Skip to content
MOTRS

MGB GT

1965-1980 / Coupe / United Kingdom

// FAQ

What is the difference between a chrome bumper and rubber bumper MGB?

The chrome bumper MGB (1962--1974) has slim chrome-plated steel bumpers, a lower ride height, and (in most markets) twin SU carburettors producing 95 horsepower. The rubber bumper MGB (1974.5--1980) has large polyurethane-covered impact absorbers, a ride height raised by 37mm to meet US bumper height regulations, and a detuned engine producing 84 horsepower with a single Zenith-Stromberg carburettor.

The chrome bumper car is the more desirable variant, with better handling (lower centre of gravity), more power, and cleaner styling. Rubber bumper cars are significantly cheaper and many owners reverse the modifications -- lowering the ride height, fitting twin SU carburettors, and sometimes even converting to chrome bumpers. If budget is a concern, a well-sorted rubber bumper car with these modifications delivers nearly the same experience as a chrome bumper car for 30--40% less money.

Is the MGB Roadster or GT better?

It depends entirely on what you want. The Roadster is the quintessential British sports car experience -- wind in your hair, sun on your face, the sound of the engine bouncing off hedgerows. It is the more valuable car and the one most people picture when they think "MGB."

The GT is arguably the better car to drive. The fixed roof significantly stiffens the body, improving handling and reducing the scuttle shake that plagues the Roadster on rough roads. The GT has a practical hatchback, a more refined interior, and is usable year-round without worrying about weather. The Pininfarina roofline is, to many eyes, more beautiful than the Roadster.

If you want touring capability and all-weather usability, buy the GT. If you want the classic open-top experience and don't mind getting rained on occasionally, buy the Roadster.

Can I daily drive an MGB?

Yes, with realistic expectations. A well-maintained MGB is a reliable car by 1960s standards. Thousands of them were daily driven for years. The B-series engine is robust, parts are cheap and plentiful, and the car is mechanically simple enough for owner maintenance.

The caveats: no air conditioning (unless retrofitted), no power steering, basic brakes by modern standards, a soft top that leaks when old, and an electrical system that rewards vigilance. You will get wet in the rain. You will be slow merging onto motorways. You will not have a crumple zone worth mentioning.

Budget for occasional downtime. Carry spare ignition components. Fit an electronic ignition conversion. Upgrade the cooling system. Accept that an MGB is not a Toyota Corolla -- it requires attention and rewards care. Many Australian owners use their MGB as a second car for weekend drives and sunny commutes, which is probably the ideal arrangement.

How bad is rust on an MGB?

The MGB is notorious for rust. The monocoque body has numerous water traps, double-skinned cavities, and poorly drained areas that corrode from the inside out. After 50+ years, even Australian-delivered cars with no salt exposure will have rust somewhere.

The critical areas are the sills (structural box sections that carry bending loads), floor pans, A-posts (windscreen pillars), inner wings around the suspension turrets, and rear spring hangers. Sill replacement is the most common major repair -- if a car hasn't had it done, it probably needs it.

The good news: repair panels for every rust-prone area are available off the shelf. British Motor Heritage panels are generally excellent quality. A competent welder can repair even severely rusted MGBs, though the cost can exceed the car's value if the rot is extensive. Always inspect underneath, lift the carpet, and bring a magnet.

What engine oil should I use?

20W-50 mineral oil for normal driving conditions. The B-series engine was designed for mineral oil and runs perfectly well on it. Synthetic oil is unnecessary and can cause leaks through old cork gaskets that mineral oil doesn't penetrate.

Oil capacity is approximately 4.5 litres including the filter. Change every 5,000 km or every 6 months, whichever comes first. Use a quality filter -- the spin-on type (later cars) or cartridge type (early cars).

Are SU carburettors difficult to maintain?

SU carburettors are actually simpler than most alternatives. They have fewer moving parts than a Weber or Solex, and the operating principle is elegant: a piston that rises and falls in response to engine demand, varying the jet area and therefore the fuel flow. Once you understand how they work, tuning becomes intuitive.

The key maintenance items are: top up the damper oil (every 3,000 km, takes 30 seconds), check and adjust the mixture (once a year or when symptoms appear), and replace the needle and jet when worn (every 40,000--60,000 km). A full SU service kit costs $30--50 per carburettor.

The most common SU problem is throttle shaft wear. When the brass bushings in the carburettor body wear, air leaks in around the shaft, making it impossible to set the mixture correctly. This requires rebushing -- a specialist job at $50--100 per carburettor.

Should I fit electronic ignition?

Yes, unequivocally. An electronic ignition conversion (Pertronix, Powerspark, or Accuspark -- $80--150) replaces the contact breaker points and condenser with a solid-state trigger. It fits inside the existing distributor and is invisible from outside.

The benefits: no more points adjustment, no more condenser failures (the number one cause of MGB roadside breakdowns), more consistent spark timing, slightly better fuel economy, and improved starting. The only downside is a minor loss of "originality" that is invisible to anyone who doesn't open the distributor cap.

If you want to keep the car 100% original for concours judging, keep the points -- but carry spares. For everyone else, electronic ignition is the single best upgrade you can make to an MGB.

What is the MGB GT V8?

The MGB GT V8 was a factory variant produced from 1973 to 1976, fitting the Rover 3.5-litre aluminium V8 engine (derived from the Buick 215) into the GT body. It produced 137 horsepower and 263 Nm of torque -- a massive increase over the 1.8-litre four-cylinder.

The V8 engine is lighter than the B-series four, so the weight distribution is barely affected. The car feels transformed -- effortless acceleration, a wonderful exhaust note, and the ability to cruise at motorway speeds with the engine barely working.

Only about 2,591 were made, all in GT form (no factory V8 Roadster), and none were officially exported to America. Prices today are $50,000--80,000 AUD and climbing. Owner-built V8 conversions are common and can be done for $10,000--20,000 using a Rover V8 from a Range Rover or SD1.

How much does it cost to restore an MGB?

A rough guide for an Australian restoration:

  • Light restoration (mechanically sound car needing bodywork and cosmetics): $15,000--25,000
  • Medium restoration (car needing sill replacement, engine refresh, full respray, new interior): $25,000--40,000
  • Full restoration (bare-shell rebuild, everything new or rebuilt): $40,000--60,000+

A professional bare-shell restoration can cost more than the finished car is worth on the open market. This is the classic car paradox -- restoration is rarely a profitable exercise. Buy the best car you can afford rather than a cheap car that needs everything.

Is the MGB a good investment?

The MGB has appreciated steadily over the past two decades, particularly chrome bumper Roadsters and GT V8s. However, the sheer number of MGBs in existence (hundreds of thousands worldwide) means appreciation is slower than for rarer sports cars.

Chrome bumper Roadsters in good condition are solid holds -- they're unlikely to lose value and will appreciate gently. GT V8s are genuine investment pieces with strong demand and genuine scarcity. Rubber bumper cars have appreciated least and may not keep pace with inflation.

Buy an MGB because you want to drive it. If it appreciates, that's a bonus. If you want a classic car as a pure investment, there are better options.

Can I use an MGB for weekend touring?

Absolutely -- this is what the MGB was designed for. The boot is a reasonable size (the Roadster can fit two soft bags or one proper suitcase), the seats are comfortable for 3--4 hour stints, and the car cruises happily at 100--110 km/h. With overdrive, highway cruising is relaxed and economical.

The GT is even better for touring -- the hatchback swallows a surprising amount of luggage, and the fixed roof means you don't need to worry about weather.

Plan your route with fuel stops every 250--300 km (the tank is 54 litres, economy is 9--12 L/100 km). Carry basic tools, a spare fan belt, spare ignition components, and a litre of oil. Join a roadside assistance service that covers classic cars.

What fuel does the MGB use?

Standard unleaded 91 RON or 95 RON is fine for most MGBs. Engines with hardened valve seats (most post-1970 cars and all rebuilt engines) can run on unleaded without issues. Pre-1970 engines with original soft valve seats may benefit from a lead replacement additive, though the evidence is debated.

The B-series engine is not fussy about fuel quality. Avoid E10 (ethanol-blended) fuel if possible -- ethanol attacks old rubber fuel lines, carburettor seals, and fuel pump diaphragms. If you must use E10, replace all fuel system rubber components with ethanol-resistant alternatives.

What are the most important spares to carry?

For any drive longer than a trip to the shops:

  1. Spare ignition condenser (unless you've fitted electronic ignition)
  2. Spare rotor arm
  3. Spare fan belt
  4. A litre of engine oil
  5. A litre of coolant
  6. Spare fuses (a selection of the correct ratings)
  7. Basic tool kit (spanners, screwdrivers, pliers, a wire brush)
  8. A torch (for diagnosis in the dark)
  9. Lucas wiring diagram (laminated, in the glovebox)

This sounds like a lot, but it all fits in a small canvas bag in the boot. Most of these items weigh almost nothing and will save you a tow truck call.

How does the MGB compare to a Triumph TR6?

The TR6 is a larger, more powerful car with a 2.5-litre inline six, a more muscular character, and a rawer driving experience. The MGB is lighter, more nimble, and more refined. The TR6 wins on straight-line speed and engine character. The MGB wins on handling balance and parts availability.

The TR6 is more expensive to buy and maintain. Its separate chassis means less corrosion vulnerability in the body, but the chassis itself can rust. Parts are available but not as comprehensively as for the MGB. The TR6 fuel injection system (PI) on UK-spec cars is complex and expensive when it fails.

Choose the MGB for a balanced, accessible, well-supported sports car. Choose the TR6 for a more visceral, muscular experience with a wonderful six-cylinder engine.

Is the 3-main-bearing engine a problem?

The early B-series engine (1962--1964 MGBs) used a three-main-bearing crankshaft, while all later cars used a stronger five-main-bearing design. The 3-main-bearing engine is not bad -- it was used successfully in the MGA and other BMC cars for years -- but it is less robust under sustained high-RPM driving and more prone to crank flex.

For normal road use, a well-maintained 3-main-bearing engine is perfectly adequate. For any form of spirited driving or competition, the 5-main-bearing engine is significantly better. If you're buying an early car, budget for a potential engine rebuild and consider fitting a 5-main-bearing crank at that time.

Can I increase the MGB's power?

Yes, and the B-series engine responds well to tuning. Common upgrades include:

  • Carburettor swap (rubber bumper): Replace the single Zenith-Stromberg with twin SU HS4 carburettors. This alone restores 10--15 hp.
  • Cylinder head work: Porting, polishing, and a mild performance camshaft can add 15--20 hp.
  • Exhaust: A tubular exhaust manifold and free-flowing exhaust system add 5--10 hp.
  • Weber DCOE conversion: Twin Weber 45 DCOE carburettors on a proper manifold are the classic performance setup, adding 20--30 hp but requiring careful jetting.
  • Engine rebuild to fast-road spec: Overbored, balanced, with a performance camshaft, the B-series can make 120--130 hp -- a dramatic improvement over the standard 95 hp.
  • V8 conversion: The ultimate power upgrade. A Rover 3.5 V8 fits the engine bay and adds 40+ hp with far more torque.

For most road use, a carburettor swap, mild head work, and a good exhaust are the sweet spot -- meaningful improvement without reliability compromises.

Got a question we haven't covered?

Ask your MGB GT question and we'll add the answer to help future owners.

Submit a question

This guide took hours to research. If it helped, consider buying us fuel.