The MGB GT V8 was powered by the all-aluminium Rover 3528cc V8, an engine with an unusual history. Originally a Buick V8 design from the early 1960s, it was acquired under licence by Rover after Rover's then-Managing Director William Martin-Hurst encountered the redundant aluminium block on a visit to the United States in 1963. Rover put their version into production in 1967 in the 3.5-litre saloon, with later applications including the Range Rover, SD1, Land Rover and Discovery. After the merger of MG with Rover under British Leyland, the engine was adapted for use in the MGB shell and entered series production in the V8 from April 1973 to July 1976.
Engine Specification
The cylinder block is sand-cast aluminium with cast-iron dry cylinder liners. The cylinder heads are die-cast aluminium with iron valve guides and valve seat inserts. Bore is 88.9mm and stroke 71.1mm, giving a swept capacity of 3528cc. Compression ratio is 8.25:1, producing a quoted 137bhp DIN at 5000rpm.
The complete engine weighs approximately 320lb, around 40lb less than the four-cylinder cast-iron MGB B-series unit. This engine-weight saving is one of the V8's most important characteristics: front-to-rear weight balance is improved over the four-cylinder MGB despite the larger displacement, and the modest weight increase versus the MGB 1800 was a key reason MG was able to fit the V8 within the standard MGB bonnet line without a bonnet bulge.
Engine Numbering and Identification
Following the Rover system, all factory MGB GT V8 engines have eight-figure numbers without any letter prefix, beginning 4860. Genuine V8 engines are numbered in the main series 48600001 to 48602596. The number is stamped on a plate at the rear of the cylinder block, on the left-hand (passenger) side near the bellhousing flange. Many other Rover V8 engines from later applications, Rover P5B, Rover SD1, Range Rover, Land Rover and aftermarket builds, share the same external architecture and frequently appear under MGB GT V8 bonnets, but only 4860-prefixed engines are original to the car.
The distinction matters for authenticity, valuation and parts compatibility, particularly with regard to the camshaft profile, distributor drive gear and inlet manifold arrangement.
V8-Specific Engineering
Although the Rover V8 architecture is widely used, the V8 engine as installed in the MGB GT V8 has several factory-specification details that distinguish it from later Rover V8 variants. The carburettor arrangement uses twin SU HIF6 instruments mounted at the rear of a two-piece inlet manifold (a Rover penthouse base topped by a V-shaped MG-specific adaptor) rather than the four-barrel SU/Stromberg/Holley arrangements of later applications. The exhaust manifolds are cast-iron, exiting at the rear of each cylinder bank where they immediately join a single downpipe per side. The oil filter is mounted remotely, on the right-hand inner wing rather than directly on the engine, with steel pipework connecting it to the engine block.
Cast-aluminium rocker covers carry MG logos rather than the Rover-style covers found on later cars. Pistons and main bearings are MG-specific and not interchangeable with Rover-spec parts.
Production Changes
Several engine-related production changes occurred during the V8's three-year production run. Pre-production began at car number V8 101 in December 1972, with series production starting at V8 124 in April 1973. The oil gauge plumbing was revised at V8 1149 in November 1973, with the gauge feed taken from the oil pump cover instead of the oil filter for improved cold-start reading. Heat shields for the spark plug leads were added to the four middle cylinders at V8 1956 in September 1974, and to the two front cylinders at V8 2266 in February 1975.
The oil pressure gauge calibration was revised at V8 1825 in June 1974. Final V8 production ended in July 1976.
Sub-Sections
Complete and reconditioned engines are listed under Engines. Lower Engine and Upper Engine sections cover the block, crankshaft, pistons, valvetrain and timing components. Cylinder Head, Engine and Gearbox Mountings, Engine Controls, Oil Filtering, Oil Cooler and Hoses, and Water Pump and Thermostat each cover their respective subsystems in detail. Lubrication and Paint covers classic-grade engine oils with appropriate ZDDP content for the V8's hydraulic-tappet valvetrain (factory-fitted from new, unusual on British engines of the period), alongside engine paints.
Performance options are listed under Upgrades and Alternatives.
MGOC Spares
MGOC Spares carries a comprehensive range of MGB GT V8 engine components, see individual sub-sections for detail.