RM models

Riley RM Models

RMA – F and specials information supplied by Gwyn Morris; RMH/Pathfinder by David Rowlands


1945 – 1952

The RMA was the first Riley car to be manufactured after World War 2, introduced in 1945. A stylish and comfortable 55 BHP saloon for the post war period.

Chassis numbers: 35S 10001 – 39S 16375

When it was announced to the public via the motoring press in August 1945 it was also referred to as the “New Riley Twelve”. Whilst development had been planned prior to the Second World War, the Riley factory and Design Office had been badly damaged during the conflict; therefore a completely redesigned model would emerge, ahead of the competition. It would continue the Riley pedigree of advanced design and performance, aimed at the discerning professional.

It was a sleek 4-door Saloon body, with seating for 5 people. It had a 4 cylinder 1496cc engine of the traditional Riley crossflow, high twin-cam design, driving through a 4-speed gearbox and torque-tube axle, with 16” wheels. The rigid steel-frame chassis supported the low-slung coach-built body which sported a “leather top” roof covering, opening split windscreen, leather seating (occasionally with Bedford Cord inserts) and a large boot by the standards of the day.

The rear suspension was via a pair of semi-elliptic leaf springs with anti-roll bar and lever-arm hydraulic dampers, whilst at the front the IFS employed double wishbones, longitudinal torsion bars and telescopic shock absorbers. This set-up together with an advanced rack and pinion steering unit gave the car exceptional road holding not surpassed until the modern era. Brakes were Girling Hydro-mechanical 10” diameter drums.

It was initially priced at £555 (+ purchase tax = £710) and when production got properly underway in 1946, competed with other manufacturers of well-appointed sporting Saloons, although by 1949 the price was £714 (+ purchase tax = £913.)

Most easily identified by white-faced instruments, the production at the Riley factory at Foleshill, Coventry, increased steadily, with only minor internal trim changes through to 1949, when after the production of 6375 1½ litre cars, production was transferred over to the other “Nuffield” factory at Abingdon, alongside the MG production line.

1949 – 52 “1½ Litre Saloon” (Latterly known as the RMA) – Abingdon
Chassis numbers: 39S 16376 – 42S 20504

The 1½ Litre Saloon had been produced at Coventry very successfully with just a few minor styling changes along the way, and so when the production was transferred to Abingdon, the opportunity was taken to revamp and improve its appeal. At first it was the interior that was changed, this being carried out in stages to include a redesign of the front floor-board panels, a revised dashboard that sported gold–faced instrumentation and veneered door window cappings that included ash-trays. Once the “fully-modernised” body was in full production the opening drivers side portion of the V windscreen was deleted. The design of the pleated leather seating was changed, with an option of different coloured piping and the switch layout, control knobs and wiper motor operation was altered.

The performance and layout of the 4 cylinder 1496cc engine remained unaltered throughout most of this period, with only the radiator becoming pressurised. The 10” diameter Girling Hydro-mechanical drum brakes continued, as did the steering, with just the suspension being upgraded by the fitting of telescopic shockers at the rear.In June of 1952 the engine received an upgrade to the valve-train and camshafts/timing that altered the “tappet” setting. Performance appeared not to be improved, with a maximum of around 75 mph and a comfortable cruising speed of 55 -60 mph, with fuel consumption in the region of 26 – 32 mpg.

Paint colour options were extended, and included some “Metallichrome” finishes and then from October 1951 the chromed bumper set-up was upgraded to include twin cross-rails and larger over-riders at the rear and a full width bumper at the front including twin small over-riders.

Production figures over this period (total = 4160) had unfortunately started to decline, and with the home market price still being £714 (+ purchase tax = £913), a revitalisation was planned. Ongoing talks between Nuffield and Austin had formed an alliance that was to become BMC and it was at this point that the models were to be designated with a new reference. The 1½ Litre Saloon was now, retrospectively, to be known as the “RMA”.


1946 – 1952

The RMB is a powerful post-war 2½ litre sporting saloon that provides performance and comfort in a high standard coach-built body, that will turn heads everywhere.

Chassis numbers: 56S 2001 – 59S 4311

After the successful launch of the 1½ litre Saloon (RMA), the 16 hp 2½litre Saloon was announced to the public in the Autumn of 1946. The more powerful 90 BHP 4 cylinder 2443 cc engine was fitted to a heavier and longer chassis and the smooth styling of the body was further enhanced by the longer bonnet. The remaining body structure was the same as the 1½ litre. This 4-door, 5-seater model was trimmed with pleated leather seating (occasionally with Bedford Cord inserts) ; the doors had polished wood cappings to “Rexine” trimmed door panels. There was excellent visibility all round, with a “V” windscreen, opening on the driver’s side. Carpeting  that matched the trim colour and wool union headlining was of good quality, and the white-faced Jaeger instrumentation in the stylish dashboard gave an overall feeling of opulence.

Drive was through a 4-speed synchromesh gearbox via a torque-tube axle and 16” wheels, giving a top speed of just below 100 mph and a comfortable cruising speed of over 65 mph, resulting in a fuel consumption of 18 -22 mpg. The engine was upgraded to 100 bhp from May 1948. The handling and ride, developed from the Riley pedigree of sporting success, was improved due to the incorporation of torsion-bar front suspension and rack and pinion steering. This, together with large Girling hydro-mechanical brakes and the positive feel of the rear end via the longitudinal semi-elliptical leaf springs and anti-roll bar, gave a performance that was second-to-none at the time and proved worthy of praise in competition and rallies.

It was initially priced at £880 (+ purchase tax = £1125) , but in early 1949 had risen to £958 (+ purchase tax = £1225).  Production over the first 3 years from Coventry was 2314 with the emphasis being on the export market; from 1948 they were available in  left-hand-drive version. Being in the upper price bracket, the competition with similar manufacturers such as Armstrong Siddeley, Alvis, Jaguar, etc was fierce.  Whilst the majority of cars were finished in black cellulose (with brown internal trim), after 1947 they were offered with a limited alternative range of colours. From October 1948 a choice could be made from  Black, Maroon, Green or Ivory, with suitably matching or contrasting interiors.

1949 – 52 “2½ litre Saloon” (Retrospectively known as the RMB) – Abingdon
Chassis numbers: 59S 4312 – 62S 9910

When the decision by the Nuffield Board had been made to transfer production from Coventry to Abingdon, the opportunity seemed right to upgrade and further enhance the models. At first, from around May 1949, a “half-modernised” style was introduced, where the earlier style of dashboard (with white-faced instruments) was kept, whilst the door trim panels and cappings were revised. The “fully modernised” version was soon to follow and the dashboard was completely restyled, to include gold-faced instruments and non-opening windscreen. The steering wheel type changed from the black-plastic-coated aluminium rim  round-spoked version to the Bakelite-rimmed square-spoked version, originally in a pinkish Ivory but later in mottled brown.

Mechanically, there were no immediate specification changes, but during this period modifications and upgrades were carried out to the shock-absorbers and  brakes, and the cooling system was pressurised.
At the end of 1951 there were a series of upgrades to the engine, now designated as the RMB2, which included alterations to the cylinder-head, cooling and front mounting method. This is most easily identified by this type of engine having only a single drive-belt for the dynamo and fan pulley arrangement. Previously a second smaller belt had been fitted to drive the fan pulley.   Externally, the leathercloth roof covering remained unchanged and the choice of paint colours was further expanded to include “Metallichrome” finishes in Sun-Bronze, Almond Green, and Silver-streak Grey.

The front and rear fully chromed bumper set-up was revised in October 1951, to give  a 3-piece full bumper at the front and larger over-riders at the rear that supported twin cross-rails.

Production over this period had increased to a total of around 5520, with the highest yearly total in 1950 of 1616 cars, with two-thirds being exported. The exceptional performance of the “Big-Four” engine, combined with the outstanding handling and styling, meant that this model was well suited to the long and open roads of Australia and the USA, whilst at home it could still outrun most of its rivals. This was recognised by many UK police forces, who kept fleets of 2½ litre Rileys as their preferred means of patrolling the roads.
The home market price was held static over this period at £958 (+purchase tax = £1225), which limited sales to those more “well-to-do”.


1948 – 1950

This large 100 H.P. “Open Sports 3-Seater” gives “Magnificent Motoring” and exceptional performance, with large fuel tank and spacious luggage capacity for long distance care-free driving.

Chassis numbers range: 58SS 2802 – 612S 7632

At its introduction to the public via the pages of the “Autocar” magazine in March 1948 this variation of the post-war Riley was referred to as the “Sports 2½ Litre”, but subsequently has been known by no fewer than 9 other names! The design of an open sports model had been developed as the result of a mission to the USA in 1947 to investigate the demand for such a model. The result was a larger bodied open sports tourer, with ample room for three persons via a wide, pleated leather clad bench seat and having a large capacity boot, an increased capacity fuel tank, full weather equipment and having sleek-lines all garnished with heavy chrome plating.

The dashboard was specific to the model and a passenger grab-handle fitted above. Brighter paint colour options were expanded to include Scarlet, Ming Blue, (Clipper Blue), Green and Ivory, as well as Black, Metallichrome Almond Green and Autumn Red.  The chassis was basically that of the Saloon cars but with modifications at the rear end to support the 20 gallon fuel tank and the rear mounted spare wheel, together with altered jacking tubes. All engine, transmission, brakes and steering were the same as the 2½ Litre Saloons, with lighter rear springs and a revised exhaust system.The aluminium bonnets were lowered by 2” and the windscreen could be folded down flat. The steering wheel position was offset by approx 3” toward the drivers door via the fitting of an intermediate reduction gearbox in the column, and there was a column mounted gear change lever, giving the centrally seated passenger more room for their legs. The large boot lid was aluminium skinned to aid lifting, but the doors were steel, as was the rest of the body.

The prototypes had been of left hand drive layout which had meant alterations to the engine exhaust manifold and to the pedal control detail, but the body was easily converted for RHD models.  Production was slow to get away and for the first year almost all sales were to go to export. It wasn’t until September of 1949 that cars were available on the home market, where they were priced in line with the 2 ½ Litre Saloon cars, i.e. at first £1125 and then £1225 (both including purchase tax) in 1950. It was planned that 500 cars were to be built, of which 92 were built in Coventry after which the remainder of production came out of Abingdon. The final six cars, built at the very end of Dec 1950 were given 61 2S prefixes to their chassis number as they would not be sold until 1951.

The chassis designation of the 3 Seater Sports was “SS”, but when the gear-change was amended to a floor shift (after public demand), the designation became “2S”, i.e. 2 Seater, even though the bench seat remained. At the time of the formation of BMC, the model was given a retrospective reference as the “RMC”, but has always been fondly known as the RM “Roadster”.


1949 – 1951

With speed that exhilarates and comfort that delights, the 2½ litre Drophead Coupé gives dignity of appearance and provides quick convertibility to open-air freedom, whilst being “As modern as the hour”.

Chassis number range: 59D 5006 – 61S 8197

The 2½ Litre Drophead Coupé was designed to appeal to those that yearned for the pleasures of open-air driving in a quality produced car which had ample performance and a sporting pedigree, with adequate room for 4/5 persons, full weather equipment and sleek 2 door styling. So after the final prototype had been displayed at the 1948 Motor Show, it was introduced soon after the move to Abingdon in the autumn of 1949, (Chassis designation “D”) in both RHD and LHD format, with the proven 100 BHP 2½ Litre engine and transmission as its basis.

Prototypes had been developed early in Coventry production in both 1½ and 2½ Litre form, but only the larger engine car would go into production. Some minor modifications had been necessary to the standard 2½ Litre chassis, with altered body support plinths and underfloor battery box bracket. All suspension, brakes, steering, electrics etc were as the Saloon models.

The large aluminium skinned doors gave access for the rear passengers via fold-down front seats and the easily erected hood/frame stowed away behind the back seat into a metal box in a suitably modified Saloon body rear end. The rear side panels included the trafficators and fully wind-down window glasses. The appearance of the front of the car was similar to the Saloon but with the screen header exposed and now slightly changed from the narrower prototype version, such that the chrome quarter- lights affixed to the doors, closed snuggly to provide buffeting protection at speed.

Production of the sanction of 500 cars continued in batches of both LHD and RHD form through 1950 and up to June 1951, with only minor modifications. Scuttle vents were added and after a factory scheme was developed for an upgrade to the roof, the wooden framed rear window was deleted in favour of a chrome framed one, that helped to stow away the top more neatly. The hood frame was braced by external chromed landau-bars, topped with a nailed-on Mohair material which in virtually all cases was Beige in colour, and fully lined with Wool-union or Dobby.

The price in 1949 was £995 (+ purchase tax = £1272) with only a small reduction in 1950/51. Paint colours that were offered included, Black, Autumn Red, Almond Green/(Met), Sun Bronze(Met) and Ivory, with other “specials” such as Scarlet and Clipper Blue. The dashboard was fitted with the gold faced instruments as per the Saloon and the “Riley patented Air conditioning unit/heater” was standard. With a floor-change gearstick and optional tachometer, the Drophead Coupe, or RMD as it was to be designated later after the formation of BMC, was to become an export success, particularly in the USA and other warmer climate countries.



1952 – 1955

This well appointed 1½ litre RME Saloon with upgraded brakes and rear-axle provides elegant motoring and an appearance that thrills with economy and style. Later re-styled to become the “New Look-Re-styled RME”.

1952-55 1½ Litre RME Saloon   Chassis numbers: RME 42S 20505 – RME 21854

The main result of the Nuffield/BMC plan was the proposed upgrading of both the 1½ & 2½ Litre Saloons. The designation “RME” was given to the 1½ Litre Saloon that was now to undergo a complete change to the braking and final drive system. The original 4.89:1 ratio Riley type torque-tube/spiral-bevel axle was replaced with a 5.125:1 Nuffield hypoid-bevel axle, together with an open prop-shaft. This necessitated a revision to the rear spring location and to the mounting of the intermediate prop-shaft. The braking system was changed to a Girling fully hydraulic set-up with twin leading-shoes at the front.

As a result of the axle ratio difference, the top and cruising speeds were reduced by about 7%, but acceleration in lower gears improved, the overall effect being a slight increase in fuel consumption.
Introduced in late July 1952, the body specification initially remained the same as the last of the RMA’s, i.e. still with the Black leather-cloth roof covering, running boards, and headlights in separate nacelle pods, but soon a larger rear window with chromed trim surround was to be fitted and the pleated leather seats were revised, to have a broader back with flat tops. The rear window blind that had been fitted to all previous Saloon models was now gone and substituted by a dipping rear-view mirror. All other trim, external and internal, remained the same. The last of this running-board style of RME left the Works in September 1953.

The available paintwork colours were limited to Black, Autumn Red, Woodland Green and Silver Streak Grey, and in line with most other manufacturers the price had risen slightly to £860 (+ purchase tax = £1339). This was partly due to a hike in the purchase tax rate and whilst overall production figures over this period were down, (to around 1320 cars), compared to the previous couple of years, there were more cars in the showrooms due to a decrease in export figures.

1953 – 55 “1½ Litre (New Look) RME Saloon” (Latterly known as the “Spatted” RME).
Chassis numbers: RME 21855 – RME 23950

In an attempt to improve sales of the 1½ Litre Saloon a styling update had been ongoing since early 1952, the result of which was first seen by the public at the October 1953 Earls Court Motor Show.

The front and rear wings, and the running boards were the main changes, whilst subtle alterations were made elsewhere. The restyled front “helmet” wings now included integral headlamp pods, swept-in sidelights and built-in Lucas fog-lights and the front number-plate valance was amended to suit as were the outer ends of the front bumper blades. The doors were altered at their lower edge so that they closed snugly into a rebate on an outer metal-clad panel that sat above an outward curving sill that was adorned with a chromed strip. The rear chromed waist strip was elongated to blend into the rear wings which were changed to include a removable panel, known as a “Spat” and the wing top edge was dressed with a longitudinal crease similar to the front one. The fuel filler caps were now polished stainless steel. The chromed windscreen frames were narrower in section and slightly reshaped and the black leather-cloth roof covering had a chromed-brass perimeter gutter finisher, with rubber insert. The bulkhead scuttle-vents were altered to a vertical orientation and the body raised slightly on the chassis mountings. All other features remained the same as the earlier RME, i.e. all hydraulic brakes and hypoid axle.

This “New look” RME was well received and sales on the home market improved and whilst LHD version were available, sales of these and others to export markets were very low. The price of £850 (+ purchase tax = £1205) continued until its withdrawal on Jan 29th 1955, after 2096 cars had been made.
There were other small styling changes due to lighting regulation upgrades. At first rear reflectors became mandatory and then the required surface area of rear tail lights was increased and so the “D” lights on the spare-wheel panel were replaced by brake/tail/reflector lights affixed on purpose made plinths on each rear wing. This necessitated the rear number plate illumination/reversing light being fitted centrally below the number plate. Chromed stone-guard panels were also fitted to the leading face of the rear wings and wind deflectors were made available for fitting to the front doors.

The range of paint colours was expanded to include Black, Dark Green, Maroon, Ivory, Glen Green, Grey and Peacock Blue (M). Two-tone options were also available and in later years this “split” has become very popular.

The “Spatted RME” although thought to be a stop-gap at the time proved to be a styling icon which extended the “Magnificent Motoring” that Riley provided.


1952 – 1953

Superb lines and power to spare make this 2½ litre RMF “Sports” Saloon a pleasure to drive and a joy to behold, with a pedigree as “Old as the Industry”.

Chassis numbers: RMF 62S 9911 – RMF 10960

The 2½ Litre RMF Saloon, introduced in mid July 1952, was the final upgrading of the coachbuilt “Big Four” models produced at Abingdon. The designation “RMF” had been allotted by Nuffield/BMC for the revised braking and final drive system fitted to the heavy, and by this time, outdated chassis. The original Riley type of torque-tube axle was replaced by a Nuffield hypoid-bevel design that continued to provide a 4.11:1 ratio, together with an open prop-shaft and a rigid fixing of the forward end of the heavier leaf-springs. The Girling braking system was changed to an all-hydraulic one, still relying on 11” diameter drums, and the wheel hub studs were changed to UNF threads from BSF.

The 100 BHP RMB2 engine was to receive a further upgrade around January 1953 with the fitting of diagonal split con-rods with renewable shell bearings from engine number RMB2/945 and then almost at the end of production a new distributor with vacuum operated advance control was employed. Whilst the power from this engine was more than adequate, it was now becoming out-dated, compared to the opposition (Jaguar for example), whose engines were of the more recently designed “square” straight-six type and capable of achieving higher revs and more power output.

The bodies first fitted were of the small back window type, carried-over from the earlier RMB, but then from RMF 62S 10107 the revised big back window body and upgraded internal trim with flat-top seating was fitted. Paint finishes included Black, Autumn Red, Woodland Green, Silver Streak Grey (M), Grey and some in “special” requirements.
With a hefty increase in purchase taxation the “works” price of £1055 +purchase tax rose to a showroom price of £1642 and with further reductions in export sales the writing was on the wall, and so around late August 1953 the last of the coach-built Riley 2½ Litre Saloons came off the Abingdon production lines after a total of 1049 had been built.

An illustrious end to a fine car.

RMH – Pathfinder

1953 – 1957

The RMH model (known as the Pathfinder) was the successor to the RMF retaining the Riley Big Four 2½ litre engine but with a new body, designed by Gerald Palmer.

Chassis numbers: 501 – 5652

The Pathfinder was the successor to the RMF 2½ litre car and was designed, under Nuffield auspices, by Gerald Palmer as an enlargement of his Wolseley 4/44 and MG Magnette of 1949 to give the Riley series a modern ‘Fifties’ look. It was a 6-seater (with bench front seat) and had a right-hand gear change. It retained the RM series torsion bar and wishbone independent front suspension as well as the famous ‘Big Four’ engine, uprated first to 102bhp, then to 112bhp, with much improved oil circulation and cooling. It had a perimeter chassis, all-steel body and coil sprung ‘live’ rear axle, restrained by radius arms and panhard rod.

It was a genuine 100mph car and the final evolution of the Riley ‘Big Four’ concept from 1937. The most remarkable aspect of the car was its soft ‘ride’ which proved excellent at coping with uneven road surfaces. Early problems with the panhard rod mounting, which could break on hard cornering, were traced to slapdash chassis assembly resulting in misalignment.

The biggest mistake was to adopt the untried Girling ‘Autostatic Braking System’ which used a Clayton-Dewandre servo to boost hydraulic pressure. This system was to cause problems throughout the production life of the car (as it also did for Jaguar), though the remedy was simple: do away with the servo!
All the Riley ‘Big Four’ cars 1937-57 suffered clutch judder to some extent and the Pathfinder was no exception.

Rushed prematurely into production late in 1953, against expert advice, there were initial problems when the cars went on sale, as indicated above, but these were reliably sorted by mid-1954. Many owners thereafter got a fast, comfortable and reliable car that served them well for 10 to 12 years. Today a handful of owners still run them every day, with over 500,000 miles on their original engines. There were some important changes in the 1956 model (October 1955) which had a hydraulically operated clutch and the option of overdrive, a facility that is more use today than it was before motorways were built.

Despite all of the internal confusion and warfare between BMC and Nuffield, the Pathfinder was properly sorted by mid-1954 into a thoroughly reliable car. In fact, many owners attested that it was near-perfect. This was the version shown as the “1955 model” at the October 1954 Motor Show. It cost £1,240 including purchase tax.

The “perfect” 1954/55 Pathfinder did not need any options or refinements like overdrive but got them anyway, along with the C-Series gearbox which also allowed hydraulic clutch operation.

The 1956 model, although a somewhat different car from the “perfect” 1955 version, was an equally good car.
BMC discontinued the 1956 model at the very time it was getting a glowing press review – Autocar Road Test 1606, August 19th 1956.

Riley cars only had a specialised, limited appeal in the marketplace. Sales of the Pathfinder were similar in scope to those of the earlier RMB and RMF models, reflecting that ‘niche market’. The initial cost (including purchase tax) of the 1953-4 model was £1,382 but had reduced to £1,240 for the definitive 1955 model. Throughout 1956 and just prior to the 1957 Motor Show, the Pathfinder was the only Riley car available. Total production was 5152 cars.

The Riley team at Abingdon designed and built an experimental improved Pathfinder (code RMJ) in 1954-5, with disc brakes and which used Gerald Palmer’s overhead cam version of the BMC ‘C’ series engine. This could have been quite some car, but BMC management rejected it in favour of conformity and the final 100 Pathfinders (the 1957 model) went out on the Wolseley 6/90 chassis which had reverted to a rigid rear axle and leaf springs.


Bare Chassis Period Specials 

1945 onwards

Soon after the start of production and due to the pressures to make cars for export, a scheme was formulated to initially offer 1½ Litre cars in “CKD” (Completely Knocked Down) form.  2½ litre versions followed soon after. Whilst it was also offered to Australia, it was only the Republic of Ireland that was to take advantage. Nuffield Exports Ltd. had been created to oversee the export drive but as LHD models would not be available until 1948, overseas sales numbers were very poor. It was G.A.Brittain Ltd. of Dublin that took on the task, and CKD’s were dispatched in batches of four, all palleted, boxed or crated together and shipped out of Gloucester docks.

From mid 1946 production was on just the 1½ Litre chassis, 143 being built before the Riley move to Abingdon. 2½ Litre versions were started in late 1947 with 45 being made over the same period. Take up was slow over the remainder of RM production with totals of 212 1½s and 100 2½s being the final output, including 23 ‘spatted’ models.

RM Specials (Bare chassis)

The Riley factory also offered ‘Bare Chassis’ for independent coachbuilders to fashion their own creations.  Most of these were in the late 1946 to 1949 period, the most prolific style being that of “Estate cars”, usually “Woodies”, of which there were numerous coachbuilders who were taking advantage of the fact that these types of vehicle were initially exempt from Purchase Tax and also were allotted a greater ration of fuel.  Firms known to produce these include J Urquart and Son Ltd., Bonallack, Village Garage in Netherhampton, Vincents of Yeovil, Robert B Massey & Co Ltd, Mapco (Builders) Ltd, Swain Group and Frank Grounds (Coachbuilders) Ltd.

It now appears that only around 106 bare chassis left the factory and that Coupés, Dropheads and Tourers were the most common of styles built by many coachbuilders, including:- Bonallack, Epps Bros, Reinboldt & Christe AG, Trent Coachworks, Victoria Carriage Company, Verheul, Walter Kong, Crosbie & Cowley.

There were a few commercials built in the form of ice-cream vans, pick-ups, etc, and the likes of Tickford converted Saloons to include roll-tops and sliding roofs.

Riley Prototypes


Riley RMD Prototypes 1946 – 1949  by Jim Fletcher


No 2½ litre prototypes have survived but we can share period photographs of them.  As far as we are aware only three 1 ½ litre prototypes are remaining (December 2021).                                                                                    

Drophead Prototypes had been developed in Coventry in both 1½  and 2½ litre form, but only the larger engine car would go into production. 

After the final prototype had been displayed at the 1948 Motor Show, Dropheads went into production soon after the move to Abingdon in the Autumn of 1949.

The first chassis is recorded as 59D 5006.

Model Information

The four/five seat Drophead Coupe has the same accommodation as the RM saloons. The hood folds away behind the rear seat back into a box or canvas bag protruding into the boot space. External Landau irons do not encroach on the passenger compartment. Small winding windows facilitate the view for rear seat passengers unlike other claustrophobic convertibles. The hood is fixed to a narrow rail over the split front windscreens so that when folded away leaves an exceptionally clean side elevation. Although later changed, this detail still featured in some subsequent sales literature. Otherwise, the 1949-1951 production run of some 500 2½  litre cars closely followed that of the prototypes.

Two 1½ litres and one 2½ litre models appeared in the Cavalcade of Motoring in Hyde Park in 1946 and a total of seven were built in all. One, GRW 114, appeared in the film ‘The Callandar’ in 1948.

A photograph was widely used of a 2½ litre model, registration number NFC 400. A 1½ litre car remained on display on the West End showroom of J. James Ltd., the London Distributor, until 1951. Its first owner said that as it had never appeared in a price list he paid a small premium over the price of a saloon for his ‘new’ car LYX 92.

Riley RM Engines 1945 – 1957


The engines powering these magnificent cars had a long and successful history prior to being further developed for the post-war RM Series

This section written by Gwyn Morris


Riley Engine Production Chart

First of all we have the Riley Engine Production Chart, compiled by Gwyn Morris, showing developments from the late 1930’s to the 1950’s; we then take each engine in turn from 1945 through to the end of production in February 1957.


Riley 1½ Litre (Model type “A”) – latterly known as the “RMA” engine.

This lively 1½ Litre, 4 cylinder was the successful development of Rileys highly regarded twin-cam, hemi-head, long–stroke engine and provided the post–war RMA and RME models with adequate power and excellent performance for quite a heavy car.

Total number produced = 14150

Detailed Information
The basic design of the engine stems from the Percy Riley designed “9” engine of 1926, it being of overhead valve and underhead twin-cam design with short push-rods that operated valves opposed at 90° in a hemispherical combustion chambered head. This very successful design had been expanded to larger 6 cylinder engines and, in 1934, to a Hugh Rose designed 4 cylinder “1½ Litre” development of the smaller engine, latterly known as the 12/4 engine. In late 1938, further improvements were made to this 12/4 by Harry Rush’s team, which resulted in the 29S “12 h.p.” derivative, which paved the way for the post-war “1½ Litre” (model type “A”) to be introduced.

The main improvement to this post-war engine being the introduction of chain-driven twin camshafts. The design included a “Hot-spotted” cross-crankcase system for heating the inlet manifold and with a single SU carburettor and a compression ratio of 6.8 : 1 , the engine produced 54 b.h.p. at 4,500 r.p.m. Fuel consumption with the engine in standard form, can give between 26 and 34 m.p.g.

The con-rods big end bearings and the crankshaft main bearings were white-metal lined and with the option of a twin-carb set-up and high compression pistons the unit was capable of 60+ b.h.p. and giving the Saloon cars a top speed of up to 80 m.p.h.

A total of 13950 units were produced, plus spares and development engines, with only minor improvements to the rocker gear/push-rods and camshafts during 1952.

A truly remarkable mid-size engine that gives “Spritely” performance, and compared more than favourably with other 1½ Litre engines of the day.

Dates Produced: September 1945 to January 1955
Bore, Stroke, Capacity, Number of Cylinders:  69 mm bore; 100 mm stroke ; 1496 cc ; 4 x cylinder
UK RAC Rating: 12 hp
Models used on: Riley 1½ Litre Saloon – (Retrospectively designated the “RMA” Saloon) 1945 to July 1952; Riley RME Saloon – July 1952 to October 1953; Riley RME “Re-styled” Saloon (“Spatted”) – October 1953 to January 1955 (Latterly known as the “RME2”.


Riley 2½ Litre (Model type “B”) – latterly known as the “RMB” engine.

This long-stroke “Big Four” was a carry-over from the pre-war “16hp” engine, now with a water heated twin-carb’ inlet manifold and rated at 90 b.h.p. @ 4000 r.p.m. The AC mechanical fuel pump was dropped at the beginning of 1947 when an SU electric pump was fitted. In May 1948, the cylinder head was up-rated to 100 b.h.p @ 4500 r.p.m., by the fitting of larger inlet valves, and with only minor alterations to the crankcase casting, this version continued through to February 1952, when it was redesigned as the “RMB2” version.

Total number produced = 8233

Detailed Information
From the inception of the basic design of the 16/4 engine in 1937, much rapid development had been carried out prior to Rileys “troubles” and the eventual control of the Receiver. The details of the design that were to unfold, basically reverted back to the “cross-flow” head as per Percy Riley’s original design and so the 1939 engine was virtually the same as would follow for this post-war 2½ Litre type “B” engine.

A fairly straight forward cast-iron crankcase design with the three-bearing crank secured by bolt-on caps, and the cylinders were spaced apart to allow water cooling evenly. Chain driven twin camshafts positioned high in the block allowed short push-rods to operate the rocker gear of the hemispherical combustion chambered cylinder head. The inlet and exhaust valves were of the same size and opposed at 90° to each other. The oil pump, distributor, (and for the first 170 or so), the AC fuel pump, were driven off the three bearing inlet cam. The belt driven water pump, complete with thermostat housing, was mounted at the front of the head and circulated the coolant through a left-side water manifold above the exhaust manifold, and a smaller auxiliary belt drove a cooling fan.

On the left side, twin SU carburettors were mounted on an aluminium inlet manifold, as well as an external vertically mounted Tecalemit oil filter, and a high output dynamo. With the polished aluminium twin rocker covers, as well as the carb’ intake manifold and carb’ dashpot, the engine was neatly presented.

This long stroke, high torque, low revving engine was powerful and surprisingly smooth for a “Big Four” and would provide “Magnificent Motoring” through to 1957, albeit with further development along the way, the most notable being the re-worked cylinder head.

In its initial 90 b.h.p. form 1200 units were produced, of which 215 were fitted into the “Warwick” Healeys, and then after being up-rated to 100 b.h.p. a further 7033 were made of which 535 went to power Healeys.

Dates Produced: July 1946 to January 1952
Bore, Stroke, Capacity, Number of Cylinders:  80.5 mm bore; 120 mm stroke; 2443 cc ; 4 x cylinders.
UK RAC Rating: 16 hp
Models used on: 2½ Litre Saloon (Latterly known as the RMB); Roadster (RMC) & Drophead Coupé (RMD).

Also used by Donald Healey in the “Warwick” Healey range of models from 1946 to 1952.


Riley 2½ Litre RMB2
Basically the same as the earlier RMB, but with alterations to the water-pump type, front mounting cross member, camshafts and distributor rotation. Part way through the production period, there were minor modification to the crankshaft and the con-rod design was upgraded to allow them to be removed, complete with their pistons, from above, up through the cylinder bores and included thin-wall shell-bearings.

Total number produced = 1680

Detailed Information
This “Big-four” engine, the basis of which had been designed in 1936/7, had been developed both pre and post-war to be very well thought of as a powerful, high-torque engine giving relaxed and high speed cruising. With improvements to the valve-gear and camshafts the engine was quieter, and the revised water-pump type and fixing position, allowed the use of a single fan belt. The engine whilst having the same bore and stroke as the earlier RMB version, and still giving 100 b.h.p. at 4500 r.p.m., was now a smoother unit that could achieve speeds in the region of 100 m.p.h. Fuel consumption varied between 17 – 24 m.p.g. depending on type of use and with the eventual fitting of diagonal-split con-rods, major engine servicing was made more convenient. Further refinements were made later, including vacuum automatic advance distributors.

Whilst the earlier engines still had white metalled con-rod big ends, the last 736 were fitted with diagonal-split con-rods lined with shell bearings.

In its day this engine had been a “high performer”, but with the lifting of the RAC Horse-power formulae in 1946, other manufacturers, such as Jaguar were able to design “Square” engines that would rev higher, and were lighter and cheaper to produce and so the Riley “RMB2” engine was destined for retirement, although one more upgrade was to be developed that would follow in the Riley “Pathfinder”.

Dates Produced: February 1952 to September 1953
Bore, Stroke, Capacity, Number of Cylinders: 80.5 mm bore; 120 mm stroke; 2443 cc; 4 x cylinder.
UK RAC Rating: 16 hp
Models used on: Riley 2½ Litre RMB Saloon (Feb to July ’52); RMF Saloon (July ‘52 to Sept ’53).


Riley 2½ Litre – Pathfinder (Model type ‘D’)

This was the final development of the pre-war, Riley designed “Big Four” . It would be the final link to the old Riley company, and would provide the power for the sleek new “Pathfinder” model designed by Gerald Palmer from the Nuffield Design Office in Cowley, during 1950. With minor upgrades to the ancillary components, mounting points and internal parts, it was eventually refined to produce 110 b.h.p. at 4500 r.p.m.

Even though it was powerful, as a heavy, costly, long-stroke engine it was “doomed” to be dropped after the merger with Austin and the formation of BMC.

Total number produced  = 5254

Detailed Information
The basic design of the 2½ Litre RMB engine had proved itself to be dependable and worthy of further development and so it was to receive various improvements to further increase power output and economy of manufacture.

Some of the components and design details that were altered were, the water pump, oil filter canister alignment, rocker covers were now secured with perimeter studs, the dynamo was positioned on the left side, and together with a redesigned cylinder head, the exhaust manifold was altered. The engine was mounted to the chassis rails via side mounted brackets, although these were later to revert back to mountings attached to the timing case casting.

With the crankshaft main bearings now fitted with shell bearings and a slight change to the pistons, camshafts and induction set-up, it initially produced 102-4 b.h.p.at 4400 r.p.m. with 6.97:1 compression ratio, and then with the fitting of high compression pistons and a thin steel head gasket, the compression ratio was raised to 7.25:1 and the b.h.p to 110 at 4500 r.p.m. This configuration meant that the “Pathfinder” was now truly a 100+ m.p.h. “Sports Saloon”.

All in all this well proven pre-war design was able to “hold its own” well into the late ‘50’s against most other 2½ Litre engine Saloons, perhaps with the exception of the “square” Jaguar 2.4 with a lighter body.

Dates Produced: May 1953 to February 1957
Bore, Stroke, Capacity, Number of Cylinders:  80.5 mm bore; 120 mm stroke; 2443 cc capacity; 4 x cylinders.
UK RAC Rating: 16 hp
Models used on: Riley 2½ Litre “Pathfinder” Saloon – (RMH).

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