MGB’s Restoration & Modernisation brief

An accesible brief of a MGB restoration process

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MGB Restomod brief

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The V8 engine

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The V8 engine is much lighter than the four-cylinder variant. It weighs 40 lbs less.

The block was made from aluminium; the cylinder heads were die-cast aluminium with iron valve guides and valve seats. The actual design of the engine was fairly standard, with a five-main bearing crankshaft and a centrally mounted camshaft driven by a chain.

The factory V8 cars had an 88.9mm bore with a 71.1mm stroke giving an engine capacity of 3528cc.

Modifications were made to enable the engine to fit into the MGB engine bay to avoid any bonnet bulges or alterations. The inlet manifold was constructed so the carburettors could be installed at the rear of the engine, very close to the heater box; this gave just enough clearance for the bonnet to close.

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Not much changed in the engine compartment throughout the MGB GT V8 production. Many parts were used from the standard MGB, such as
the pedal box and heater system.

The V8 engine had to use a remote oil filter that was situated on the radiator support panel on the left-hand side with the pipes running to the oil cooler mounted on the front panel.

MGB interior trim

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Minimal interior additions were made, with headrests becoming a standard fitment and inertia-reel seat belts on the GT V8 models, these were both extra on the regular MGB.

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MGB GT V8 brakes

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It’s always an excellent decision to improve the brakes on any car that is tuned to go faster than the original design, and the brakes were improved on the GT V8. The front brake system was fitted with larger brake callipers along with uprated brake discs, which helped bring the car to a safe stop.

Front disc assembly

A remote brake servo unit soon became standard on the V8 model to give some assistance. This setup was soon included on all MGBs, whether they were 1800cc or 3500cc versions.

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Fuel system

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The V8 engine used a pair of HIF6 SU carburetors fitted to the rear of the engine compartment, a very similar design to the 1.8 MGB carburetors but with a choke diameter of 1 1/3 in. An air box was designed to fit across both the carburetors; this was very shallow, as it had to fit in front of the heater box, the air filters themselves protruding forward over the rocker covers.

All CCHL models have improved the air filters. The original equipment SU electric fuel pump was a standard item found on all MGB’s, MGB V8 and MGC cars. It was effective enough to cope with all engine sizes; unfortunately they were not 100% reliable.

MGB Restomod brief - MGB Fuel system - CCHL

Servo unit on V8

To help keep the fuel consumption to a reasonable level, the V8 was fitted with the MGC’s 3.07:1 differential.

This aided long-distance cruising, all V8 cars equipped with the overdrive gearbox made covering longer distances more pleasurable. No changes were made to the rear axle, although the prop shaft material was stronger for the V8 cars.

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MGB V8 Exhaust System

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Like many components for the V8 derivative, there was only one choice, and the same exhaust system was fitted to all models.

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Cooling System Like Modern Cars

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Improvements were made to cool the bigger engine; the radiator was moved towards the front of the car. This gave more space in the engine bay, allowing the engine to fit, a pair of twin cooling fans were slotted between the radiator and the front panel.

The fans were thermostatically controlled and set to kick in at 90°C. The design of the front grille also helped by allowing airflow to pass through more easily, again helping to keep the temperature down to a manageable level.

The cooling system was semi-sealed and came with a separate expansion tank fitted on the left inner wing. This same system was rolled out on all MGB’s from 1977 as the engine bay alterations remained for the V8, allowing the 3500cc engine to slot in.

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MGB GT V8 Ignition system

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A Lucas 35D8 distributor was installed on the GT V8; a Lucas ballast coil was mounted on the radiator surround. The firing order was 1-8-4-3-6-5-7-2, with odd numbers on the left-hand cylinders and even numbers on the right.

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MGB GT V8 Gearbox

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The wheels on the GT V8 were unique to this model and were previously supplied by Dunlop; the Centre section was cast alloy, and the outer rim was made of chrome-plated steel. They were the same four-stud pattern as the rest of the MGB range, but the wheel nuts were larger in size and unique to this wheel style. The rim size was 5Jx14, and all had a Centre cap with the MG logo to finish them off.

This particular wheel style was also used on the Jubilee model in 1975 but painted black and gold with a gold MG badge. 175HR-14 radial ply tires were used for the V8 cars. This was the only style of a wheel offered on the MGB GT V8 cars; it was one of the more distinctive signs that the V8 was different from the standard car.

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MGB GT V8 specification details at a glance

Production years 1973 – 1976
Body type GT version only from factory
Engine 3528cc V8
Bore 88.9mm
Stroke 71.1mm
Compression ratio 8.25:1
Engine block Aluminium block
Fuel Twin SU cCarbs
Fuel tank 12 gallons
Max power 137bhp @5000rpm
Maximum torque 193lb ft. @2900rpm
Power to weight ratio 128.4 bhp/ton
Maximum speed 125mph
0-60mph 8.5 seconds
Fuel consumption 22mpg
Gear box 4 speed manual with overdrive
Brakes Discs front and drums rear
Steering Rack and pinion
Wheels – Composite Alloy Centre’s / steel rims 5J x 14
Tyres 175HR 14 radial tyres