| Description | Date | Identifier | |
| Graph showing the power increase due to lower depression in the induction pipe for a 20hp engine. | 30th Mar 1927 | Box 19 \ 7 Scan105 | |
| Blank page with a purple date stamp from Derby. | 1st Apr 1927 | Box 19 \ 7 Scan106 | |
| Graph showing the power increase in a 20 HP engine due to using larger valves. | 31th Mar 1927 | Box 19 \ 7 Scan107 | |
| Performance graph comparing standard vs. larger valves on a 20 HP engine. | 31th Mar 1927 | Box 19 \ 7 Scan108 | |
| Graph comparing Brake Horse Power and Brake Mean Effective Pressure of a standard 20HP engine against a modified version. | 1st Apr 1927 | Box 19 \ 7 Scan109 | |
| Stamped cover page from the Derby works. | 1st Apr 1927 | Box 19 \ 7 Scan110 | |
| Graph comparing gas velocity past standard and larger valves against engine RPM for a 20 HP engine. | 31th Mar 1927 | Box 19 \ 7 Scan111 | |
| Blueprint showing the arrangement of two Zenith carburettors on the 20 HP engine. | 1st Apr 1927 | Box 19 \ 7 Scan112 | |
| Page with a purple ink stamp in the bottom right corner, the main text is illegible. | 1st Apr 1927 | Box 19 \ 7 Scan113 | |
| Delivery of the 14-EX car and altering the engine compression ratio. | 10th May 1928 | Box 19 \ 7 Scan114 | |
| Revisions to the EAC.7 engine with dry and wet liners and requesting compression ratio information. | 24th May 1927 | Box 19 \ 7 Scan115 | |
| Recommending an increased compression ratio for general purpose cars using an aluminium engine. | 27th May 1927 | Box 19 \ 7 Scan116 | |
| Power and compression ratios for the F.2.B. series engine. | 7th Jun 1928 | Box 19 \ 7 Scan117 | |
| Confirming the policy that compression ratios on F.2.B. Series chassis will not be raised for customer delivery without testing by Sales officials and personal sanction. | 1st Jun 1928 | Box 19 \ 7 Scan118 | |
| Compression pressure test results for engine No. SS-3 at various RPMs. | 28th Sep 1928 | Box 19 \ 7 Scan119 | |
| Engine noise investigation, covering piston knock, rocker mechanism, timing gears, and valve mechanism issues. | 25th Sep 1928 | Box 19 \ 7 Scan120 | |
| Graph of compression pressures for a Super Sports Engine at various RPMs. | 25th Sep 1928 | Box 19 \ 7 Scan121 | |
| Blank document with a Print Room date stamp. | 28th Sep 1928 | Box 19 \ 7 Scan122 | |
| Graph showing Mechanical Efficiency and Friction Horse Power against R.P.M. for the Super Sports Engine No SS-3. | 25th Sep 1928 | Box 19 \ 7 Scan123 | |
| On engine compression experiments, torque reactions, and carburettor improvements for the EAC.10 chassis. | 17th Oct 1928 | Box 19 \ 7 Scan124 | |
| Issue of 'booming bodies' in limousines, potential solutions, and the impact of the turbulent head. | 12th Nov 1928 | Box 19 \ 7 Scan125 | |
| Modifications and performance of the 20 HP car 14-G4. | 23th Mar 1929 | Box 19 \ 7 Scan126 | |
| Modifying the India 1V engine cylinder head to address pre-ignition problems by altering the compression ratio. | 28th Mar 1929 | Box 19 \ 7 Scan127 | |
| Preignition issues, comparing the water cooling properties of cast iron and aluminium cylinder heads. | 28th Mar 1929 | Box 19 \ 7 Scan128 | |
| Engine preignition issues at a specific compression ratio and proposed testing methods. | 28th Mar 1929 | Box 19 \ 7 Scan129 | |
| Comparison of performance data for two cars during various hill climbs. | 10th Apr 1929 | Box 19 \ 7 Scan130 | |
| Ignition plug temperature, pre-ignition, and cooling issues on a 20 HP engine. | 10th Apr 1929 | Box 19 \ 7 Scan131 | |
| Proposed engine modifications regarding compression ratios, spark plug cooling, and ignition timing. | 10th Apr 1929 | Box 19 \ 7 Scan132 | |
| Conclusions from a cylinder head test regarding hot spots, compression ratios, and ignition plugs. | 18th Apr 1929 | Box 19 \ 7 Scan133 | |
| Tests regarding pre-ignition trouble on an India-4 turbulent head by comparing cylinder head temperatures. | 18th Apr 1929 | Box 19 \ 7 Scan134 | |
| The effects of pre-ignition on Dadia IV and cast iron engines, comparing turbulent and cast iron cylinder heads. | 18th Apr 1929 | Box 19 \ 7 Scan135 | |
| Spark plug suitability for high compression engines and issues with pre-ignition. | 18th Apr 1929 | Box 19 \ 7 Scan136 | |
| Summary of engine tests comparing aluminium and cast iron cylinder heads, focusing on temperature, pre-ignition, and compression ratios. | 21th Apr 1929 | Box 19 \ 7 Scan137 | |
| Diagram showing the position of thermocouples in an India IV cylinder head. | 21th Apr 1929 | Box 19 \ 7 Scan138 | |
| Heavily faded and almost entirely illegible document page with a purple date stamp. | 18th Apr 1929 | Box 19 \ 7 Scan139 | |
| Surprisingly low performance improvements of a 20 HP engine fitted with a new Turbulent Head. | 22th Apr 1929 | Box 19 \ 7 Scan140 | |
| Performance analysis of a 20 HP engine with a new turbulent head, comparing compression ratios and power increases. | 26th Apr 1929 | Box 19 \ 7 Scan141 | |
| Implementation of two compression ratios and improvements to the SS chassis. | 29th May 1929 | Box 19 \ 7 Scan142 | |
| Engine specifications including timing, power curve data, compression ratio, and clearance volume. | 11th Jul 1929 | Box 19 \ 7 Scan143 | |
| Measuring the S.S. combustion space clearance volume and calculating the compression ratio. | 15th Jul 1929 | Box 19 \ 7 Scan144 | |
| Testing a reduced compression ratio in an S.S. car engine for smoother operation. | 17th Jul 1929 | Box 19 \ 7 Scan145 | |
| Compression ratio tests and findings on test bed engines. | 9th Sep 1932 | Box 19 \ 7 Scan146 | |
| Comparative table of compression ratios and maximum brake horsepower for various car models from 1927 to 1929. | 9th Sep 1932 | Box 19 \ 7 Scan147 | |
| Comparative table of engine specifications (B.HP and Compression Ratio) for various car models from 1927 to 1929. | 9th Sep 1932 | Box 19 \ 7 Scan148 | |
| Comparative table of B.HP and Compression Ratios for various car makes from 1927 to 1929. | 29th Oct 1932 | Box 19 \ 7 Scan149 | |
| Cover note for sketch Hs.747 detailing a modification to the cylinder head compression ratio for the Peregrine engine. | 29th Oct 1932 | Box 19 \ 7 Scan150 | |
| Modification drawing for a cylinder head to reduce the compression ratio. | 28th Oct 1952 | Box 19 \ 7 Scan151 | |
| Heavily faded and damaged document with a purple ink stamp from the Print Room. | 29th Oct 1932 | Box 19 \ 7 Scan152 | |
| On clutch oiling, detailing an issue of oil loss and the results of a fix. | 2nd Jun 1906 | Box 20 \ 1 Scan001 | |
| Note on testing the oiling of a clutch spigot on engine 60525 and a related note on engine 60544. | 2nd Jun 1906 | Box 20 \ 1 Scan002 | |
| Abandoning an experiment to oil a clutch leather in favour of a cotton belting clutch. | 26th Mar 1912 | Box 20 \ 1 Scan003 | |
| Record card detailing tests on oil being fed to a clutch leather when disengaged. | 26th Mar 1912 | Box 20 \ 1 Scan004 | |
| Design request for a lubricator for the clutch trunnion or its lever to lubricate a ball race. | 18th Apr 1912 | Box 20 \ 1 Scan005 | |
| Report log regarding the lubrication of clutch trunnion ball races. | 20th Apr 1912 | Box 20 \ 1 Scan006 | |
| Information on clutch oiling procedures to instruct owners. | 20th Apr 1912 | Box 20 \ 1 Scan007 | |
| Oiling procedures for clutches and whether they should be 'blocked out of a night'. | 20th Apr 1912 | Box 20 \ 1 Scan008 | |
| The testing of multiple trials cars to obtain an average result. | 10th Feb 1914 | Box 20 \ 1 Scan009 | |
| Instructions for the lubrication and treatment of a fabric-lined cone clutch. | 10th Feb 1914 | Box 20 \ 1 Scan010 | |
| Instructions for lubricating a dry or squeaking clutch. | 10th Feb 1914 | Box 20 \ 1 Scan011 | |
| Responding to a request for a simplified guide on clutch lubrication, attaching a relevant report. | 10th Feb 1914 | Box 20 \ 1 Scan012 | |
| Proposed note for the Instruction Book on how to remedy squeaky clutches. | 18th Feb 1914 | Box 20 \ 1 Scan013 | |
| Instructions for clutch lubrication and suitability for inclusion in the instruction book. | 19th Feb 1914 | Box 20 \ 1 Scan014 | |
| Request for a note to be inserted into the instruction book on how to remedy squeaky clutches. | 24th Feb 1914 | Box 20 \ 1 Scan015 | |
| Follow-up request for an opinion on a suggested paragraph for an instruction book regarding clutch lubrication. | 25th Feb 1914 | Box 20 \ 1 Scan016 | |
| Wording and suitability of an article on clutch lubrication for an instruction book. | 25th Feb 1914 | Box 20 \ 1 Scan017 | |
| Improvements for cone clutches, focusing on oil retention, suitable oil types, and the practice of propping clutches out. | 13th Jul 1914 | Box 20 \ 1 Scan018 | |
| Potential changes to the clutch instruction book regarding cleaning with paraffin and oil levels. | 20th Jul 1914 | Box 20 \ 1 Scan019 | |
| Appropriate oil viscosity for the clutch and its impact on the instruction book. | 20th Jul 1914 | Box 20 \ 1 Scan020 | |
| Criticism on Mr. Royce's memo R11/P20714 regarding an instruction book. | 21th Jul 1914 | Box 20 \ 1 Scan021 | |
| Technical letter regarding clutch operation, specifically the effects of using oil and paraffin. | 22th Jul 1914 | Box 20 \ 1 Scan022 | |
| Lubrication of a clutch, forwarding a report to Mr Royce. | 23th Jul 1914 | Box 20 \ 1 Scan023 | |
| Proposing changes to the clutch lubrication section of the Instruction Book. | 27th Jul 1914 | Box 20 \ 1 Scan024 | |
| Use of a graphite-lubricated plate clutch for Mr. Williamson's chassis, including an extract from his letter. | 13th Nov 1914 | Box 20 \ 1 Scan025 | |
| Experiments with Mr. Williamson's Chassis, noting that oil was not a success. | 23th Oct 1914 | Box 20 \ 1 Scan026 | |
| Notice concerning clutch over-oiling issues due to incorrect fitting on cars at the Derby factory. | 8th Jun 1921 | Box 20 \ 1 Scan027 | |
| Letter discussing tests and concerns regarding the lubrication of a clutch spigot. | 7th Feb 1923 | Box 20 \ 1 Scan028 | |
| Test report detailing various methods for oiling a clutch spigot. | 14th Feb 1923 | Box 20 \ 1 Scan029 | |
| Test report page detailing modifications and results for clutch spigot lubrication issues, numbered tests 8 through 14. | 14th Feb 1923 | Box 20 \ 1 Scan030 | |
| Test results for oil lubrication of a clutch spigot and flywheel assembly. | 27th Feb 1923 | Box 20 \ 1 Scan031 | |
| Letter from the Springfield, MA office to Derby, England regarding the lubrication of the clutch spigot. | 27th Feb 1923 | Box 20 \ 1 Scan032 | |
| Letter discussing the history, issues, and design changes related to the lubrication of the clutch spigot. | 27th Feb 1928 | Box 20 \ 1 Scan033 | |
| Technical note discussing clutch and spigot lubrication, and remedies for overoiling issues. | 20th Mar 1923 | Box 20 \ 1 Scan034 | |
| New scheme for lubricating the clutch spigot using a syringe instead of the automatic system. | 20th Mar 1923 | Box 20 \ 1 Scan035 | |
| Recommendation to adopt a scheme for an oil pipe to lubricate the clutch spigot. | 9th Apr 1923 | Box 20 \ 1 Scan036 | |
| Replacing the automatic lubrication system for the clutch spigot with hand oiling. | 9th Apr 1923 | Box 20 \ 1 Scan037 | |
| Issues with the 40/50 HP clutch spigot lubrication and a new scheme being tested. | 10th May 1923 | Box 20 \ 1 Scan038 | |
| Disagreeing with altering the 40/50 clutch spigot lubrication from the standard valve and wick pattern. | 17th May 1923 | Box 20 \ 1 Scan039 | |
| Commenting on American Proposal Sheet No.41 regarding the lubrication of a clutch spigot bearing. | 19th Nov 1924 | Box 20 \ 1 Scan040 | |
| Technical memo discussing modifications to the clutch lubrication procedure detailed in Depot Sheet No. Hm. 25 for Phantom and 20 HP chassis. | 24th Feb 1927 | Box 20 \ 1 Scan041 | |
| Instructions for lubricating the clutch on a Phantom model. | 29th Aug 1928 | Box 20 \ 1 Scan042 | |
| Instructions for the lubrication of the single plate clutch for the Phantom model. | 28th Feb 1927 | Box 20 \ 1 Scan043 | |
| Excessive oil supply to the clutch trunnion and servo cams, requesting an alteration to the lubrication system. | 14th Aug 1929 | Box 20 \ 1 Scan044 | |
| Issues and testing related to the lubrication of the Phantom II clutch. | 30th Oct 1929 | Box 20 \ 1 Scan045 | |
| New scheme for the automatic lubrication of the Phantom II clutch spigot bearing from the gearbox. | 6th Nov 1929 | Box 20 \ 1 Scan046 | |
| Modifications for the automatic lubrication of the 'Japan' clutch spigot bearing on a 20/25 HP model. | 1st Nov 1923 | Box 20 \ 1 Scan047 | |
| Lubrication issues with the S.S. Clutch and the resulting modifications. | 3rd Nov 1929 | Box 20 \ 1 Scan048 | |
| Clutch oiling tests, focusing on the collector ring, Ferodo surfaces, and modifications to floating ball bearings. | 1st Nov 1929 | Box 20 \ 1 Scan049 | |
| Modifications to a lubrication scheme and clutch assembly. | 1st Nov 1929 | Box 20 \ 1 Scan050 | |
| Blueprint of the oiling scheme for an S.S. clutch. | 8th Nov 1929 | Box 20 \ 1 Scan051 | |
| Mostly blank, folded page with a 'Print Room' date stamp in the bottom right corner. | 13th Nov 1928 | Box 20 \ 1 Scan052 | |
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