shaft and nickel eccentrics. | 7th Mar 1933 | Box 106 \ 5 scan0081 | |
| Engine testing, detailing issues and resolutions for rockers, plungers, and eccentrics. | 7th Mar 1933 | Box 106 \ 5 scan0082 | |
| List of recommendations for improving a mechanical system, focusing on plunger valves, eccentrics, and rocker shafts. | 7th Mar 1933 | Box 106 \ 5 scan0083 | |
| Power curve data table for the J.II Unit (L.B.) engine with specific settings. | 7th Mar 1933 | Box 106 \ 5 scan0084 | |
| Performance graph plotting Brake Horsepower (BHP) and Brake Mean Effective Pressure (BMEP) against RPM for a Large Bore J III Unit 2.400 engine. | 20th Mar 1933 | Box 106 \ 5 scan0085 | |
| Addition to a report on silent tappets, detailing two experienced troubles and suggesting alterations. | 20th Mar 1933 | Box 106 \ 5 scan0086 | |
| Modifications and improvements to automatic valve tappets. | 27th May 1933 | Box 106 \ 5 scan0087 | |
| Standardisation of valve spring E.58525 and cotter E.58524 for the 25 HP chassis. | 2nd Sep 1932 | Box 106 \ 5 scan0088 | |
| Costs and chassis information for the introduction of a new part. | 30th May 1933 | Box 106 \ 5 scan0089 | |
| The failure of silent tappets due to an oil supply issue. | 30th May 1933 | Box 106 \ 5 scan0090 | |
| Photograph of a machined metal component. | 19th Jun 1933 | Box 106 \ 5 scan0091 | |
| The disappointing test results of a silent tappet mechanism on a J.II. engine. | 19th Jun 1933 | Box 106 \ 5 scan0092 | |
| Improved pieces and a modification for J.3. Silent Tappets due to previous failures. | 28th Jul 1933 | Box 106 \ 5 scan0093 | |
| Exhaust valve failure on a J.111 unit and a proposed modification. | 2nd Aug 1933 | Box 106 \ 5 scan0094 | |
| Testing of a self-adjusting tappet on the 20/25 model. | 2nd Sep 1933 | Box 106 \ 5 scan0095 | |
| Urgent internal order request for one set of plunger springs for automatically adjusting tappets. | 6th Sep 1933 | Box 106 \ 5 scan0096 | |
| Use of white metal for the bearing surface of hydraulically operated tappets. | 6th Sep 1933 | Box 106 \ 5 scan0097 | |
| Specification for an experimental plunger spring. | 9th Sep 1933 | Box 106 \ 5 scan0098 | |
| Modifications to the oil supply for J.III silent tappet plungers. | 9th Sep 1933 | Box 106 \ 5 scan0099 | |
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