1934 Riley Racing MPH Replica



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Riley (Coventry) Ltd was a successful carmaker in the 1920’s and 30’s, having been established in 1898 as a bicycle maker. In 1934 they introduced two similarly styled and gorgeous sports cars into their range: The “Imp” with a 4 cylinder 1100cc engine, and the “MPH” with 6 cylinder engines of 1486c.c. or 1750c.c. During the late 1920’s and through the 1930’s the Company was very active in the racing field, with its racing machines being developed directly from the production cars. Thus, in 1934, racing versions of the sports cars were prepared: four “Ulster” Imps for the T.T. race in the Isle of Mann, and two Racing MPH’s for the Le Mans 24 hour Race in France. The MPH’s were registered for the road in the U.K. as KV9877 (Le Mans race no. 27) and KV9878  (Le Mans race no. 28). Car no 27, driven by Sibilleau and de la Roche, came 2nd overall in the race against the outright winner, a blown 2.3 litre Alfa Romeo, but came 1st in class for cars with engines of up to 1500c.c. Car no. 28, driven by Dixon and Paul, came 3rd overall. A solitary Ulster Imp also ran in the race, coming 8th overall.

The frames for all the MPH’s were based on those of the team cars produced by Riley for the 1933 T.T. race. They were under-slung at the rear, with an 8’- 11/2” wheelbase and a track of 3’-11¾”, with parallel semi-elliptical springs front and rear. Steering was conventional Riley as used on their production cars. The front and rear axles were also of production pattern, but alloy brakes, with cast iron liners, of 15” dia, replaced the plain cast iron brake drums of the production cars. The brakes were operated by the patented Riley continuous cable system used on the production cars. Brake torque reaction rods were fitted to the front axle. Centre lock wire wheels were 19” x 5”. 

An ENV pre-selector gearbox was installed, with a centrifugal clutch, and drive was transmitted to the rear axle by a propeller shaft enclosed in a torque-tube.  Rear axle ratio was 4.77:1. The engines had 6 cylinders, with a capacity of 1486 c.c, and were up-rated versions of the Riley production “12/6” engines of the time.  These had high mounted double camshafts operating overhead valves via short push rods. The combustion chambers were hemispherical, with 1 inlet and 1 exhaust valve per cylinder. The inlet side of the engine had 3 SU carburettors, and the exhaust system had “6 into 1” pipes and a “Brooklands” type expansion box.

Bodies were identical to the Riley Ulster Imps that had been prepared for the 1934 Ulster T.T. race. 

The Racing MPH cars no longer exist. At some point soon after the race they were broken up, and parts used as the basis for other cars. 


Ian Gladstone, an old acquaintance of the owner and proprietor of Blue Diamond Services (Pre-war Riley specialists) in Somerset U.K, was contacted, and enthusiastically agreed to undertake the sourcing of parts and the building of the replica. Over the next two years all the necessary components were gathered or fabricated, and construction began in earnest in late in 2012. By February 2013 the rolling chassis was nearing completion. The car is registered (BON 221) for possible road use in the U.K.


Chassis: Modified 1936 Kestrel to MPH configuration, but with 3 ½” extra in the wheel base to give a little more room for the owner’s 6’-2” frame.

Front Axle and steering:  all components of a 1934 Riley production axle, of correct form and track, with centre lock hubs, were crack tested and refurbished. New bearings, seals and king pins were fitted. Special short springs, well clipped, were fabricated to MPH pattern. Torque reaction rods, to resist axle wind-up under heavy braking loads, were fabricated to original pattern. Shock absorbers are Hartford friction dampers to original pattern and made in light alloy.

Rear axle and torque tube: all components of a 1934 Riley axle casing were tested and refurbished with new bearings and seals, and adapted for the new made racing pattern light alloy axle clamps. Special short springs, well clipped, were fabricated to MPH pattern. The torque tube was shortened to suit, and rear axle ration changed to 4.77:1. New half shafts and rear centre lock hubs were fitted. Shock absorbers are Hartford friction dampers to original pattern and made in light alloy.

Wire Wheels:  correct 19” x 5”, new made to original Riley pattern, and shod with Blockley tyres.

Brakes: new made copies of the special large diameter light alloy brake drums (and associated back plates, shoes etc) as fitted to all the MPH cars (racing and sports). These are cable operated as per Riley production and racing car practice of the day.

Cooling System: original period Riley shell modified to MPH profile, with new original type, new, “vee” profile double matrix core, header tank, stone guard. Original refurbished water pump. 


Block: correct, original Riley 1934 12/6, crack tested and cleaned. Refurbished water pump, and new camshaft drive gear train. Bored for new high compression pistons.

Sump and oil circulation: correct, original Riley 12/6, with new baffles and gauze, and double plunger oil pump 

Crankshaft: original Riley 1934 14/6, crack tested and cleaned, and reground for shell big end bearings. Main bearings are white metal, line bored in situ. Fitted with refurbished friction damper

Connecting rods: correct original 14/6 Riley, crack tested and balanced, and fitted with new small end bushes and shell big end bearings.

Camshafts and valve gear: new made high lift /long overlap camshafts to fast road/race specification, new push rods, cam followers, and refurbished and resurfaced rockers and shafts.

Ignition: Scintilla Vertex magneto, as per original.

Head: correct, original, Riley 1934 12/6, crack tested and cleaned. New valves, guides, and valve springs. 

Inlet side of engine: twin SU HV.2 carburettors on a replica inlet manifold. N.b. A triple carb set-up will also be available as per the Racing MPH.

Exhaust side of engine: as per the Racing MPH, new made “6 into 1” external pipes, with a “Brooklands” type expansion box..

Gearbox: rebuilt Riley 4 speed “Silent Third” type, with all new bearings and seals, a new close ration gear set, and remote control gear-change.  

N.b: ENV pre-selector gearboxes, of the specification fitted to the Racing MPH, was not available. In addition although this type of box is a joy to use, they also sap quite a lot of h.p. in comparison with a manual box. As the Sports MPH was also offered with a manual box, the decision was made to fit one to the project. 

Clutch: Riley single dry plate.

Fuel tank: patterned after an original, rear mounted, with an electric fuel pump.

Body: based on details taken from an original Ulster Imp, with wooden frame and 16swg aluminium alloy skins, and detachable boat tail. Two seats. Cycle mudguards to original pattern.

Auxiliary oil tank under scuttle (not connected). 


Full set of “Jaegar” instruments :

  • Rev Counter
  • Ammeter
  • Oil Pressure
  • Water Temperature
  • Oil Temperature
  • Electrical cut-out switch

Electrical system (12v) 

Dynamo: refurbished ROTAX 2 brush, mounted on front of timing case and directly driven from the engine crankshaft. Electronic voltage regulator, and a 12volt battery mounted in the tool box .

Starter Motor: refurbished ROTAX .

Main headlights: 51/2” Marchal, modified to look like Solara. LED bulbs 

N.b: The Racing MPH was originally fitted with 5” dia. “Solara” headlights. These were found to be ineffectual, and were subsequently not used on any other Riley car.  

Sidelights: Lucas “torpedo” lamps mounted on front wings LED bulbs

Rear lights: combined rear and stoplights, with number plate illumination light. LED bulbs 

ROTAX Ignition and lighting switch  

Panel instrument lights.