Engines : C-Series

The C-Series engine was the shortest lived out of the triumvirate of BMC engines, and has since gained infamy for being the motive power behind of the MGC and Austin 3-Litre.

Sadly, it’s been underrated ever since – unless you’re a Healey owner.

Words: Tony Cooke

Unloved, but not unworthy

THE C-Series engine was the third of the engine projects generated by the BMC merger. It had the shortest production lifespan of the three and perhaps, because there are few out there with first hand experience of it in its various applications, it receives little press and, as a consequence is seen as somehow ‘lesser’. The facts indicate that this was a very worthy design, in several ways superior to that of its smaller relatives. The features and history of this engine are worth further study.

The timeline and history of the engine is fascinating and mirrors that of its parent organisation, in its successes and failure. It is hard to imagine that in the 1950s the UK was the biggest exporter of cars in the world. The merger of Nuffield and Austin created the UK’s leading industrial company, one with World renown and footprint. The need for economies of scale were not lost on the organisation. While there were still some awful products to be designed, there were, during the next few years, many winners produced. Some cars have quietly disappeared off the stage and yet they sold well, were contemporarily competitive, sales leaders in the UK market and did all that product placement required of them, competently. The C-Series engine is one of these products. The early 1950s was a time of significant profitability for BMC. A lot of good decisions were made.

To consider the design and assess its merits the context needs to be described. Rationalisation was not a process that started with the merger of BMC, when Lord Nuffield signed the deal without consulting his board. Pre-war the Nuffield organisation had produced a total of 38 different models. By 1946 this was down to just 10. The number of different engines went also fell in the same period from 21 to 5. In 1947 percentage of car production within the UK was split: Austin 20.9, Nuffield 19.2, Ford 15.4, Standard 13.2, Vauxhall 11.2, Rootes 10.9, Rover 2.7, Singer 2.1 and Jaguar 1.6.

Throughout the war there were many examples of poor management and control of expensive production facilities. The Castle Bromwich aircraft production facility had to be rescued after a very inauspicious start. The later history of success totally belies early production traumas. Throughout the post war period the Government was rightly urging rationalisation and scale of production on the motor industry. Long gone was the argument that Government should, at all times, keep its nose out of commercial industrial affairs. It was widely recognised that a return to post war practises would result in economic collapse.

The original A-Series appeared in 1952 in 803cc form. The B-Series engine appeared first in 1952 in 1200cc form quickly evolving into 1500cc. Both of these engines came from the Austin design team led by Bill Appleby, Eric Bareham and Jimmy Rix.

Nuffield had an engine plant in Coventry called ‘Morris Motors’. During the First World War, Hotchkiss had moved from France to England to continue war production and had set up in Gosford Street Coventry. In 1923 Morris bought up the Hotchkiss company renaming it Morris Engines Branch. 30 years later Morris engines had a successful design and development operation. It had outgrown the original Gosford Street site and in the mid-’30s a huge investment was made in new facilities at Courthouse Green. This was a vertically integrated (foundry to finished product), engine production unit, providing the bulk of the IC engine needs of the Nuffield group. At the helm was widely respected industrialist Frank Woollard. (Would that be another bright ‘Morris Light’ that needed to be extinguished by the more enlightened souls of Longbridge?)

It is not been possible to determine the exact timeline of the C-Series design in relation to the merger. However it is known that the A- and B-Series engines were significant projects prior to the merger. The B-Series engine being a redesign of a 1947 1200cc, which was one of a pair of units produced by the ADO unit and was apparently cribbed from a Chevrolet six-cylinder OHV unit that Vauxhall was building. The other of the pair was a 2199cc four, finding use in a variety of Austin vehicles. Production of this engine would, bizarrely continue for many years after the introduction of the corporate large engine – the C-Series.

It is probable that there had also been prior development of the C-Series engine. It may be that rather than engines designed on a clean sheet of paper to a grand, post-merger, strategy, there was rather a pragmatic decision: bring to the table everything you are working on at the current time.

Right – Austin team – you follow through these two engines to volume production; Morris Motors, you do the same with this one and we will use these are the ‘small’ ‘medium’ and ‘large’ engines to power our corporate range. No others. If we can common up on any trivial components like tappet covers, cam and crankshaft timing gears and the like, we will do so.

Wolseley 6/8o was an early adopter of the Nuffield C-Series.
Wolseley 6/90 was an early adopter of the Nuffield C-Series.

So to find out why the C-Series is like it is we must look at what was available to Nuffield, in the large engine category, prior to this and to a lesser extent, similarly with Austin. The Nuffield organisation of 1951 comprised Morris, MG, Riley and Wolseley. In terms of engines, product was innovative if not successful. The principal engine was the 2215cc six-cylinder used in the Morris Six and Wolseley 6/80. Production of these started in 1948 and finished in 1953/4. Quoted figures for outputs from this engine are 70bhp for the Morris and 72bhp for the Wolseley. Both featured carburetion via single SU.

These engines were produced together with a truncated four-cylinder version of 1476cc using identical bore and stroke. Outstanding for the time, both these engines featured a single overhead camshaft. Over five/six years production of the Wolseley 6/80 was around 25,000 and about half that number were fitted to the Morris Six. So production is at around 6000-7000 units per annum.

Over at Riley, purchased by Nuffield in 1938, the ‘Big Four’ 2443cc engine had come out and was used in the RMB – RMF series. This was a twin SU, twin overhead cam engine that initially produced 90bhp in original form, with a nominal 100bhp being quoted for later variants. In a production run from 1946 to 1954, the most populous model was the RMB at 6900 units with quantities for other derivatives at 500, and that for the final incarnation the RMF, being only 1000. This gives a somewhat modest production rate of around 1200 per year at best. It should be remembered that the 1500cc version of the RM sold in greater quantities.

So if we follow combustion engine design history, for volume production engines, we can place the C-Series engine. In terms of valve gear and general arrangement there is sleeve valve/poppet valve mix up until the 1920s, when poppet establishes ultimate precedence. Then there is the pre-war mix of and side valve and overhead valve layouts. Jaguar used Standard’s side valve engine on its performance saloon. Even after the war many successful and popular cars continued with side valve engines well into the mid-’50s. Ford’s 1959 Anglia 100E probably being the last volume-selling side valve in the UK. However by the ’50s pushrod operated overhead valve, was the dominant design. It was not until the 1970s that volume production of OHC engines took hold.

At first with only two valves per cylinder. Crossflow porting was then facilitated. It took until the 1990s for twin-overhead cam, four valves per cylinder layout to become a common feature on many popular production cars. Of course against this general trend there were many exceptions. Some outstanding in strategy and execution (e.g. the Jaguar XK). Others outstanding in concept but faulted in execution (e.g. the Dolomite Sprint). At the other end of the spectrum were retrograde steps like the 4-litre B-Series Rolls Royce engine of 1964 with side cam, side exhaust and overhead inlet by pushrod. Regressive in concept and faulted in execution.

The conundrum: why would a volume manufacturer with a technically advance large engine featuring a SOHC, with a track record of having sold well and all the experience of producing a large twin overhead cam engine, then opt for a pushrod operation for their new large six? Rapidly failing from our memories are the disasters of unreliability of the Dolomite Sprint and Stag engines and the serious and long lasting impact this had on sales, not just of the vehicles concerned, but contaminating the whole brand, for a long time. A fastidious owner of a much cherished classic offers a inspection and maintenance regimen much removed from that of the careworn owner of a three-year old car. The single OHC six- and four-cylinder engines of the Morris/Wolseley cars were the Dolomite Sprint engines of their time. They were more powerful than their contemporaries. They had a design specification well ahead of their contemporaries. However too many customers were left saying ‘never again’.

Riley 2.5.
Riley 2.5: Customers preferred the cheaper 1.5.

Burning of valves when continuously loaded for any period of time, was the most common fault. Was the Riley 2.5 a commercial success? Well, the facts relating to sales tell a very different story – apparently the customer preferred the lower spec, lower powered 1.5-litre. A specialised engine of complex construction requiring specific production facilities and being produced at a rate of 1200 per year? Looking back with the benefit of hindsight, the figures certainly do not look good. At this point in history it is hard to know whether the 2.5 twin cam was overpriced for its market slot or whether there genuinely was not the customer base to support more sales. The dated appearance of the vehicle, while quaint now, was not contemporary and must have negated sales.

In determining the design brief for the engine we need to recall how Austin/Morris/BMC products were viewed relative to their major competition. They were not products purchased by those who sought outright road performance. The represented a sound investment. Value for money, economy of operation and improved reliability over their Ford and Vauxhall rivals. They were not ‘flash’. As the decade wore on they would position themselves as having greater economy of fuel consumption than the Ford counterpart, even if the Ford product offered a more contemporary appearing product for the price.

So the design brief must have been – produce something with large capacity, relatively economic to produce. It should be highly reliable in operation and giving good economy in terms of fuel consumption versus power output. Good ultimate power output will be achieved by engine swept volume, rather than complexity in valve arrangements. It must also be easy to maintain. It must give greater refinement that that available from the Austin 2199cc four-cylinder engine.

Perhaps not written anywhere was ‘get it out quickly, we need something to replace the SOHC six that is wrecking our reputation’. Which probably supports the idea that the engine was already partially designed before the BMC merger.

Against the designated capacities of the A- and B-Series engines, something of the order of 2300cc would have seemed logical.

The volume of sales of the cars to which this engine was to be fitted would be low, this was after all post war ration-card Britain. Therefore total profits available to the corporation would be low. However damage inflicted to sales of all cars, by a poor reliability record of a flagship model could be totally out of proportion. The risk reward aspect of producing a small volume flagship car were skewed against innovation. To a significant extent that was what had happened with the 6/80. It was very important that the next engine ‘worked’.

Against that backdrop and the fact that the series of engines the C-Series was replacing, SOHC 8/80 Austin 2199cc four-cylinder and Riley TOHC 2.5 litre, had a production life of less than 10 years, it could reliably be thought, that when designing the engine, the prospects were that by the start of the next decade, the design team would be looking at replacing the C-Series and could then consider, once again, a more complex valve arrangements and porting. Neil Cairns suggests that the intent was that all three series of engines would have a five-year production life. Given the position of the new BMC as a major global car producer with a World based reputation to uphold, such a precept seems entirely feasible.

That this nearly came to pass is another feature of our story we will encounter.

On a sheet of paper the A-, B- And C-Series are akin. Long stroke, pushrod operated OHV, cast iron block and heads. three mains for the fours and four for the six

However the detail tells a different story: both the A- and B-Series engines feature the cam on the right hand side. Chain driven in all cases but Duplex in the case of the C-Series and with a proper hydraulic Reynolds slipper/tensioner dowelled to the block rather than a piece of steel sprung against the timing cover. However the A and B series engines also feature all their porting on the right.

The C-Series engine has all the porting on the left, but the cam on the right. This has two significant advantages. Porting does not have to negotiate tubes around pushrods, thus there is significantly larger areas of material through which ports can be run. Ports can be larger and have a cleaner flow in. The distributor can be easily run from the camshaft and spark plugs easily put in the non-port side of the head. At this next step of layout the C-Series engine had thus gained a significant advantage over the A and B. the A and B series both featured partial flow oil filtration until later modification required that it be upgraded. Right from the start the C-Series engine had a full flow oil filter.

Did animosity linger between the design factions of Austin and Morris. Certainly, even in early 1970s there was great resentment at the Morris Motors plant at this time, in that they were gradually being run down and had been starved of investment for over 10 years. The focus of this resentment was the Austin people at Longbridge. What would the attitude have been soon after the merger when each team cast their eyes over the offerings from their rival? ‘Austin boys – you have the two main volume engines – but we can design the better engine, just you see’ ‘Morris – you might be ‘smart’ with a better engine layout but we run the show – just you wait and see.’ Imaginary, but given the multitude of apocryphal tales that emanate and which seem to have facts which tie into tale, it is not inconceivable.

And so to the engine. Was the comparatively large 2639cc chosen to given volume leeway to offset a loss in specific (bhp/cc) performance over the 2.2-litre OHC engine that had preceded? Certainly it must have been a factor. Probably a greater driver was the need to move the models it powered, further upmarket and leave room for the multitude of vehicles that were going to fill the small/medium sectors. Despite its reliability record, the 6/80 had cemented the idea in the mind of the British public that it was the cops car – good performance and roomy. The new models needed to build upon that and the BMC group could move its flagships further upmarket.

Was further upsizing of the engine anticipated? No facts relating to any thoughts in this regard are known. The stroke of 3.5in (89mm) was chosen in common with that of the original B series engine. But whereas that featured a 2.58in bore, the first evolution of the C-Series had a bore at 3.12in (79.5mm) bringing its dimensions far closer to square than either of its two relatives – 0.89, v. 0.74 – B, 7 0.76 – A.[original A-Series: 58mm bore 76.2mm stroke]. On later enlargement it would become even closer to square as the bore size increased further.

There were other differences. The conrods were diagonally split to facilitate the rods being able to pass up the bores and the gudgeon pins were clamped by bolt and lock washer in the end of the conrod.

The water pump was belt driven and bolted directly onto the front of the block. Flow to the back of the cylinder head was achieved via varying size holes in the entirely copper clad head gasket. Bypass water flow was via a direct path from under the thermostat into the water pump. There was a port towards the rear of the cylinder head to provide supply for the heater and then return into the bottom hose. Heater controls on the Smiths heaters used throughout the life of the car allowed for complete closure of water supply only at ‘cold’ and full flow at all other settings.

However since at ‘cold’ no water would flow along this path it was imperative that flow under the bulb of the thermostat was good. This is the case and the engine was excellent in terms of suffering no hots spots despite Siamesing of bores within the casting. The large dimension water gallery passing along the length of the block from behind the pump undoubtedly provided good circulation. With a large hot climate, overseas market, the cars were equipped with substantial radiators that gave good allowance for degradation in performance due to age. The engine was not prone to heating problems.

In terms of benefiting from the advantages proffered by uncluttered porting, the initial design results seem somewhat ambiguous.

Individual ports were provided for the exhaust from each cylinder. These exited into a pair of manifolds, each mating to three ports. (Are Isis and 6/90 the same?) All dimensions were generous. Perhaps one of the most successful features of the design is the exhaust arrangements. The later 12-port head takes the identical original porting sizes and arrangements for the exhaust and just casts them into the different head. Identical exhaust manifolds are used.

The original design was for twin 1½in SUs. However BMC wanted to achieve product diversity and so there was a single SU and a single Zenith downdraft version as well. In all cases the carburettors bolted straight onto the head. Cast into the head was a gallery inlet manifold. This was actually generous in its allowance for each cylinder with an individual tract for each from the gallery. However the gallery itself was somewhat narrow and a row of cylinder head studs passed through it centrally. At low engine speeds these would have no effect but at ultimate performance they would offer some restriction. It is to be remembered that this engine was to be produced at a time when carburettor icing was a common cause of breakdown. The gallery head prevented any such problem and the selection of the appropriate number of insulating blocks between the head and carburettors, at the design stage achieved the necessary supply of heat/insulation to the carburettors. A heat shield was fitted over the exhaust manifolds.

The crankcase was sturdily ribbed. The dimensions of the main bearings and big ends were generous by comparison to its competitors. Mains were 2-3/8in diam and 1.5in long. Crank pins were 2in diameter. Crankshaft end float was taken by thrust washers fitted each side of journal number two.

The camshaft was driven by duplex chain. Two separate skew gears were provided, one each for the oil pump and distributor. This reduced the loading on the distributor drive gear by a huge margin and would allow the accuracy of the distributor to be maintained over extended mileages. Again an advantage over the A and B series and other contemporary designs. A small jackshaft provided drive from the cam to the low mounted oil pump. Full volume oil filtration was provided with a pressure relief valve operating should the filter become clogged. The pump output was good and oil way drillings and galleries well positioned and generously sized such that blockage was never an issue.

The gallery relief dumped back to the sump and operated at 55lb/in2 Starting from cold causes the relief pressure to be reached and this condition is maintained for some time. The camshaft was carried in four thin wall bearings, line reamed after fitment. Replacement bearings were available. Tappets were of the cast type of hollow construction and porting for lubrication. The tappets ran in bores within the block. Solid pushrods provided lift to slim cast iron rockers. The rockers featured thin wall bearings that could be replaced if needed. Drillings within the rocker provided oil outlets onto the valves and back to the ball in the socket of the pushrod.

The combustion chamber was of the Weslake patent. However Weslake was to do additional work some years after the introduction of the engine around 1960 to further enhance the performance of the engine.

Initial applications were:

  • Austin A90 Single Zenith 2693cc 85bhp
  • Morris Isis Single SU 2693cc 85bhp
  • Wolseley 6/90 twin SUs 2693cc 95bhp
  • Austin 100/6 twin SUs 2693cc 102bhp

Engine production started in 1954 with most cars shown at the motor show and delivery to the dealers following shortly thereafter. The Austin models were a great success right from the start. With realistic aspirations for moving upmarket a Vanden Plas version was added to the range in 1957. Sales of the A95 and 105 were over 28,000 and 7000 units respectively.

The Morris Isis sold poorly with only 8500 of the series I car needing to be produced. The Series II faired even worse with a two-year production run of just 3600 cars. A twin-SU version of the engine was fitted to a rather stillborn revision of the Riley Pathfinder, called the Riley Two-point-Six. The Pathfinder already had a blackened reputation courtesy of a poor rear suspension layout that was only corrected after the damage had been done (the ‘Ditchfinder’) and for Riley aficionados, another modification to fit an engine that was a retrograde step on their top of the range model, this was perhaps a model placement and execution that was a sign of what BMC/BL were to become famous for. Just 2000 units were produced before it was killed off and with it departed Gerald Palmer, his career at BMC over.

However before we move away from the 2.6 we have an interesting aside. Gerald Palmer was very proud of having managed the twin cam MGA project. This was the famous twin cam version of the B series engine. Palmer claims that ‘he originated the policy and laid this out on my own drawing board at Cowley, it was detailed by Jimmy Thompson’s team at Courthouse Green in Coventry.’ Next claim was that he laid out a twin cam version of the C-Series engine with a definite plan to ‘out jaguar the Jaguar’. Palmer claims that a prototype engine was produced.

The intention was that this was going to power the big Wolseley and Riley cars. (The twin-cam was originally to power the ZA Magnette. Set in the time-line of the OHC Wolseley and twin cam Riley big four, it makes a valid product projection. It is no secret that Cowley recruited and orientated Palmer was an outcast in the Austin-biased BMC organisation, and was living on borrowed time. Was taking the twin cam layout to the Morris Engines design team one slap in the face for the Austin engine people? Was the idea of having a twin cam C-Series a further slap too far? Why were the ‘melting pistons’ problems not cured before production? However during 1955 Palmer was gone and with it any hope of grander things.

Austin Healey 100/6
Austin Healey 100/6 initially offered few advantages over the original 100.
Austin Healey 100/6 engine
Austin Healey 100/6 engine was a tight fit.

In the Healey, the C-Series engine performed adequately, but no performance advantage was gained over the 100/4 it replaced. For 1957 a 12-port head was introduced on the Healey, increasing power from 102 to 117bhp. The exhaust porting is identical to those within the gallery head, in which there is an individual run from each cylinder to an individual port in each of two separate exhaust manifolds. No change there.

But the inlet gallery is removed and the individual ports of each inlet valve were now run out into three sets of siamesed twin ports on the side of the head casting. Separate to the head was an inlet manifold which then provided two off 90-degree bends for the inlet tract as air entered via twin SUs into the manifold and then into the run to the valve. Was this very different to the gallery head? Well the advantages were that the gallery manifold had bolts passing through it and these were not present in the separate Healey manifold and the SUs were up to 1¾ in from 1½in earlier. The 100/6 now offered a significant product upgrade over preceding models.

For 1959 BMC went Farina with its large saloons. Along with the Healey all featured an increase in bore to 3.281in up from 3.125in, making for a volume of 2912cc. The Saloons fixed on 2×1½in SUs and the big Healey was at first on 2×1¾in carburettors. Now we start to gaze on murky waters. The A99, Wolseley 6/99 and Vanden Plas Princess range are credited with 108bhp. The Healey with 125bhp. They and the big Healey are selling well. However the saloons are road tested by Autocar and Motor and while one-way best speeds, dependent on transmission are above 100 mph, vitally that mean speed is below the magic barrier.

For 1961 new versions of the saloons and sports car come out. As for the smaller ‘Farina’ siblings, a plethora of small but effective modifications were carried out throughout the cars. The engines were also upgraded. Quoted outputs are 120bhp for the saloon and 132bhp for the sports car, which has now changed to 3×1½in SUs. An Automatic VDP saloon with air conditioning achieves 105mph mean and 106 one way with Autocar. A manual 6/110 achieves 101.8mph mean but at 5400rpm in top is running out and a rather too long overdrive of 27.7mph/1000rpm leaves the engine relaxed but well away from peak power at 4750 rpm. The Healey gives a top speed of 111mph with the Autocar but disappointing performance with the Motor in July 1961.

This is an article about the engine so we will not dwell too long on the history of the cars to which they were fitted at this moment. However, relevant to our tale are three subsequent events. The 1961 saloons were very quick for their day. Along with modifications to the inlet tract in the gallery head, were new twin exhaust systems and a move to the corporate exhaust valve timing of 51–21 as opposed to the earlier 40-10. There was no change to inlet timing.

Results in BMC power tests are: Saloon – Gross 126bhp, corrected 120.7 and installed 115.5bhp. However the three carburettors were short lived. Soon there was a new version of the MkII Healey with a change back to twin 1¾in SUs and more aggressive valve timing with 9.7 compression. Here the equivalent test data which I do have states 137bhp gross, 132bhp corrected and 128.8 installed. The torque of the saloon’s engine is greater all the way through to crossing at 3500rpm.

Less than one year after introduction of these 1961 changes In another BMC engine test result sheet, it’s stated across the top quite clearly ‘Confidential – not for publication’, and details the performance of the engine as it is detuned from that moment on. Installed power drops to 110bhp. For the remaining six years of production of these saloons they feature reduced engine performance, however no mention of this is made in publicity material which continues to quote the power output of the engine as 120bhp – that at the 1961 change.

At this time Autocar are able to test the new version of the Healey and report significant increases in top speed and acceleration figures. Speculation only, but had the boys at Morris Engines done too much? It might have been quite enjoyable to poke fun at their apparently anachronistic gallery head. ‘Donald Healey had to come along and design a 12-port head and only then was it any good !’ Now it appeared that the gallery head was not as bad as it was presumed to be. Suddenly the saloon was getting a bit too close to the sports car and that was not good. The new Mk II Healey was soon replaced by the MkIII with even bigger carburettors and a genuine 150bhp, (154 Gross, 149 corrected and 147 installed). We know rivalries were playing havoc throughout BMC. Didn’t Donald and Geoffrey Healey cry ‘foul’ against Sir William Lyons regarding developments of the replacement to the Healey 3000?

So we have the wholly Morris Engines responsibility, saloon engine being detuned. The Healey engine being further tuned twice more in very quick succession.

The third element of the story is the development in 1959/60 of the six-cylinder Blue Streak engine. A six-cylinder version of the B-Series. Was this project from the Austin Engine team the catalyst for the significant upgrade in performance of the C-Series saloon engine by Morris Engines? Was the improvement in performance of the C-Series at that time, one of the reasons the Blue Streak project was stillborn in the UK – no need now the C is upgraded? Speculation. We certainly know that Bill Appleby of the Austin engine design team made the subject of his invitation to give the Crompton –Lanchester lecture to the IME in 1960 as the BMC B Series Engine. What a coup if it evolved into a six and heralded the end of the Morris Motors C. We have no facts other than, only Australia went ahead with the Blue Streak. The Courthouse Green, Morris Motors factory now hosted the production of the A-Series for the mini.

The C-Series lived on. Still not out of the mix was the Austin 2.2-litre four-cylinder, 1948 sibling of the pre-B Series engine, still being produced and finding application in the FX4 and other commercial vehicles.

Then there is the involvement of Harry Weslake back at BMC again. He was working on a very specific C-Series engine project. Immediately prior to this he had been contracted to work on the 3-Litre overhead inlet, side exhaust valve engine at Rover to try and get it to keep pace with the offerings priced below it from the volume producers.

So at 1961-1962 what was the next stage? The C-Series had been in production for eight years. The model range it supported was successful in all aspects. Production of the saloons easily outstripped the rival offerings from Rootes Brothers and Rover at around 17,500 per year for 1960, 1961. Critically, unlike other products, the saloons were economically successful as well.

The big Healey added another 4500 units per year. A rational business model would have looked for replacements, looking to build on the gains of the achievements of rationalisation and concentration of effort. A replacement for the Big Healey, a revised big saloon to sit in a market segment slightly above the Zephyr/Zodiac range, which was selling at around 32,000 units per year. Ford would go onto produce a fully independently sprung Zephyr Zodiac as the next incarnation of their big salon in 1966.

In 1962 BMC was well placed to steal the march on them and get into the market place earlier. While both Rover and Triumph would release outstanding two-litre executive cars, the popularity of the offering from Ford and the fact that into the mid-’80s Datsun/Nissan would still be selling a direct descendant of the A50 built under licence, which had evolved, like the Austin products, into a large, highly conventional 2.8-litre saloon, was proof that the market existed.

The Datsun Cedric remained in production with a live rear axle and double wishbone front suspension, and an inline six-cylinder engine through to the end of the fifth-generation in 1984. Another glimpse into the history to indicate that in some aspects Datsun was still ‘following’ BMC is that for the 1965, second-generation of the car, Nissan also went to Pininfarina for the styling. Under-the-skin technology was still behind. While the big saloons from BMC had gone to disc brakes in 1959, it took until 1971 for the Cedric to convert. By October ’77 Datsun had produced one million Cedrics in 17 years. The success of the accompanying 240Z sports car is well known.

Austin 3-Litre was the C-Series engine's last hurrah
Austin 3-Litre was the C-Series engine’s last hurrah.

Therefore, in 1961/62 BMC was undoubtedly still very much in the game and at a critical point. It needed to design replacements for its big sports car and saloon. To power both of these vehicles a new ‘large’ engine would add to the product enhancement. We know that development of the new big saloon, which would eventually splutter, very late, into still-born life as the Austin 3-Litre, started around 1963. It would feature North-South engine and rear wheel drive. In terms of the engine development there are three separate events to describe.

The endless argument about the history of the British motor industry product lines is as to whether there actually was money available for investment in new models in sufficient quantities to produce viable new product or whether there was adequate money and it was squandered on the wrong project at the wrong time and let down with poor attention to detail. In the case of the C-Series engine the story is quite straightforward. In 1962 – sometime into the near future, the C-Series needed replacing and the decision to replace it was made.

First hand evidence is hard to come by and, given the eventual outcome, perhaps those who knew more than most, were reluctant to associate themselves with the debacle that followed and so kept quiet. One individual I know, who worked at Morris Engines for many years – 20 years plus, had views that the whole story was without glory at every level. Nobody shone and so nobody wanted to talk about it. No investment in production facilities was made in the period 1958 through to 1965.

The engine plant was carried along with the rally successes of the Big Healey, in the ’50s and early-’60s. The Wolseley 6/110 was the Police car and had a reputation as delivering performance and reliability as an economic and competent package. The Vanden Plas Princess 3-Litre had won the Mobil Economy drive with an incredible 34.4 mpg.

The product was good – why change a winning but conservative formula.

Suddenly there was a realisation. The Healey rally program had been cut, the car was no longer competitive. There was a big car replacement being designed and it was going to be highly innovative – yet another World beater from the Austin design team. What was needed was a new engine to power it.

The three events that interact on the redesign of this engine:

  • the in-house redesign of the whole engine
  • the potential redesign by Harry Weslake and associates
  • the diversion generated by the four-litre Rolls-Royce engine.

The least known of these three is the Harry Weslake redesign. We know that Harry had done contract work for BMC and in particular work on the A-, B- and C-Series heads. There is speculation that Harry was involved in the gallery head improvements, that became part of the 1961 changes. Some 25 years ago, I was in conversation with a close relation to him. That relation described a project Harry was commissioned to do by BMC. It was a major redesign of the C-Series engine.

The relative described still possessing in a garage or store, a prototype engine. Undoubtedly it was a C-Series engine because its bulk and difficulty to move it created significant problems in storage. He offered it to myself, but unfortunately events in my life prevented me taking him up on his most kind offer. Apparently the re-design involved the repositioning of the camshaft to higher up on the side of the block. This facilitated a different valve arrangement.

The project went nowhere. As to the motives for stopping it, one can only speculate. Was there some resentment that Weslake received royalties on every A-Series engine produced? Was there some form of jealousy that someone from outside had ‘breathed’ on the much maligned gallery head and it produced results so comparable to the much vaunted 12-port head? Did Weslake demand too high a price for his services? Was it management bungling? Facts show that It certainly would not be because there was something better on the table. All we can say is that an opportunity that opened for BMC to significantly redesign the head and porting of the C-Series engine in the early 1960s, via the services of Harry Weslake, was passed by. The window closed, regardless of the fact that we do not know whose hand was pushing the latch.

The second aspect to impact on the development of the C-Series is that of the Rolls-Royce engine. The history of the use of that engine is documented elsewhere. Relevant to our story is that ‘wine’ was again turned to ‘water’. This project highlighted the risk reward ratio for the flagship car in the range. Sales of the 4LR were disastrously below those of the Vanden Plas 3-Litre it replaced. One had an ever growing reputation. The subsequent model the opposite.

While much time and effort was wasted on developing a car that was a commercial disaster and so impacted on BMC’s reputation for reliability, focus was lost elsewhere.

And so to the first event on our list – the in house redesign of the BMC C-Series engine. According to a first hand witness, the plan that was drawn up was principally geared around a simple premise of how a new ‘Healey 3000’ replacement might be competitive on the rally scene once again. Key to this concept was that the engine needed to be lighter and capable of producing more power. The consensus view of the ‘team’ held that at around 175–190bhp (depending on who you believe) the current engine’s bottom end became the limiting design feature.

Four-main bearings were not enough for higher revs and more power. Also at 598lb with standard clutch, it was too heavy. Simple solution – add some more main bearings. And whilst the block and head patterns were being redesigned and re-made, take advantage of modern thin wall casting techniques to thin the crankcase and head in regions where strength was not needed, to produce a reduction in weight. After all the patterns were unchanged from 1952 when the engine was finished off in a rush to get it into the new models and ‘caution – it must be reliable and strong’ was the key driver.

High pressure die-cast aluminium castings were to be used to replace steel for all ancillaries. The target set for weight reduction was 175lb, i.e. a saving of 29%. The new engine should be capable of over 200bhp in tuned form and weigh in at around 423lb. The Healey would challenge again. The new big saloon would have clear technological and performance daylight between itself and the large car from Ford and provide a significant challenge to the cars positioned above it in the market. Would there still have been memories of the prototype twin cam made for Palmer?

Undoubtedly. But no doubt the recent experience of the unreliability of the MGA twin cam mitigated against any more complex valve gear ideas gaining management sanction. Now quite whether the description above is an over simplification of the motives for the decision is obviously debatable. The execution is not. A management decision was made at the highest level – this ‘master plan’ was funded.

And now to the execution of the final act. It is probably difficult to find another major redesign of an engine that achieved such a disastrous final outcome. Particularly one in which so much was spent on new tooling and re-tooling. So much spent for exactly what?

If more power and lighter weight were the mission then these should be easy to identify. The quoted power outputs of the MGC and Austin 3-Litre variants are 145bhp and 125bhp. The 137bhp MGB V8 turns in higher top speeds in the road tests, than the MGC. The Austin 3-Litre, now boasting five more bhp than the automatic VDP 3-Litre tested by the Autocar manages to be 8mph slower in mean max. So this tends to indicate that the embarrassment of bringing out a car six years after its predecessor, with inferior engine performance was too great a burden to bear in open and honest publication of the genuine engine power output.

The facts of measured car performance would indicate that figures of around 105 and 130bhp were closer to the mark for the saloon and sports car engines. But what about that other significant gain to be achieved – using all those expensive new tools on die-cast aluminium components around the engine and thin-wall casting techniques of the crankcase and head.

The final weight saving was just 45lb, a measly 7.5%. Fifteen years on from the original launch of the C-Series and market standards in terms of specific outputs of torque and bhp per litre and importantly torque and bhp per lb of engine, were significantly advanced In performance terms, the engine had not only missed its target, it was actually a retrograde step on a very conservative design from 15 years before!

And what of the original C-Series engines strong suit – reliability and economy for class? Critically one component carried forward was the oil-pump. One needed to save tooling costs where possible. Sadly what was an excellent oil supply for a four bearing crank did not appear quite so good for seven bearings. Dispute apparently raged. Engines failed early. Now the bottom end was ‘weak’. Blame and counter charge were levelled.

One defence was that when the MGC braked from its new, very high speed, oil surged forward in the sump and the pump then ran dry. More baffles in the sump were the answer. The counter was that the output of the pump was just not high enough. Premature engine failure in Austin 3-Litre, against which the ‘prolonged braking from very high speed’ charge could not possibly be levelled, seemed to support the ‘lack of output to feed seven mains’ argument. However it all became theoretical. Nothing was going to be done because neither car was selling and BMC now had some new ‘friends’ with far better offerings.

As for economy, the MGC was akin to the Healey 3000 and probably high figures for mpg were a fairly low priority for all owners. Sadly the Austin 3-Litre was significantly less economic than the A99, 6/99 and VP 3-Litre of nearly a decade before, and each of which was better than the 3-Litre on performance. Twin 1¾ SUs consuming more petrol but producing less power, were needed to keep the new 3-Litre within touching distance of its dated antecedent running on twin 1½ins. This together with self levelling pumps and standard fit power steering all took their toll. Fuel consumption of the new car, just like performance, was worse than the model launched 10 years earlier.

In terms of achievement, it is hard to recall a more negative result having been earned at such cost. A conservative design of 1952 with excellent reliability and good economy had been entirely retooled, with the aim of producing more power and a lighter engine.

Courtesy of an entirely new block, an entirely new head, and entirely new crank, new pistons, new con rods, new manifolding, new camshaft, revised timing gears, new tappets, new die castings for backplate and timing cover and a host of other items, exactly what was the result? A less powerful, thirstier and more unreliable engine. Weight reduction was so pitiful that the engine was totally outclassed by contemporary designs in terms ofbhp/lb.

The saloon was dead in the water at a launch which cruelly coincided with that of the first XJ6. (timing courtesy of the hand of Sir William now he is newly ensconced on the board of BMH? The pretty girl at the party standing very close to plain Jane? All the board members would know who was responsible for the better car. After such a debacle Sir William had burned into his fellow board members minds his requirement that large saloons were now the unique province of Jaguar in the new organisation.) The MGC filled a niche market and offered the buyer with enough money in his pocket to buy more than an MGB, the opportunity to do exactly that. 9992 3-Litres were produced and 9002 MGCs. A total of 18,000 engines gave witness to the last hurrah of the C-Series engine. Undoubtedly it was an economic failure of the highest order. The tooling cost per engine would have been astronomic regardless of all the special componentry and development costs of both cars.

And what of the Coventry Morris Motors plant? The recriminations regarding the failure of the new C-Series engine were keenly felt. There were mistakes a plenty, enough to be shared amongst all participants. In the early 70s with no production of C-Series engines, but A-Series engines being produced in good numbers, the plant was designated the centre for all ‘engine reconditioning’. All Gold Seal engine production was centred there. These were high quality replacement engines to be sold through the dealer network – engines reconditioned to nearly ‘as new’ condition.

They had a high reputation. That such a volume of them was needed appeared to be lost on BL management. In a final charge, the marketing boys came up with another ruse. A cheaper ‘Silver Seal’ reconditioned engine. Not quite ‘as new’ as the ‘as new’ Gold Seal but ‘nearly as good as ‘as new” . With such great demand for reconditioned engines there surely was room for two official versions – a new twist to badge engineering – select a route through two paint booth options. Tangled management , incapable of demonstrating vision, confused sales, marketing and support structures – there was no strategy, no tactics and no future.

A-Series engine production continued at the site to the end but there was no further significant investment in the site and it is surprising that it took until 1982 before there was the management determination to close it down.

In the long view and ultimate demise of everything, it is easy to look back and say did it matter whether one plant closed sooner rather than later? It is also easy for armchair strategists to point out what decisions should have been made when, in 1963 as the 3-Litre was being designed, there was no sign of the later merger with Leyland.

Rover and Triumph were the rivals every bit as much as Ford. Triumph worked hard with innovation and facelifts on its TR series in a way that Austin failed to do with the Healey. The big BMC salons were modestly successful. As solid, reliable and competent cars they secured the ‘directors car’ end of the product line up. In terms Ford marketing understood far better, they provided an aspiration peak through the brand product chain, promoting life long brand loyalty. The market niche most surely existed above the Ford Zodiac Zephyr for a contemporary design that could push the dated offerings from Rover, Humber and Vauxhall out of the market.

BMC was right to try something. The principle of a lighter and more powerful engine was exactly the right way to go.

However, just as in 1952, when, against the urgent need for a conservative design specification, the execution was exactly right, in the mid-1960s the execution was a case study in exactly how not to do it. Miss every performance target and then deliver it late.

We can muse: 2.9-litre, single overhead cam, crossflow, iron block, alloy head. Perhaps even single cam and hemi-head with short rockers driving one side? The services of Edward Turner were no longer required for the design of Daimler engines after 1960. His 2.5-litre V8 used pushrods to excellent effect in part hemispherical heads and Sir William Lyons had decided he had no need of him. If it was not to be Edward Turner then should BMC management have asked Harry Weslake to take a significant role?

With 150bhp for the saloon and 190bhp for the sports car and the weight target hit from a cast iron six, with aluminium head. Entirely feasible at that moment in history. The later 2597cc SOHC Triumph engine fitted to the SD1 had figures of 136bhp @ 5000rpm and 152lb ft @ 3750rom. Use the specific data and scale up to 2912cc and the comparative figures are 152.5bhp and 170.4lb ft.

Was this exactly what the redesigned BMC C-Series engine of 1966 should have looked like? Datsun clearly thought so. Food for thought, certainly. At Morris Motors in Coventry, the view on the shop floor was that they were being led by donkeys and several years before closure, they knew the story would only end one way, regardless of how many colours of paint they sprayed the vast quantities of reconditioned engines going down the line. That those Triumph engines delivered their power via a four-main crank is significant, as is the fact that Datsun went to a non-crossflow two valves per cylinder, inline six with aluminium head, to power its range of vehicles, which so eclipsed the British manufacturers.

We are in the realm of ‘what ifs’. Undoubtedly a 2912cc engine putting out specific figures comparable to the Triumph engines, but released in 1965/6 would have given sales impetus to the big BMC saloon and top of the range BMC sports cars which would have put them back ahead of the competition. Trial the new engine in an old platform for one or two years before releasing the new platform for the new body? It was entirely possible. The money was spent, the design time allocated, all those new tools and patterns were produced. Sadly in execution, the project found a team than was not competent in its delivery.

With the merger of Leyland and BMC, the window of opportunity was closed. The new company would find challenges enough to deal with, well beyond the small scale production of a now uncompetitive, three litre petrol engine and the product lines served by this engine. The quiet death of the BMC C-Series went un-mourned.

The Datsun/Nissan ‘Cedric’ was named after little Lord Fauntleroy – the boy born in poverty, in a far off land who inherits a vast British estate and title and ends up doing a better job as lord of the manor than his antecedents. An excellent choice of name by Katsuji Kawamata the Datsun CEO. Katsuji may well have been having similar dreams to George Harriman. After all, did not George share with us his dream of producing 200 VP 4LRs each week or around 10,000 per year? One of them woke up the next day and managed sound execution to enact the dream.

Nissan Gloria was powered by an engine closely related (and improved from) the BMC C-Series
Nissan Gloria was powered by an engine closely related (and improved from) the BMC C-Series.
Keith Adams


  1. Please excuse the typos and a few mistakes in the above – I should have spent more time proof reading it. At the previous web host – a number of people added a series of very useful comments. Pertinent was that the SOHC 2215cc 6 that preceded the C series was available in single and twin carb states of tune. There was also a very useful comment from someone who worked on the carb set up on the 7 bearing engine. This tied in well with an aspect of the story I did not relate – one of the modifications to the cylinder head was to provide metal so that a drilling could be completed from one side of the head, directly into the exhaust port. This was to allow a belt driven, air compressor to squirt under-bonnet air into the exhaust gases, to assist more full combustion in the exhaust pipe and dilute the noxious gases so that it might meet NAS anti-pollution legislation. The 3 litre and MGC were going to take America by storm ! Sadly they didn’t get that far, despite the plans that they were to do so.

    However why I write – I failed to do my homework but rather took my memory of a P.R. and some none too diligent web searching on my part, at face value. Relative weights of the 4 and 7 main bearing engines. I was looking through an original BMC 3 litre workshop manual and the detail caught my eye.
    Engine weight, standard clutch/torque converter
    Austin 3 litre – (saloon 7 bearing crank) 652/678 lb
    A99 – 110 6/99 – 6/110 VP 3L Mk1 & Mk2 (saloon 5 bearing crank) 598/623 lb
    Refs, AKD 7186 & AKD 4118

    If the measuring conditions are identical – ie all ancillaries fitted – starter, dynamo, carbs, distributor then the new “lightweight” version of the engine was actually 54lb heavier, not lighter as I describe above. I am sorry for the mistake. It makes the final ending of the story even sadder. I can certainly stick a crank or block on the scales but I have only 5 bearing versions around. If someone else could stick a 7 bearing block and crank on the scales we could verify the data.

    • Hi Tony
      With reference to the above story and your comments about the story.
      Having been a great follower of the BMC range being born in 1951 and driven around from about 1957 and later driven fairly often until about 1970 my fathers very capable Shiny Black AUSTIN A90 Six Westminter with all the extra’s on it and because of this today I have 4 Wolseley 6/110’s 3 donor cars and a Mk 1 Auto close to going on the road I found the story very interesting and also sad that the new engine was such a flop I can’t wait to get the enjoyment of cruising at fairly high speed and really appreciating the smoothness and quite of the big heavy engine which obviously absorbed most of the vibration and also the noise compared to much later modern light sixes that were rather noisy and also vibration could also be felt and both engines were turning at virtually the same RPM
      A small comment re your final comment about the early C series engine It was only a 4 bearing crank not 5 as you mentioned but most probably a typo
      Dad finally sold the A90 in 1974 and replaced it with an Executive LEYLAND P 76 V8 which my son still has today

      Thanks for the Good columns above Regards Hugh

  2. Hi Tony,
    Pretty good story of the engines, but a couple of things need correcting.
    The Riley 2.5 engine was not twin overhead cam. It has two camshafts high in the block & operates the valves through short pushrods & rockers.
    There is a typo on the capacity of the 2.6 engine. It is 2639cc, not 2693cc as stated later in the text.
    Only the twin SU’s were bolted directly to the gallery head, the single SU or Zenith had a seperate manifold that bolted to the head where the twin carbs would normally bolt on. It appears the gallery head was an idea borrowed from Nash, & was probably used for cheapness & less parts.
    There was a modification (from Derrington or Downton, I think)which used short bolts in the bottom of the gallery, accessed through larger holes in the top, which were then blanked off. This left the gallery almost unrestricted improving performance & economy. The valve sizes are cosidered too big for the 2639 & are shrouded by the small bore, but worked well on the 2912, so the engine was probably designed initially to have the larger capacity.
    The Riley 2.6 was a badge engineered Wolseley 6/90, rather than a modified Pathfinder.

  3. Tony,

    Good history of the “C” engine.

    Do you have the bore center spacing on the “C” engines?

    Also same dimensions for the “A” and “B” BMC engines?

    Thank you,


  4. Excellent article but may I make a few observations?

    The Austin 2.2litre 4 was enlarged to 2.6 litres for the original Austin Healey (100/4?) and the A90 Atlantic. I understood the change to the C series 6 was forced upon Healey as Austin wished to kill the 4 which was used in the Healey only after the failure of the A90. (It may have been offered in detuned form in the civilian Champ whose Rolls Royce engines were often built by Austin)

    The 2.2 OHC Wolseley engine had a stroke of 87mm (virtually 3.5 inches). Is the bottom end of this engine totally different to the C series?

    The OHC Wolseley engines had proved troublesome and I think required frequent overhaul. Things like induction hardening of valve stems to resist side thrust had to be introduced during production. OHC was not popular due to the complexities of the drive and the difficulty of keeping it quiet. I think the Wolseley drive is by a vertical shaft and bevel gears. One of the major achievements of the Jaguar XK engine in 1948 was to produce a reliable drive for the DOHcamshafts.

    Rover redesigned their 6’s in about 1958 with the introduction of the 3 litre and introduced 7 bearings. This may have put some pressure on BMC.

    Did the appearance of the Austin 3 litre (One of the few cars that looks better from the back than the front)and the MGC (looks the same as a much cheaper ‘B’ apart from an unsightly bonnet bulge which gives no clue about the substantial mods like torsion bar front suspension) have something to do with their failure?

  5. Tony,

    I am seeking a copy of the original drawings/blueprints with dimensions for the type C Austin engine. Do you have access to such drawings or know of a source?

    Jim Hockert
    Dallas, Texas

  6. Aluminum headed / iron block engines suffered gasket creep and were avoided by mass production engine suppliers, notwithstanding the Daimler V8. The triple Weber Rally Healey 2912 C engines deserve at least a passing mention as they were formidable competitors. The Millenial all alloy DMD Australia racing aftermarket C-series engine validates developing conventional but sound engineering.

    Borespan of any four bearing (NOT five) six is usually irregular to account for the alternating mains and empty throws. However the non offset MGC derivation has got to be about equal to the Jag six since their cranks stood up side by side stand virtually as tall (ignoring that the BMC snout is LONGER.

    The mythical Rolls Princess G60 DOHC sounds like the later AJP6 Jag engine in most respects, so why we armchair engineers cannot find even a picture or end view of it is frustrating.

    • Sorry for the delayed comment, have just found the site. As an inquisitive apprentice at Crewe in 1969 engines and parts could still be found from the abandoned Healey 4000 project. Tooling and machining was basically ready when the project was cancelled. I believe 3 preproduction cars were built, one with FB60 engine and 2 with G60. The block like FB60 was B range military but cast in Aluminium with a twin cam head, cam cover was one piece U shaped like Lotus or Alfa. There is an engine at the Rolls-Royce Enthusiasts Club headquarters. So no myth and I might be able to find a B&W picture.

  7. Jim Hockert, your inquiry is best addressed to the aforesaid DMD Australia website as those gents had obtained an original rally alloy C series Healey and done some wonderful pattern work to offer it as an overbore 3.3 or even 3.8 liter engine. Not simply a wet dream, there is at least one of these in serious and reliable race use in North America (and probably elsewhere that rules do not exclude them). Weight is a clean hundred pounds off the original, while outputs well north of 300 bhp from triple Weber DCOEs are certainly seen.

  8. The author of this monograph on the C engine has certainly expended a lot of speculation on the internal politics of a bureaucracy of unenlightened midgets of policymaking. Such turf wars took place at USA carmakers all the time in the absence of, say, an Ed Cole or Zora Duntov to guide a consistent vision.

    The actual engineering discussion and the service problems contained herein is more fertile reportage for my own inquiry. I am struck by the last reference to the Nissan 240Z (L24) SOHC engine, since it has a near external lookalike in its Leyland E series six contemporary. Might anything useful be made of that little developed engine as a Healey motivator?

  9. I might have added the names of Bob Lutz and John DeLorean as curmudgeons with vision who wielded their corporate power without apparent trepidation.

  10. The recent mention of the Healy 3000 & Z series Datsun are interesting, as the headline of one of the first roadtests of a Z series proclaimed that “The Big Healy Lives!”

  11. I really beleived that the the 240 Z engine was a stretched four that was originally a mercedes product copy

  12. The Nissan L engines – the ones in the 240Z, and various – came from Prince, not Nissan. Nissan’s straight six in the early Cedric was an OHV, not OHC design, at this era before the Prince engines were used.

    Looking at pictures of the L vs. Mercedes’ contemporary designs, they look ‘similar’ in terms of cam housing, but different elsewhere – for example, the M180 is where the logical source of a Prince or Nissan OHC licenced engine from MB would be, and the blocks look quite different.

    I can’t find technical drawings of the C quickly, but my wild guess is that the G and L series at best may have a relationship to the BMC units in terms of origin, and then the Mercedes link may be in OHC ‘concepts’, but not necessarily an outright clone.

    And yes, I’d been told the same when I had a Laurel. Had I cared enough to look, the fact that the porting is on the left of the Datsun and right of the Mercedes, the oil filter in a totally different location, the drive for the distributor apparently in a different location that would suggest it’s not the same shared oil pump/distributor drive, the passing similarity to the cam cover shape would probably have made me question it then too!

    If anything, the Nissan G/L looks like a six cylinder version of the J-series (which existed, the K engine used in the early Cedric) with an OHC head. But with the Prince connection, and my inability to read Japanese and REALLY research the native information on where these components originated, it’s hard to tell.

    One source suggests Nissan’s agreement with Austin (which ended in 1959 if said site is correct?) involved exchange of improvements Nissan made as they moved to local manufacturing, and approval by Austin of these components.

    It does seem common, and disingenuous, to assume Asia/Russia et al were simply incapable of producing engineers and designers with their own ideas and had to copy everything, and even, still do. A car company with a foundry in an advanced nation (but not an English one) producing an engine to their own design after a decade of producing and improving a car? IMPOSSIBLE, I SAY! 😉

    • Apparently Brian Long’s book on the Datsun 240Z has it the Prince-developed Nissan L16 (that later formed the basis of the L20A and succeeding L 6-cylinders) was basically a 4-cylinder version of the Mercedes-Benz M180 inline-6, which was built under licence before the Nissan takeover with the author even going as far as to claim the L unit was almost the same as the original M180 engine.

      It is also worth noting it seems the L unit’s descendants includes the Nissan Z/FJ/KA/NA inline-4 and Nissan RB/RD inline-6 engines.

      Meanwhile the Mercedes-Benz M180’s descendants appear to include the M121/M115 inline-4 petrol and OM621/OM616/OM617 diesel units, the OM617 inline-5 diesel as well as the M180-derived M127/M129/M114/M130/M123 inline-6 petrols. Overall both companies certainly extracted much potential out of the M180 in one form or another, with both their engines (and distant relations) achieving long production lives.

      Not sure if the M100/M116/M117 V8s shared any relation with the smaller Mercedes-Benz engines, however Karl Ludvigsen’s book on V12s does make mention of Mercedes investigating a 90-degree V12 version of the M100 V8 (known as the M101) for the Pullman (with the M100 being originally conceived as a 5-litre V8 before it grew in displacement) as well as other proposals for M117 V8-based V10/V12 engines.

      While the Prince-developed M180-derived Nissan L engine is one possible template the BMC C-Series could have followed (despite the latter itself being in essence an enlarged overhead valve development of the earlier 2.2 L Straight-6 overhead camshaft engine – see Jon Pressnell’s book on Morris), the Australian-built Ford Straight-6 engine’s evolution into the Ford Barra DOHC (via an earlier SOHC variant) is another potential template for an alternate C-Series could have followed.

      • Another curiosity would be the Prince-developed Nissan W64 V8 engine, however apart from comparable displacement with the Mercedes-Benz M100 V8 cannot see any connection between the two large V8s given the W64 featured OHVs while the M100 feature a SOHC.

  13. Was the Twin-Cam C-Series a 2.6 or 3.0? Other sources state the former while Palmer’s Auto-Architect states the latter.

    Also though it is speculative, what figures could a hypothetical Twin-Cam C-Series put out compared to the existing C-Series as fitted in the Big Healeys and MGC?

  14. Does anyone remember Abingdon Special Tuning? It was an early day AMG for the working man. Out of BMC’s own factories came hotted up versions of their family cars. They came in three upgrades – stages 1, 2 and 3. I drove a stage 1 mini cooper and I was impressed.

    Special Tuning got their hands on the Austin 3 litre and put three SU’s on the thing. I cannot remember if they altered the timing. I do think they modified the head. It was reviewed in either Autocar or Motor magazine. I read this story as a school boy – so it is a long time ago!

    The transformation in performance was stunning. Not only could this old plodder get to 60 m.p.h in under 10 seconds its fuel consumption was vastly improved! The engine was also smoother to drive. Alas I cannot remember any more.

    I drove a standard 3 litre auto once. It was a pretty old car by then. My memory of it was that it was completely gutless. I also thought that, despite all the wood the interior was no match for the quality of the Humber Super Snipe. My father had one of these and I remember it had much more get up and go as well.

    Of couse it should have been strangled at birth. But having committed to production it should have been developed or the money spent expanding the production of the Rover/Buick V8. Yes it woukd have competed with cars in the fold but it would also, with keen pricing, taken sales from other manufactures. And BMH might have seen a return on their investment.

  15. Reckon the 2.6-2.9 C-Series OHV shares a lot more with the Morris side-valve / Wolseley OHC 2215cc unit then many realise.

    1) There were stillborn plans in the works to produce a bored-out 100 hp + 3.5/4.0-litre OHC version to target “Empire” markets like the US and Australia during the early/mid-1940s.

    2) Morris later developed a 1750cc OHV prototype version of the Morris Oxford MO 1476cc side-valve engine (that itself is related to the larger 2215cc engine), which powering the Morris Oxford II apparently allowed the car to do around 100 mph on the autobahn.

    3) In a period where BMC was rationalizing its engines and given that a 4-cylinder version of the 2.6 C-Series comes to a capacity of around 1750-1760cc, one could logically assume that Morris would not have considered developing the 1750cc OHV unit to start with unless they could argue on the grounds of cost that it shared much with the C-Series.

  16. I did cross my mind that it was unusual there wasn’t a 4 cylinder C series, considering a lot of straight 6s seem to be based on a 4 cylinder unit.

    Also interesting was the C series was OHV when the previous engine had both side valve & OHC versions.

    • Apparently Abingdon did look at a 2.0 4-cylinder C-Series (derived from the 3.0 6-cylinder) for use in the MGB before settling for the 1.8 B-Series.

      Can understand why the OHC was ditched given the reliability issues, more interested to know why Morris post-war never considered OHV versions of the 1476cc 4-cylinder / 2215cc 6-cylinder in place of the side-valve units given that the latter was quickly going out of fashion at the time in favor of OHV.

  17. There’s a fairly large error in the article.. Riley engines weren’t DOHC. The twin cams were in the block, with pushrods and rockers working the valves.

  18. Hi Boo, I am happy to be corrected, thank you, and apologise for the mistake in relation to the Riley 2.5. However, regardless of position of the cams, the styling was not contemporary and the 2.5 Riley did not sell in enough numbers to be economically viable. Now, over 60 years later, the fact that when new, it had appearances that were 10 years out of date is somewhat lost on us, it looks gorgeous and quaint, like many old cars.

  19. While have read BMC commissioned the British Aluminum Company to build an all-alloy A-Series, why didn’t BMC commission them to also investigate lightened or even all-alloy versions of the C-Series and B-Series engines both of which could have really benefited from a significant reducing in weight?

    • Probably the same reason that a lot of other developments didn’t happen at BMC – bad management. A huge amount of work supposedly went into the V4 engines but was dropped because of Alec stating they were not needed in FWD cars – funny that Lancia used them very successfully!

      • Understand it being down to bad management, just that both the C-Series and the B-Series were unfavorably compared to the all-alloy Rover V8 in terms of weight.

        Even the large 4-litre 6-cylinder Austin “D-Series” in the Austin Princess and Jensen 541 would have benefited from a significantly lightened / all-alloy version where the extra cost of such an engine would matter very little at that segment, possibly with more input from one Tadek Marek who before moving to Aston Martin was allegedly involved in the development of the C-Series engine.

        Thought the problem of the narrow-angle V4/V6 project was down to tooling costs and the fact they could not be mounted transversely only longitudinally in Issigonis’s FWD cars?

  20. They did indeed cast some aluminium heads for the 4 main engine for use on the AH3000 rally program and the brothers at Southern Carbs replicated these in the late 80s. Not sure what the downsides were, but that was not the answer. The inline six with a pushrod operated valve train, as configured, was fine in 1952 but 16 years later it needed a significantly different solution path to the one they chose.

  21. The following link mentions the C-Series designation was originally intended for a pre-BMC Austin designed inline-6 version of the Austin A40 1200cc engine displacing around 2-litres, with the intention of using as many common parts as possible to keep to keep manufacturing costs as low as was consistent with reliability and servicing costs of the units.

    However the A40-derived 6-cylinder engine was not approved for production, because of the presence of the 2199cc 4-cylinder unit used in the Austin 16 HP / Austin A70 (called BS1 or unofficially “D-Series” as it was derived from the 3.5-4-litre 6-cylinder “D-Series” unit originally conceived as a truck engine prior to appearing in the post-war Austin Sheerline).


  22. I was told any years ago that the Austin A90 six cylinder engine was a sort of Austinisded Standard/Jaguar six but a different head to the Weslake designed o.h.v.
    Robin Martin, Birstall, Leicester 06/04/21

    • I don’t think there was any connection between the Standard/Jaguar pushrod cars and the C series. The Jaguar IIRC was 7 bearing, ( as had been its sidevalve predecessor ) and the head was crossflow, and it was a much more undersquare engine than the C series which gave it considerable torque at the expense of a low rpm limit which I recall was 4500 rpm redline on both 2.5 and 3.5 versions

  23. I just wondered if anyone would know if an Austin A90 Westminster BMC-C series engine would fit in a 1958 Morris isis series 2? The engine in the Morris is beyond repair. From what I can see it seems the same, although the starter motor is placed on the other side, in which case I am hoping the starter motor plate could be swapped from the Isis BMC-C engine to the A90? Any info would be much appreciated.

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