| Description | Date | Identifier | |
| Outlining three schemes for the revision of the 25HP 'Japan' engine. | 3rd Nov 1930 | Box 103 \ 4 scan0065 | |
| Request to remove a cylinder head and block from 12-G4 and fit an aluminium cover plate. | 6th Nov 1930 | Box 103 \ 4 scan0066 | |
| Secret memo regarding the machining feasibility of a new 28HP cylinder block. | 10th Jan 1931 | Box 103 \ 4 scan0067 | |
| Print for a Japan 3 cylinder head, replacing an earlier version. | 19th Jan 1931 | Box 103 \ 4 scan0068 | |
| Modifications to the Japan 3 cylinder head compression ratio and starting torque. | 1st Jan 1931 | Box 103 \ 4 scan0069 | |
| Secret memo discussing the distribution of drawings for the Japan 3 valve rocker gear and cylinder head. | 9th Feb 1931 | Box 103 \ 4 scan0070 | |
| Design changes for the 'Japan 3' engine's valve rocker gear and cylinder head. | 1st Feb 1931 | Box 103 \ 4 scan0071 | |
| Proposed changes to a casting, specifically for plugging methods and inspection holes on the ends of the head. | 20th Apr 1931 | Box 103 \ 4 scan0072 | |
| The performance of a 25 HP integral cast iron crankcase and cylinder block, detailing flywheel performance, gear rattles, and weight issues. | 20th Apr 1931 | Box 103 \ 4 scan0073 | |
| Report page discussing experimental results on construction methods, referencing American practices for efficiency and cost reduction. | 20th Apr 1931 | Box 103 \ 4 scan0074 | |
| Recommending the adoption of an integral crankcase and cylinder block for the 20/25 HP model based on a successful 300-mile test drive. | 21th Apr 1931 | Box 103 \ 4 scan0075 | |
| Requesting a blueprint for a 20/25 Cylinder Head, Japan 1. | 11th May 1931 | Box 103 \ 4 scan0076 | |
| Part number changes for an increased valve lift on a 20/25 HP chassis cylinder head. | 14th May 1931 | Box 103 \ 4 scan0077 | |
| Requesting a 'Japan head' fitted with longer valves and higher lift rockers for a test run on a test bed unit. | 12th Jun 1931 | Box 103 \ 4 scan0078 | |
| Request for alterations to a C.I. head, involving machining valve clearances and fitting standard inlet valves in two stages for testing. | 15th Jun 1931 | Box 103 \ 4 scan0079 | |
| Replacement parts for an increased valve lift experiment on a 20/25 HP chassis. | 1st Jul 1931 | Box 103 \ 4 scan0080 | |
| Design modifications for the Japan cylinder head and valve rockers. | 24th Jul 1931 | Box 103 \ 4 scan0081 | |
| The dispatch of a drawing print for a J.3. crankcase, cylinder block, and crankshaft, with an update on future work. | 29th Mar 1931 | Box 103 \ 4 scan0082 | |
| Instructions for achieving a 5.7 to 1 compression ratio for the 20/25 China model by machining a piston. | 2nd Sep 1931 | Box 103 \ 4 scan0083 | |
| General scheme for the crankcase, cylinder block, and crankshaft, noting changes to the rear main bearings. | 9th Sep 1931 | Box 103 \ 4 scan0084 | |
| Discrepancies in horsepower from different 'Japan' cylinder heads due to modifications. | 16th Sep 1931 | Box 103 \ 4 scan0085 | |
| Cross-sectional and inverted plan diagrams of a Cylinder Head (India IV) at a 5.1 to 1 ratio. | 15th Sep 1931 | Box 103 \ 4 scan0086 | |
| Obtaining and testing different types of cylinder liners for the Japan III project. | 23th Sep 1931 | Box 103 \ 4 scan0087 | |
| The machining and heat treatment process for cylinders supplied in a rough condition. | 23th Sep 1931 | Box 103 \ 4 scan0088 | |
| Instructions for preparing extra 'Nimol' iron cylinder liner castings for nitriding experiments. | 24th Sep 1931 | Box 103 \ 4 scan0089 | |
| Suggestion to use Austenitic nitro-hardened steel for car cylinder liners, considering the cost and reliability benefits. | 28th Sep 1931 | Box 103 \ 4 scan0090 | |
| Problems and potential solutions for an aluminium cylinder block with wet steel liners, titled 'JAPAN III'. | 6th Oct 1931 | Box 103 \ 4 scan0091 | |
| The decision to test the 18-GIV cylinder head without inserted valve seats. | 3rd Oct 1931 | Box 103 \ 4 scan0092 | |
| Instructions for an experiment fitting two single carburetters to a 20/25 HP chassis with a turbulent cylinder head. | 29th Oct 1931 | Box 103 \ 4 scan0093 | |
| The examination of a J. S. Cylinder Head casting, its satisfactory progress, and anxieties over valve passage obstructions. | 30th Nov 1931 | Box 103 \ 4 scan0094 | |
| Improvements to the gas bends on a J.3 cylinder head, referencing print LeC.2980. | 31th Dec 1931 | Box 103 \ 4 scan0095 | |
| Improvements to the exhaust and inlet gas bends for the J.3. cylinder head. | 7th Dec 1931 | Box 103 \ 4 scan0096 | |
| Listing parts required for Japan III engine components, referencing specific blueprints and schemes. | 11th Dec 1931 | Box 103 \ 4 scan0097 | |
| Continuation of a parts list for sections 5080 and 5231, referencing carburettor and induction system components. | 11th Dec 1931 | Box 103 \ 4 scan0098 | |
| Requesting an update on the availability of cut up sections of a J.3 cylinder head. | 23th Dec 1931 | Box 103 \ 4 scan0099 | |
| Test results for a J. 3. Cylinder Head modification to resolve an overheating issue. | 20th Apr 1932 | Box 103 \ 4 scan0100 | |
| Sketch of a cylinder head showing the water holes that are to be blanked. | 14th Apr 1932 | Box 103 \ 4 scan0101 | |
| Requesting a trial and report on new nickel alloy cylinder head gaskets for a 20/25 HP Chassis. | 28th May 1932 | Box 103 \ 4 scan0102 | |
| Alternative cylinder head design features following a telephone conversation. | 30th May 1932 | Box 103 \ 4 scan0103 | |
| Engine design modifications focusing on induction systems and resolving overheating issues. | 30th May 1932 | Box 103 \ 4 scan0104 | |
| Alternative cylinder head designs, comparing water cooling of the sparking plug boss. | 3rd Jun 1932 | Box 103 \ 4 scan0105 | |
| Sending drawings for Peregrine and Japan I cylinder heads, detailing a modification for a 14 m/m sparking plug to improve water ways. | 3rd Jun 1932 | Box 103 \ 4 scan0106 | |
| The unsatisfactory performance of corrugated Nickel Type Cylinder Head Gaskets for the 20/25HP Chassis due to leaks. | 22th Jun 1932 | Box 103 \ 4 scan0107 | |
| Engine cylinder head compression ratios, detonation, and pre-ignition for the 'Japan 3' project. | 9th Sep 1932 | Box 103 \ 4 scan0108 | |
| Instructions for modifying a J.II cylinder head to fit a J.III engine. | 17th Jan 1933 | Box 103 \ 4 scan0109 | |
| Clarifying confusion over the J.3 cylinder head type and requesting production of a turbulent head. | 19th May 1933 | Box 103 \ 4 scan0110 | |
| Test report on Induction Pipe LeC.3637 and a 1 5/8' S.U. Carburetter for a 25 HP Type Cylinder Head. | 7th Mar 1934 | Box 103 \ 4 scan0111 | |
| Engine performance and distribution with different pipe and carburetter arrangements. | 7th Mar 1934 | Box 103 \ 4 scan0112 | |
| Performance graph for a 1 5/8' SU carburettor on a 20/25 HP engine head, comparing two different induction pipes. | 7th Mar 1934 | Box 103 \ 4 scan0113 | |
| Performance graph for a 1 5/8' SU carburettor on a standard 25HP cylinder head, comparing different induction configurations. | 7th Mar 1934 | Box 103 \ 4 scan0114 | |
| Blueprint for an experimental induction pipe for a 25 HP type cylinder head. | 9th Mar 1934 | Box 103 \ 4 scan0115 | |
| Proposal to conduct experiments on extra cylinder lubrication using a modified 20/25 Unit running on five cylinders. | 26th Apr 1934 | Box 103 \ 4 scan0116 | |
| Required modifications to compare the roughness of 20/25 HP and Bentley cylinder heads. | 28th May 1934 | Box 103 \ 4 scan0117 | |
| Parts list comparing components for different engine head configurations. | 2nd Nov 1934 | Box 103 \ 4 scan0118 | |
| Request to prepare studs for fitting a Bentley cylinder head to car 18-G-IV for testing the Spectre induction system. | 2nd Nov 1934 | Box 103 \ 4 scan0119 | |
| Requesting clarification on dimensions for the 20/25 HP chassis cylinder block cast induction passage. | 3rd Nov 1934 | Box 103 \ 4 scan0120 | |
| Clarifying bore dimensions for the induction passage of a 20/25 HP chassis cylinder block. | 16th Nov 1934 | Box 103 \ 4 scan0121 | |
| Blueprint showing the vertical section and dimensions of an induction passage. | 1st Jan 1935 | Box 103 \ 4 scan0122 | |
| Proposing a new method for fine boring 20-HP cylinders and a plan for testing. | 1st Jan 1935 | Box 103 \ 4 scan0123 | |
| Sending a 20/25 Cylinder Head for modification. | 2nd Jan 1935 | Box 103 \ 4 scan0124 | |
| Standardisation of an oval passage through the cylinder block for the 20/25 model to improve top speed. | 10th Jan 1935 | Box 103 \ 4 scan0125 | |
| Cost estimation for extra jigs and tools for the 'H' series chassis and its production start. | 9th Jan 1935 | Box 103 \ 4 scan0126 | |
| Cylinder distortion tests for the Spectre & J. III engines, detailing the effects of heat on centricast iron liners. | 18th Feb 1935 | Box 103 \ 4 scan0127 | |
| Cylinder bore expansion tests for Spectre and J.III Unit Centricast Iron Liners. | 1st Feb 1935 | Box 103 \ 4 scan0128 | |
| Explanation of the color-coded figures on charts denoting bore dimensions under cold, heated, and bolted conditions. | 18th Feb 1935 | Box 103 \ 4 scan0129 | |
| Measurements of Spectre Centri-cast and Austenitic Steel cylinder liners detached from the cylinder block. | 14th Feb 1935 | Box 103 \ 4 scan0130 | |
| Measurement log for J.3 cylinders with heads in position, made from Nimol Iron. | 12th Feb 1935 | Box 103 \ 4 scan0131 | |
| Dimensional measurements of Spectre No. 2 engine cylinder bores for A and B blocks. | 11th Feb 1935 | Box 103 \ 4 scan0132 | |
| Dimensional analysis of Spectre engine cylinder bores with heads in position. | 12th Feb 1935 | Box 103 \ 4 scan0133 | |
| Previously designed 20/25 HP cylinder head and its potential application to a new large bore engine. | 10th Aug 1935 | Box 103 \ 4 scan0134 | |
| Requesting an order for six more C. & A. Cylinder Head Gaskets for a 3.520 inch bore engine. | 13th Aug 1935 | Box 103 \ 4 scan0135 | |
| Request to fit an induction pipe (Hs.2075) for trial on car 13-G-IV, which requires an increase in stud centres. | 7th Oct 1935 | Box 103 \ 4 scan0136 | |
| Requesting the fitting of a new 20/25 cylinder head to experimental car Ex.19456. | 21th Oct 1935 | Box 103 \ 4 scan0137 | |
| Engine specifications for the J-III model with dry liner construction, comparing it to a Bentley engine. | 29th Oct 1935 | Box 103 \ 4 scan0138 | |
| Requesting a fortnightly progress report on the production of the new turbulent cylinder head for the 20/25 model. | 5th Nov 1935 | Box 103 \ 4 scan0139 | |
| Urgent request to modify an induction pipe and exhaust manifold to fit a new turbulent head on a 25/30 HP engine. | 3rd Jan 1926 | Box 103 \ 4 scan0140 | |
| The development and performance of a new turbulent cylinder head and induction pipe drain for the large bore 20/25 model. | 22th Jan 1936 | Box 103 \ 4 scan0141 | |
| Reviewing the clutch and flywheel development for the 20/25 model, including comparisons with Bentley parts. | 22th Jan 1936 | Box 103 \ 4 scan0142 | |
| Test report on the induction system drainage scheme for the 25/30 HP Engine. | 22th Jan 1936 | Box 103 \ 4 scan0143 | |
| Induction pipe drainage tests, including results and conclusions. | 22th Jan 1936 | Box 103 \ 4 scan0144 | |
| Graph showing air/fuel ratio distribution versus engine RPM for a 25/30 HP engine. | 1st Jul 1931 | Box 103 \ 4 scan0145 | |
| Power comparison graph showing B.HP and B.M.E.P. versus R.P.M. for 20/25 HP and 25/30 HP engine configurations. | 2nd Jan 1936 | Box 103 \ 4 scan0146 | |
| Tests on a non-return drainage valve for the 25/30 HP engine induction system. | 23th Jan 1936 | Box 103 \ 4 scan0147 | |
| Analysis of engine starting depression levels and air intake bend performance with different carburetter configurations. | 23th Jan 1936 | Box 103 \ 4 scan0148 | |
| Report concluding the Rm.30 intake bend was a failure and identifying a better alternative. | 23th Jan 1936 | Box 103 \ 4 scan0149 | |
| Graph showing air/fuel ratio distribution versus RPM for a Stromberg carburettor at full and half throttle. | 22th Jan 1936 | Box 103 \ 4 scan0150 | |
| Graph showing induction system distribution, plotting air/fuel ratio against RPM at full and half throttle. | 22th Jan 1936 | Box 103 \ 4 scan0151 | |
| Graph of induction system distribution, plotting air/fuel ratio against RPM under full and half throttle conditions. | 22th Jan 1936 | Box 103 \ 4 scan0152 | |
| Graph showing induction system distribution by plotting air/fuel ratio against RPM at full and half throttle. | 22th Jan 1936 | Box 103 \ 4 scan0153 | |
| Performance curve for an induction system non-return valve, charting fuel flow against ball travel. | 24th Feb 1936 | Box 103 \ 4 scan0154 | |
| Request to produce a modified turbulent type cylinder head for a Large Bore 25 HP engine. | 24th Feb 1936 | Box 103 \ 4 scan0155 | |
| Results of tests involving the removal of the turbulent lip from a 20/25 4 1/4 bore cylinder head. | 20th Mar 1936 | Box 103 \ 4 scan0156 | |
| Ignition and detonation test results for engine B-9 with a modified cylinder head E.60660. | 20th Mar 1936 | Box 103 \ 4 scan0157 | |
| Ignition and detonation test data for Engine No. B-9. | 20th Mar 1936 | Box 103 \ 4 scan0158 | |
| Power comparison data for an EB.615 head fitted to a standard engine with an open exhaust. | 20th Mar 1936 | Box 103 \ 4 scan0159 | |
| Test data sheet for Bentley Development on a deturbulated Cylinder Head, showing performance metrics. | 20th Mar 1936 | Box 103 \ 4 scan0160 | |
| Test data on detonation and ideal ignition advance for an EB. 615 silenced cylinder head. | 20th Mar 1936 | Box 103 \ 4 scan0161 | |
| Performance data table for Bentley Development Cylinder Head H62118. | 20th Mar 1936 | Box 103 \ 4 scan0162 | |
| Performance graph for a 25/30 HP Turbulence Cylinder Head, showing B.M.E.P. and ignition advance against R.P.M. | 27th Apr 1936 | Box 103 \ 4 scan0163 | |
| Circulation issue with a head under braking conditions and a proposed modification. | 27th Apr 1936 | Box 103 \ 4 scan0164 | |
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