Introduced 1933 Number built - 33
In 1932 the MG model range was already quite varied when at the Motor Show that year, several more models were introduced. The already suc-eessful Magna range was complimented by the addition of what was to be known as the K series Magnettes. The cars followed on in logical sequence from the very popular J types and the K1 and K2 utilised the now familiar and well established conventional MG chassis layout. These new models were to form the basis for an important new racing model and it was with this solely in mind that Cecil Kimber took the decision to "produce the K1 and K2, as he could not justify the production of a racing model on its own at the time. The K3 as it was designated did not in fact appear at the same time as the K1 and K2, although it was announced at the 1932 Motor Show. A prototype did however emerge from the factory in January 1933 which would give Kimber his much desired entry into Class G (1100cc) racing as this class fell midway between the 847cc Midgets and the 1271 cc Magnas.
The K types were available at first in two chassis lengths with the K1 having a wheelbase of 9'0" and the K2 being 7' 10", with a track of 4'0" in 'each case. 13" drum brakes provided the stopping power and although the engine was 1087cc it did have more power than its larger engined predecessors, the Magnas. Sporting a cross flow head and stronger crankshaft, the engine at first fitted was known as the KA and was based closely on the six cylinder Wolseley Hornet unit. This was underpowered for the long wheelbase 1<1 and short wheelbase K2, so very soon after the two models had gone into production, a more powerful KB type engine was made available. These engines were put into the open tourers as they were deemed more worthy of the extra power, whilst the more sedate saloons retained the less powerful KA engine. The K1 was offered either as a very attractive pillarless four door, four seater saloon or slightly later as an open four seater. This car could be had with either a four speed 'crash' gearbox or with a Wilson preselector transmission. The K2 was strictly a two seater car and the chassis and body was essentially a widened version of the J2 with the classic cutaway doors and the addition of sweeping front wings completed the package.
The MG model range was particularly confusing at this time with the K series having three different chassis, four different engines, three gearboxes and five body variations and with such small quantities of each one being produced, no two cars seemed alike! As if this was not enough, early on in 1933, the Magna range was updated with the introduction of the L type in which was placed an engine derived from the KB Magnette power unit. This became known as the KC type with coil ignition and twin carburettors. Despite this ever bewildering range of cars, Abingdon did see very good sales during this period, this no doubt helped to justify probably the most famous Magnette of all time, the racing K3.
It was in the winter of 1932 that two K3 prototypes took shape in the racing department at the Abingdon factory, both utilising supercharged 1100cc engines on specially made chassis upon which were mounted modified C type racing bodies. One of the cars .was entered in the Monte Carlo Rally and it proved to be the fastest car on the Mont des Mules hillclimb section, breaking the class record easily. The other car, accompanied by Reg Jackson and a team of drivers, went to Italy to make an entry in the Mille Miglia. This was a gruelling 1000 mile race on public roads which had always been dominated by home teams such as Maserati. The prototype was thrashed around sections of the Mille Miglia course on a reconnaissance mission prior to the event; this was intended to show up any weaknesses in the car and this it did. The pre-selector gearbox had to be revised because the gearing was too low and it also consumed too much oil. Road wheels and hubs were redesigned as were the brake drums which failed under the arduous two month testing. Back in Abingdon, three team cars were prepared and they were shipped to Genoa in early March 1933, ready to tackle the Mille Miglia, driven by Earl Howe and Hugh Hamilton, George Eyston and Count Lurani, with the third car manned by Henry Birkin and Bernard Rubin. Birkin's K3 had to retire with a broken valve, but the remaining two K3s proceeded to break all existing class records, finishing first and second in their class and also collecting the team prize. This marvellous victory at an event that was renowned for being the toughest in the racing world set the stage for countless other successes at race venues all over the world. In its class, the K3 remained at the top for the best part of two years, becoming one of the most successful racing cars of all time.
The two prototype K3s differed from the production K3s in several ways, with the production specification as follows. The standard K2 chassis of 7'10 3/16" was employed based on an open channel frame stiffened with tubular cross members and cruciform centre bracing which was under slung beneath the rear axle. Remote chassis lubrication was provided by grouped oil nipples mounted on a plate on the offside bulkhead. Suspension was by semi-elliptic leaf springs front and rear, running flat under load and being taped and then cord bound. The main spring leaves moved in sliding trunnions at the trailing end. Two Hartford duplex friction dampers were mounted longitudinally at the front and four were utilised at the rear, mounted transversely. Wheels were of the Rudge Whitworth wire spoked racing type, 19" in diameter. Brakes were.13" drum type, cable operated via a central cross shaft connected to a fly-off type handbrake lever. The brakes were adjustable from the cockpit via a small hand wheel mounted on the back of the gearbox below the preselector lever. Steering was effected by means of a cam type box and transverse draglink to an axle mounted slave arm that controlled the wheels through a divided track rod.
Initially the 1933 cars carried a 23V2 gallon slab type fuel tank with a 3 gallon reserve and twin quick release racing filler caps. There were twin electric fuel pumps, one main and one reserve feeding into a single SU carburettor mounted atop the Powerplus vane type supercharger. A KiGass fuel priming pump was mounted on the right hand side of the dashboard to assist cold starting. The cars were modified in 1934 to include the provision of a 271/2 gallon fuel tank formed into a pointed tail and a handpump was incorporated to maintain fuel supply by air pressure in order to dispense with the need for a battery. The original specification electrical system included a magneto, firing 14mm sparking plugs, a dynamo charging twin 6 volt batteries, headlamps, torpedo side lamps, tail lamps, twin horns and a windscreen wiper. All these circuits were separately switched and fused. The later 1934 cars carried special external contacts to couple up to auxilliary starter batteries. Instrumentation was comprehensive with a large 6" diameter Jaeger tachometer, oil pressure gauge, oil and water thermometers, fuel gauge, oil tank gauge, ammeter, supercharger boost gauge and supercharger oil pressure gauge. The fitting of the manual handpump on the later cars necessitated the supply of a fuel supply air pressure gauge, and on these cars the fuel gauge and oil tank gauge were removed.
The 6 cylinder overhead camshaft K3 engine had a bore and stroke of 57mm x 71 mm and a displacement of 1086cc. The four main bearing crankshaft carried steel connecting rods with aluminium pistons. Engine lubrication was effected by a wet sump system utilising a gear driven pump and a large triangular shaped finned sump assisted with the oil cooling. A reserve oil feed tank was mounted on the scuttle. The cylinder head was of the cross flow type with a single overhead camshaft driven by a vertical shaft directly from the crankshaft. This shaft also formed the armature for the vertically mounted dynamo. Special valves and triple springs were used on both inlet and exhaust and the bearings all had special metalling applied. The Powerplus vane type supercharger was mounted ahead of the radiator and ran at 75% of crankshaft speed, driven from the crankshaft nose via a splined coupling shaft with universal joints. This ran with a high boost pressure, the end result being a power increase of nearly three times that of the standard engine. Peak figures quoted for the engine show 118 bhp @ 6000rpm with the Powerplus supercharger and on the 1934 engines fitted with the Marshall Roots supercharger 115bhp@ 6500rpm. These later engines had an improved N type cylinder head with more efficient porting, giving smoother and more progressive power through the range. A Wilson preselector gearbox with centrally mounted selector lever transferred the power to the road wheels via a three quarters floating rear axle with a straight cut bevel final drive. The exhaust system was a Brooklands competition system with a six branch primary manifold feeding an externally mounted silencer which then led to a huge fishtail tailpipe. Engine cooling was by means of a thermo syphon system and engine driven water pump with a stone guard protected radiator featuring a quick release competition filler cap.
Brief technical specifications…
Engine: 6 cylinders in line.
Bore/Stroke: 57mm x 71 mm
Valve operation: Overhead camshaft.
Compression ratio: 5.4:1 to 6.6:1 according to tune.
Carburation: Single SU carburettor with Powerplus or Marshall Supercharger
Power output: 105 to 125bhp according to state of tune.
Transmission: Wilson pre-selector four speed gearbox without clutch.
Brakes: 13" drum, cable operated, (twin lever 1934)
Suspension: Half elliptic front and rear with sliding trunnions. Beam axle front, live rear axle.
Chassis: Twin side members with cross members.
Wheelbase: 7' 10 3/16"
Track: 4' 0" front and rear.
Wheels: Centre lock wire spoke.
Weight: 181/4 cwts.
Performance: Max speed: 110 mph.
Acceleration: 0-75 mph in 14.6 secs.
Fuel consumption: approx. 15 mpg.
Number built including prototypes and EX135: 33
Price new: £675 for chassis only or £795 complete.
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