Note: This information will hopefully be updated and expanded by Neil Cairns. This information currently mostly pertains to the Mk. III.
The in-line four cylinder, overhead valve engine feeds its power into a normal friction clutch, then into a four speed, three synchromesh gearbox. An open propeller shaft takes the drive to a banjo rear axle supported on leaf springs. Pretty standard 1950's and 1960's car technology, and all normal BMC components, virtually identical with the MGA and early MGB Sportscar. The cars age is shown by there being grease nipples on many components, requiring attention every 1000 miles.
Four cylinders; bore 73.025 mm. (2.875 in.), stroke 88.9 mm. (3.5 in.) cubic capacity 1489 c.c. (90.88 cu. in.); compression ratio 8.3:1; overhead valves operated by push-rods from a 3-bearing chain-driven camshaft; 3-bearing counterbalanced crankshaft; aluminum-alloy pistons; renewable-element full-flow oil filter.
This is again, all MGA. These transmission have a famous characteristic of whining loudly in first and reverse. These cars have short-lived second gear synchros. Mine pops out of fourth sometimes when it is cold out. Basically though these gearboxes are invicible.
Single-Plate dry clutch with hydraulic actuation; 4-speed with synchromesh on second, third, and top gears, giving overall ratios of -- first 15.64, second 9.52, third 5.91, top 4.3, and reverse 20.45:1; central floor gear change; Hardy-Spicer propeller shaft with needle-bearing universal joints; three-quarter-floating rear axle with hypoid final reduction gears--axle ratio 4.3:1.
Outwardly a typical SU setup here except these are much larger than what you would find on an MGA. They are actually SU HD4 1.5. For those not familiar, they are huge for SUs. These twin linked carbs have lots of aluminum and brass to polish here, and it looks wonderful. Rover, Jaguar and Rolls-Royce used a similiar setup. The air filter is also very different from todays. Instead of a paper element, a wire mesh is set in a pan of oil to trap dirt as it passes through. Sort of a pre-historic K&N job. A rather neat cast aluminum airway leads from the air cleaner to the carbs, and it looks like a 50's vaccum cleaner!
Twin S.U. automatic downdraught carburettors fed from rear tank by rear-mounted S.U. electric fuel pump; oil bath air cleaner and silencer; fuel tank capacity to 10 Imperial gallons (45.4 litres, 12 U.S. gallons); concealed fuel filler with lock.
Cooling and Ignition:
Very familiar territory here. Radiator is made by Morris Radiators and looks like an overgrown MGA version. Replacement is possible but don't expect it to look right. Old units are sturdy and can be rebuilt. The ignition is common Lucas parts and should cause any trouble.
Cooling and Ignition Data:
Cooling by pressurized system assisted by impeller pump and fan; circulation thermostatically controlled.
Ignition by battery and coil; automatic advance and retard with centrifugal and vacuum control.
This car has drum brakes on all corners. When in proper condition they will stop the car without any trouble, and no servo is needed. The cars can be converted to Austin-Healey disc brakes.