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Introduction
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Market Position
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Market Position:
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The MG MGB was a highly successful British sports car produced by BMC and later British Leyland. It was positioned as an affordable, practical, and stylish sports car for the masses, competing with cars like the Triumph TR series, Datsun Z-cars (later in its production), and Alfa Romeo Spiders. Its long production run and widespread appeal solidified its place as an iconic classic sports car.
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Competitive Analysis
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Competitive Analysis:
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The MGB offered a blend of performance, handling, and affordability that set it apart. While rivals like Triumph focused on raw power, the MGB emphasized a more comfortable and reliable driving experience, particularly with its unibody construction which provided a more refined ride than body-on-chassis designs. Its open-top nature and iconic British styling were significant draws.
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Key Features
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Key Features:
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Monocoque (unibody) construction, robust BMC 'B-series' engine, independent front suspension, rack-and-pinion steering, front disc brakes, iconic British sports car styling, convertible and GT coupe variants, widespread availability of parts and support.
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Manual Coverage
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Systems Covered
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Systems Covered:
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Engine (all variants), Fuel System, Ignition System, Cooling System, Lubrication System, Exhaust System, Clutch, Gearbox (4-speed manual, optional overdrive, 3-speed automatic), Driveshaft, Differential, Suspension (front and rear), Steering, Brakes (front discs, rear drums), Electrical System (lighting, charging, starting, instrumentation, wiring diagrams), Bodywork (construction, panels, doors, windows, convertible top), Interior Trim, Heating System.
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Procedures Included
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Procedures Included:
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Routine maintenance (tune-ups, fluid changes, filter replacements), engine overhaul and rebuilding, transmission repair and overhaul, suspension component replacement and alignment, brake system overhaul and bleeding, electrical system diagnosis and repair, body panel repair and replacement, convertible top maintenance, troubleshooting guides for common faults, torque specifications, special tool requirements.
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Technical Depth
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Technical Depth:
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Comprehensive, ranging from basic adjustments and maintenance to complete engine and transmission rebuilds, full electrical system diagnostics, and detailed bodywork procedures. Suitable for professional mechanics and skilled DIY enthusiasts.
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Bodywork Repair
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Bodywork Repair:
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Detailed procedures for panel replacement, rust repair, welding techniques, door and hood alignment, convertible top frame and fabric maintenance, and window sealing.
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Electrical Diagrams
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Electrical Diagrams:
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Complete, easy-to-read wiring diagrams for all circuits, essential for troubleshooting electrical issues.
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Engine Specifications
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Primary Engine
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Primary Engine:
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BMC 'B-Series' Inline-4 OHV
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Engine Variants
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Engine Variants:
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1.8L (1798cc) OHV Inline-4. Early models (1962-1964) featured the MGB 'B-series' 3-bearing crank engine. Later models from 1965 onwards used the 4-bearing crank engine for improved durability. North American market cars received engines with lower compression ratios and emission controls later in the production run (e.g., US spec 1975+ with emissions equipment).
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Performance Early
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Performance Early:
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Approx. 95-100 bhp @ 5400 rpm, 110-115 lb-ft torque @ 3000 rpm.
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Performance Late Us Spec
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Performance Late Us Spec:
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Approx. 70-78 bhp @ 4500 rpm, 95-100 lb-ft torque @ 2500 rpm (due to emissions controls and lower compression).
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Fuel System
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Fuel System:
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Twin SU Carburetors (HS4 or HIF4 depending on year and market). Later US models may have used ZS carburetors or injection systems (though less common).
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Ignition System
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Ignition System:
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Distributor-based, coil ignition. Points and condenser type, later models may feature electronic ignition conversions.
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Cooling System
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Cooling System:
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Pressurized, radiator cooling with fan (engine-driven). Thermostatically controlled.
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Block Material
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Block Material:
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Cast Iron
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Head Material
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Head Material:
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Cast Iron
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Bore
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Bore:
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3.46 inches (88.9 mm)
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Stroke
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Stroke:
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3.50 inches (88.9 mm)
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Compression Ratio Early
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Compression Ratio Early:
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8.0:1 or 8.4:1
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Compression Ratio Late Us Spec
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Compression Ratio Late Us Spec:
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7.0:1 or 7.5:1
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Maintenance
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Service Intervals Oil Change
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Service Intervals Oil Change:
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Every 3,000 miles or 6 months, whichever comes first. Use appropriate oil viscosity for climate.
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Service Intervals Grease Points
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Service Intervals Grease Points:
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Regular lubrication of kingpins, shackle pins, and other greasing points every 1,000-2,000 miles.
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Service Intervals Tune Up
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Service Intervals Tune Up:
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Recommended every 6,000-12,000 miles, including ignition timing, carburetor adjustment, valve clearance check, spark plug replacement.
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Fluid Specifications Engine Oil
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Fluid Specifications Engine Oil:
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API SF/CD or equivalent. Viscosity: 20W-50 is commonly recommended for general use, 10W-30 or 10W-40 in colder climates, 15W-40 or 20W-50 in hotter climates or for high-mileage engines. Check manual for specific recommendations.
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Fluid Specifications Coolant
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Fluid Specifications Coolant:
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50/50 mix of ethylene glycol antifreeze and distilled water.
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Fluid Specifications Brake Fluid
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Fluid Specifications Brake Fluid:
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DOT 3 or DOT 4 brake fluid (glycol-based). Ensure compatibility with seals.
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Fluid Specifications Gearbox Oil
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Fluid Specifications Gearbox Oil:
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GL-4 Hypoid Gear Oil (SAE 90 or 80W-90).
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Fluid Specifications Differential Oil
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Fluid Specifications Differential Oil:
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GL-4 Hypoid Gear Oil (SAE 90 or 80W-90). Limited-slip differential fluid not applicable unless modified.
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Fluid Capacities Engine Oil
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Fluid Capacities Engine Oil:
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5.5 US quarts (5.2 Liters) with filter change.
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Fluid Capacities Cooling System
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Fluid Capacities Cooling System:
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Approx. 11 US pints (5.2 Liters).
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Fluid Capacities Gearbox
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Fluid Capacities Gearbox:
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Approx. 3.5 US pints (1.6 Liters).
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Fluid Capacities Differential
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Fluid Capacities Differential:
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Approx. 2.5 US pints (1.2 Liters).
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Known Issues
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Known Issues:
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Rust (particularly sills, wheel arches, and floor pans), oil leaks (especially from crankshaft rear main seal and oil filter housing), overheating (due to radiator capacity and cooling fan efficiency), electrical gremlins (faulty wiring, switches, earth points), clutch slave cylinder issues, carburetor tuning problems (especially with SU's), weak suspension bushings, steering rack wear.
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Filter Part Numbers Oil
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Filter Part Numbers Oil:
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Examples: Fram PH8A, Purolator L30001, Wix 51515 (cross-reference with specific MGB applications).
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Filter Part Numbers Fuel
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Filter Part Numbers Fuel:
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In-line fuel filter, various aftermarket part numbers apply.
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Tune Up Parts Spark Plugs
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Tune Up Parts Spark Plugs:
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Champion RN3C or equivalent (e.g., NGK BP6ES).
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Tune Up Parts Points
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Tune Up Parts Points:
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Standard distributor points and condenser set.
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