How to Build & Power Tune Weber & Dellorto Dcoe, Dco/Sp & Dhla Carburettors 3rd Edition

Des Hammill is a professional engineer with huge experience of building successful and reliable racing engines and solving the problems associated with all aspects of high performance applications. Des has written many of Veloce's SpeedPro series books.

• (c) Des Hammill & Veloce Publishing CHAPTER 1: KNOW YOUR CARBURETOR - STRIPDOWN & INSPECTION 14 Know your carburetor - major components 14 Chokes and auxiliary venturis 14 Idle mixture adjusting screws 15 Main jet, emulsion tube & air corrector 15 Progression hole inspection covers 16 Idle jet 17 Accelerator pump jets 18 Accelerator pump 19 Floats 20 Needle & seat 22 Stripdown - general advice 22 Cleaning components 22 Fuel enrichment devices - special note 24 Stripdown procedure 25 Fuel enrichment device - blocking off discharge holes (Weber only) 26 Inspecting components for wear and damage 27 Weber & Dellorto 27 Weber only 27 Dellorto only 27 Difficult procedures 27 Clearing passageways 27 Throttle butterfly, spindle & bearings - maintenance, removal & refitting 28 Removing damaged threaded components 34 Removing jammed chokes and auxiliary venturis 35 CHAPTER 2: REBUILDING 37 Needle valve & seat (Dellorto) 37 Floats & fulcrum pin (Dellorto) 37 Fulcrum pin - checking 37 Floats - checking 37 Floats & pin - fitting 38 Float level - setting (Dellorto) 38 Top cover (Dellorto) 39 Body components (Dellorto) 39 Needle valve & seat (Weber) 44 Floats & fulcrum pin (Weber) 44 Fulcrum pin - checking 44 -------------------------------------------------------------------------------- Floats - checking 44 Floats and fulcrum pin - fitting 45 Float level - setting (Weber) 45 Top cover (Weber) 45 Body components (Weber) 49 CHAPTER 3: FUEL MANAGEMENT, AIR FILTERS & RAM TUBES 54 Fuel filters 54 Fuel lines (pipes) & fittings 54 Air filters 55 Ram tubes (stacks) 56 Fuel pressure 56 CHAPTER 4: CHOOSING THE COMPONENTS FOR YOUR CARBURETOR/S 58 Components - initial selection 58 Choke size versus carburetor size 58 Choke size - selecting 59 Idle jet - selecting 61 Idle jet codes (Weber) 61 Idle jet codes (Dellorto) 62 Idle jet & air bleed component - selection 62 Idle mixture and progression holes 63 Idle screw adjustment procedure 64 Main jet - selection 64 Emulsion tube - selection 64 Air corrector - selection 65 Auxiliary venturi - selection 66 Accelerator pump jet - selection 68 Accelerator pump intake/ discharge valve 69 Needle valve - selection 69 CHAPTER 5: MANIFOLD PREPARATION & CARBURETOR FITTING 70 Intake manifold - checking & preparation 70 The importance of stud alignment 70 Carburetor - checking fit 71 Anti-vibration mountings 73 -------------------------------------------------------------------------------- Carburetor/s - fitting to manifold 74 CHAPTER 6: TESTING & SET-UP 75 Idle speed 75 Fuel level & needle valve operation - checking 75 Throttle - initial adjustment and synchronization 76 Throttle arm fit 76 Throttle - initial setting (single carburetor) 76 Throttle - initial set-up & synchronization (multiple carburetors) 76 Idle mixture - initial adjustment 76 Throttle (linked throttle arm type) - final synchronization 79 Throttle (bar & pushrod type) - final synchronization 81 Full throttle check 82 Idle jet alteration (fuel component) 82 Ignition timing - general 83 Idle jets/air bleeds - final selection 84 Weber 85 Dellorto 86 Idle mixture screws - final setting 87 Accelerator pump jets - final selection 88 CHAPTER 7: TESTING & PROBLEM SOLVING 90 Rolling road (dyno) testing procedure 90 Track testing procedure 91 Solving problems - low to mid-range rpm 91 Solving problems - high rpm 92 Webers - fuel leakage from fuel enrichment device 92 Webers - adapting for off-road applications 93 Return springs 94 Tuning by exhaust gas co% 94 Maintenance 95 -------------------------------------------------------------------------------- CHAPTER 8: JETTING/SETTING EXAMPLES 96 BMC/Rover A-Series 1275cc engine (Weber) 96 Ford 'Pinto' 2000cc SOHC standard engine (Weber) 97 Ford 'Pinto' 2000cc SOHC standard engine (Dellorto) 97 Vauxhall 2000cc 16v engine (Dellorto) 97 Ford RS 2000cc SOHC Escort 98 Ford Sierra Cosworth 2000cc (naturally aspirated)(Weber) 98 BMC B-Series 1900cc MGB engine (Weber) 98 Toyota 4A-GE 1600cc 16-valve MR2 engine (Weber) 98 MG 1940cc alloy 8 port Magnette engine 98 Ford 1600cc Crossflow engine (Weber) 99 Jaguar XK 3.8 litre engine (Dellorto) 99 Ford 1628cc Crossflow engine (Weber) 99 Ford 'Pinto' 2100cc engine fitted to Formula 27 sports car (Dellorto) 99 2000cc Ford Sierra Cosworth racing engine (Dellorto) 99 Ford 1760cc Crossflow engine (Dellorto) 100 BMC/Rover 1275cc A-series engine (Dellorto) 100 DETAILS OF COMPLEMENTARY SPEEDPRO BOOKS 101-108 GLOSSARY OF TERMS 109 INDEX 111-112 (c) Des Hammill & Veloce Publishing