The Nordec 10 cc Motors

(the "British McCoys")

by Adrian Duncan

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The term The Real McCoy has passed into general use in the English-speaking world as an expression denoting "the real thing" or "the genuine article". The term has always had a special connotation among powered model aircraft enthusiasts of "classic" vintage (like myself) since it immediately brings to mind the deservedly famous McCoy line of model racing engines originally designed in the mid and late 1940's by the legendary Dick McCoy and used with great success by competition modellers the world over for the subsequent two decades.

Here we focus on an engine that is most definitely not the Real McCoy in a modelling sense, although at first sight one might almost (but not quite) be forgiven for mistaking it for the genuine article! This is the British-made Nordec 10 cc racing engine of the late 1940's; an all-British production in manufacturing terms, but which undeniably drew its design inspiration from the McCoy racing engines.

Before we embark upon our story, I wish to thank my friend and colleague Alan Strutt, who has provided an immense amount of help in the preparation of this article. I couldn’t have completed this study without Alan’s generous assistance, and I’m pleased to acknowledge it here. Several others have assisted by providing serial numbers, and their contributions are noted in the following text. Thanks to one and all!

Background

The Nordec model engines were manufactured by the North Downs Engineering Company Ltd. (referred to hereafter as "Nordec"). At the time in question, the company operated from premises on Godstone Road in the quaintly-named district of Whyteleafe, Surrey. This was in effect a sub-district of the community of Warlingham, which lies a little to the south of Croydon in South London.

According to a friend of Alan Strutt’s who lived at nearby Caterham at the time in question, the main business of the North Downs Engineering Company was car sales. The parents of Alan’s friend apparently bought several new cars from them following WW2. However, they also had a strong presence in the automotive engineering business as well, going so far as to actually make a few Ford-based sportscars under the Nordec name in 1949. (Insert image of Nordec car)

The Nordec engines were introduced in early or mid 1948—the precise date is obscure. Although the company was completely new to the manufacture of model engines, this was no start-up effort by a brand-new manufacturer. The Nordec company was already well-established in the precision engineering field and indeed had become quite famous in automotive circles for its production of the Marshall-Nordec supercharger kits for full-sized automotive use. These kits were based on the use of a Marshall low-pressure Rootes-type compressor along with suitable hardware manufactured by Nordec to marry the system to a variety of standard road cars of the period. The production and installation of these kits involved precision engineering of a very high order and the company had built up a steady business and a solid reputation on the strength of these products.

It is unclear why Nordec chose to enter the model engine manufacturing arena when its bread-and-butter business was already well established and thriving in an entirely different field. The fact that it chose to enter a new field of endeavour with something as specialized as a 10 cc racing engine is also a bit puzzling as engines of this displacement, purpose and cost could not reasonably be expected to generate mass sales at any time. Not only was the British model engine market small by comparison with that in the USA, the post-war domestic economy was relatively cash-starved. From rational hindsight, this surely would have argued against the company generating any significant additional cash flow from the model engine venture.

It was presumably for these reasons that other British model engine manufacturers of the period had steered clear of the 10 cc field. Consequently, the sole British competitor to the 1948 introduction of the Nordec was the Rowell 60 from Scotland, so there may have been a not-unreasonable perception that a market niche existed. The make-or-break issue was the potential size of that market niche.

However you look at it, these considerations imply that this was in fact something of a "labour of love" and that someone in a position of some authority within the company was a keen model aircraft enthusiast who influenced the company's decision to become involved in a field of his favourite hobby in which there appeared to be a small but nonetheless identifiable market niche. Not knowing the names of the personalities involved, we can't comment further on this notion beyond stating that it appears to be a strong possibility based on the surrounding circumstances.

From a purely financial standpoint, the decision to enter the model engine field was doubtless eased considerably by the fact that the company already had a well-established cash flow based upon the thriving supercharger business. Hence their entry into the new market area was by no means a "do or die" venture in economic terms. And, as we shall see in due course, the company was to survive in business long after their relatively short-lived production of model engines ceased.

Lawerence Sparey, in his March 1949 Aeromodeller test of the glow-plug Nordec, states the price as being in the vicinity of £12.00. This was a small fortune in those far-off days of the immediate post WWII period in Britain. Judging by this, it appears that the company philosophy was to produce a quality product, sell it at a price which allowed a reasonable economic return and see if the market would respond. If it did, the company would make a nice little bit of extra income. If it didn't, they stood to loose the tooling and development investment, but they had a plan that would keep this to a minimum. A mitigating factor to this price may have been the hefty Customs Tax being levied on imported engines and the lack of local spares availability for them.

Having decided to enter the field with a 10 cc racing engine, they very sensibly saw no need to spend the time and money normally required to develop a new design from scratch. The company only had to look across the Atlantic Ocean to find a proven prototype already developed and in production. This was of course the 1946-47 version of the highly successful McCoy 60 Red Head racing engine, then in full-scale production by the Duro-Matic Products Company of Hollywood, California and was already establishing itself as a design to be reckoned with in the highly competitive performance fields of control line speed and model car racing.

At first sight, it might seem a little odd for Nordec to have elected to go so openly head to head and hence invite comparison with an established line like McCoy, particularly in a rather specialized field in which there was already strong competition from the likes of Hornet, Ball, Orr, Bungay, Hassad, Dooling and others. However, an understanding of this matter requires that it be looked at from the contemporary British perspective. These American designs were competing amongst each other for a share of a vast and well-heeled domestic market in the USA. The continental United States had been spared the direct impacts of war upon its civilian population and domestic infrastructure. Hence post-war America was booming, in contrast to war-ravaged Britain. So there were potential domestic buyers for all the engines that American industry could produce, without the need to look to a minor export market like that which then existed in Britain.

As a result, large American racing engines were essentially unknown in late 1940's Britain when Nordec was planning their market entry with such a model. Few British modellers at the time would have so much as seen a McCoy 60, let alone a Ball, Hassad or Bungay, so there was considerably less opportunity for direct comparison than might be imagined. The relatively few American racing engines that did reach Britain during this period were either brought over by American service personnel or were personally imported by a select few British flyers having the means and contacts to do so.

The consequence of this was that there was really very little competition for the Nordec at the time of its arrival, either domestically or through the import route. It is true that the excellent Rowell 60 racing engine from Dundee in Scotland was introduced at more or less the same time to meet a similar market niche, but even that fine engine represented relatively minimal competition in an aeromodelling sense because it was primarily intended for model racing car use and its weight of 19 ounces was a near-insuperable impediment to its successful use in model aircraft. That said, I have a personal recollection from around 1961 of seeing one of my club-mates in Sheffield still using a modified Rowell in a C/L speed model, albeit with rather indifferent results by the standards of the day. But that's another story...

So the Nordec more or less had the British 10 cc model aircraft racing engine market to itself at the time of its introduction. Viewed from that perspective, it becomes a little easier to see why someone at Nordec was able to persuade the directors that there was a market niche to be filled in that displacement category. Let's look at the initial products with which the Nordec company hoped to tap into this niche.

The early Nordecs

We have noted that the Nordec engines were very much based upon the tried and tested design of the contemporary McCoy 60 model. At this point, it's important to recall that in 1947 and early 1948 when the original Nordec designs were evidently being developed, the contemporary McCoy was not the later all-conquering Series 20 model which appeared in 1948 but was still the spark-ignition 1946-47 Red Head 60 (ECJ #5) with black-anodized case, red head, rear disc induction and relatively restricted porting by later standards. The unknown Nordec designer clearly took a long hard look at this version of the McCoy and based his design very much upon that motor. However, he did introduce a number of changes of varying effectiveness.

One factor requiring consideration (which McCoy was even then in the process of evaluating) was the issue of the ignition system. As of late 1947 when development of the Nordec was in progress, the glow-plug had only just been refined by Ray Arden into its commercial form in the USA, and at the time of the Nordec's release in 1948 modellers were still divided on the subject of whether or not the new form of ignition was in fact superior in strictly performance terms, particularly for all-out competition applications. The very precise ignition timing adjustment permitted by the use of an adjustable timer was a factor which many saw as a performance advantage of the spark ignition configuration, although the elimination of the weight penalty of the spark ignition system was of course widely recognized as a major benefit of glow-plug ignition. As events were to prove, the glow-plug was destined to sweep the spark ignition engine aside and become the standard very quickly. Sixty years later, it's all too easy to forget that this was not yet obvious in 1948.

Nonetheless, the attractions of the new form of ignition with its far greater simplicity were by no means lost upon British modellers. British engine manufacturers were quick to respond, although they did so rather half-heartedly for the most part by adapting existing diesel or spark-ignition designs to glow-plug operation rather than developing new tailor-made designs. ED supplied a glow-plug conversion kit with their 2.47 cc Mk. III diesel which first appeared in early 1948, and International Model Aircraft rapidly developing a glow-plug version of their Frog 175 spark ignition engine, which was to appear in mid 1948 as the Frog 160. Davies-Charlton Limited offered an ED-inspired glow-plug conversion head for their 5 cc Wildcat diesel and in general, the profile of the glow-plug engine was on the rise in British modelling circles, albeit lagging somewhat behind the level of interest in America.

The rising interest in glow-plug ignition was not lost upon British accessory manufacturers, and a reliable indication of the rapid development of a demand in Britain for glow-plugs may be derived from the fact that by the end of 1948 no fewer than three British firms were engaged in the manufacture and/or marketing of glow-plugs. The first and most significant of these was the large and well-established automotive firm of Smith's Motor Accessories Ltd, who found it worthwhile in 1948 to have their subsidiary K.L.G. Sparking Plugs Ltd commence production of the famous "Miniglow" plugs in various sizes. These were to become something of an icon in British modelling circles and were destined to remain on the market for several decades (don't mistake them for Arden plugs, upon which they were most likely modelled). Col. Bowden reported that as of late 1948 British-made glow plugs were also being offered under the McCoy Hotpoint label as well as by the then-emerging firm of Keil Kraft. The actual manufacturers of the latter two plug brands are unclear at this distance in time.

All of this clearly highlighted glow-plug ignition as an emerging factor in the British modelling scene that could not be ignored by a new manufacturer wishing to start off on a forward-looking basis. Consequently, although the Nordec 10 cc racing engine was introduced in spark ignition form at the outset, this model was almost immediately joined by a glow-plug ignition version. Nordec actually appear to have been ahead of McCoy in this respect, since the production glow-plug version of the Series 20 McCoy 60 did not appear until 1949. Interestingly enough, both the spark ignition and glow-plug ignition models of the Nordec remained in production concurrently for much of the engine's admittedly short production life, indicating that there remained a market niche for the sparker even after the introduction of the glow-plug model.

The two models which resulted from this approach were designated the Nordec R10 (spark ignition) and Nordec RG10 (glow-plug) respectively. They were identical in almost all respects, the only real differences being in the front housings. As a result of the close similarity between the two models, it will be convenient to describe them together, noting the differences at the appropriate points.

Before doing so, it is necessary to point out that the descriptions which follow are based upon detailed examination of my own unmodified examples of the R10 and RG10 which are in the configuration in which the engines seem to have been offered for the greater part of their short production life. It appears that the engine as first introduced differed in detail from these examples. The attached illustration taken from Col. C. E. Bowden's January 1949 book entitled "Model Glow Plug Engines" shows the RG10 engine in its original form. The cooling jacket, venturi and prop driver are all slightly different from their counterparts on the later examples, and the engine is assembled with the exhaust stack on the left. This was not a one-off—the one tested by Lawrence Sparey in early 1949 for "Aeromodeller" magazine (see below) was similarly arranged. Later models (both in contemporary illustrations and in the metal) are uniformly seen with their stacks on the right. But these differences are largely cosmetic in nature, and do not affect the validity of the following descriptions.

Description: Nordec R10 and RG10

We may as well start out by summarizing a few vital statistics. The bore and stroke measurements of both Nordec models were 0.940" and 0.875" respectively for a displacement of 9.95 cc. And yes, if you know your McCoy's you'll recognize these measurements as being exactly those of the McCoy 60! The RG10 weighs in at 15.875 oz, compared with the weight of 15.75 oz. for the glow version of the McCoy 60 Series 20. Near enough—so far, so similar!

There are other direct similarities to the McCoy. The engine is based upon a very sturdy sand-cast crankcase with integral exhaust stack normally assembled on the right hand side, although we have seen that some of the earlier examples of the Nordec appear to have been assembled with their stacks on the left. Like the McCoy "original", the crankcase is given a very durable black finish on its un-machined surfaces, although the Nordec is painted rather than anodized. The mounting holes are identically spaced, meaning that the Nordec and McCoy are directly interchangeable in the same model.

The cylinder porting and timing is more or less identical to that of the 1946 McCoy, with both transfer and exhaust ports consisting of a series of small square openings separated by thin pillars to prevent ring snag. Two additional round ports are provided on the transfer side which align at bottom dead centre with skirt ports in the piston to augment the flow of gas into the bypass passage. The bypass passage of the Nordec, which is cast into the main crankcase as on the McCoy, is somewhat smaller in area than its 1946 McCoy counterpart and probably needs all the assistance that the skirt ports can give it!

The Nordec's cast light alloy piston is of a very similar design to that of the McCoy, with two well-fitted compression rings and a contoured crown incorporating a baffle. The crown on the Nordec is somewhat less elevated than that of the McCoy, presumably to better conform to the somewhat different combustion chamber configuration (of which more later).

Induction arrangements are also more or less identical, with a sand-cast aluminium alloy disc valve mounted on a steel shaft which in turn is very well supported in a bearing formed in the cast aluminium alloy backplate. This is timed (on my examples at least) to open around 45° after bottom dead centre and close approximately 55° after top dead centre—a fairly generous induction period of 190°. The venturi is a separate component which mounts onto the backplate, just as on the McCoy. A surface jet needle valve assembly is used with a gland nut for needle tension, again very similar to that employed on the McCoy.

The crankshaft is carried in two ball bearings which are mounted in a detachable front housing held in place by four 4BA Allen head screws. Apart from the thread used, this again follows McCoy practise exactly. A bobbin-style prop drive is used, and this too follows McCoy practise in being secured to the shaft using a Woodruff key. The early Nordecs used a driver with two studs protruding from the drive face to grip the prop as opposed to the milled striations which were used on the later models.

OK, so much for the similarities! What about the differences? Well, as it turns out, there are actually more of these than we might expect from a mere "clone"!

Starting at the top, the plain aluminium alloy cylinder head of the original Nordec is not a casting as used in the McCoy but instead is machined from solid bar. This has one rather unfortunate effect—it presents a significant production challenge in connection with the matching of the shape of the underside of the head to the piston crown, given that the ideal shape is significantly asymmetrical in all three dimensions. And indeed no attempt has been made to create a matching shape and hence a more efficient combustion chamber. The underside of the cylinder head is simply turned into a bowl shape with a narrow and clearly ineffective "squish band" at the edge and a broad slot milled across at the appropriate point to provide baffle clearance. This head conforms only marginally to the piston crown, and the resulting inefficient low-swirl combustion chamber with numerous "gas pockets" was one of the Achilles Heels of the Nordec in performance terms, as events were to prove.

There were two distinct head configurations available for the Nordec. Externally, these appear identical. However, the combustion chamber "bowls" of the two head types are cut to different depths to give a choice of compression ratios. The low-compression head naturally has a deeper bowl machined into its underside to increase the combustion chamber volume at top dead centre, and this has the effect of reducing the head thickness available for the plug threads. Consequently, the low compression head is intended for use with a shorter-reach plug than the high compression version. The low compression head is externally identified by having a letter "S" stamped into the horizontal surface of the plug recess. The high compression head (reportedly 10:1) is externally unmarked.

The instruction manual makes a particular point of this, stating that heads having the letter "S" stamped into them should be fitted with a plug having no more than a 5/32" reach, while unmarked heads may be fitted with a longer-reach plug having a reach of 7/32". My own glow ignition model RG10 is fitted with the low-compression head, while my spark ignition R10 model has the high compression item. By "feel", the difference in compression ratios is considerable—if the high compression head is 10:1 as reported by Sparey, then I'd guess that the low compression head is in the 7.5:1 range. The cylinder heads on both engines are fitted without gaskets, the contact surfaces being lapped together to create a good seal.

Moving on downwards, we come to one of the major structural design differences between the McCoy and the Nordec. It isn't at all apparent until you take one apart, but the finned cooling jacket is not integral with the main crankcase casting. It is in fact a separate turning which slips over the lower cylinder liner and supports the flange at the top of the liner. The lower end of this jacket rests on the upper surface of the main casting, which is turned flat at the top of the wide turned band visible above the top surface of the exhaust stack. Hold-down stresses are transferred to the top of the main casting through this separate cooling jacket, with the Meehanite liner itself remaining unstressed apart from the flange at the top.

Naturally, this requires the six 4BA Allen-head hold-down bolts to pass completely through both head and cooling jacket and thread directly into the main casting below the jacket. It's not completely clear why the Nordec designer made this change, but it does make the main casting a little smaller and also eases the task of forming the cooling fins on a simple lathe setting using solid bar—less machining on the main casting with its more complex lathe set-up. I suspect that the decision to adopt this arrangement was production-based.

The outside diameter of the cooling fins on the early Nordecs seem to have been turned to a uniform measurement which matched the cylinder head. This can clearly be seen in Col. Bowden's illustration reproduced above. Later models like my own illustrated examples featured a slightly tapered form applied to the fins so that they matched the head diameter at the top and the slightly smaller case diameter at the base.

The rest of the cylinder/piston/rod set-up is more or less similar to the McCoy, down to the sturdy forged con-rod with bronze-bushed big end and nominally-identical working length between centres. For our next set of differences, we must look to the front end assembly. Here we immediately notice one production change of some significance—the Nordec crankshaft is a built-up item rather than a one-piece item as used on the McCoy. The crankweb is a separate component which is press-fitted onto the crankshaft. This can be clearly seen in the comparison view of the McCoy and Nordec crankshafts, as can the different shape of the counterbalance portions of the two crankwebs.

The front housing of the Nordec is not machined from the solid as one might suppose upon first acquaintance but is machined from a sand-casting of more-or-less identical section to the front face of the crankcase. This casting is machined virtually all over, the original as-cast surface being visible only at the edge of the mounting flange on the glow model. It is interesting to note that the castings used for the glow and spark ignition models were completely different—the casting for the spark ignition version incorporated the opening for the cam follower as cast, whilst that for the glow model naturally omitted this opening. On the sparker, the original as-cast surface is exposed in the cam follower opening as well as around the rim of the mounting flange.

The front housing mounting holes of the Nordec and McCoy engines are identically spaced, and the McCoy front end can be bolted right onto the Nordec case. However, you couldn't run it this way—the locating spigot which extends into the case and contains the rear bearing is very slightly smaller on the McCoy than it is on the Nordec, so the McCoy front end is inadequately supported in the Nordec case for running purposes. The Nordec unit is a very accurate plug fit in the case and thus offers excellent shaft support when assembled.

The Nordec bobbin-style prop driver extends further forward than that of the McCoy, which could be an advantage for speed model installations. Like the McCoy, this driver is locked to the 0.375" diameter front portion of the shaft with a Woodruff key, which is of very generous proportions on the Nordec. However, the method of prop mounting is rather different, at least on the later Nordecs. The McCoy uses the familiar hub nut which passes through the prop hub, screws onto an externally threaded extension at the front of the shaft and enters the bore of the prop driver, thus locating the prop very securely. The early Nordecs like the one illustrated by Col. Bowden used a similar set-up. However, subsequent examples of the Nordec used a seemingly rather inadequate 2BA hexagonal-head bolt with a thin steel washer. The bolt threads into a tapped hole in the centre of the crankshaft. This arrangement appears on both of my own illustrated examples of the R10 and RG10 as well as on the example tested in March 1949 by Sparey, and is also consistently seen in contemporary photographs of these models. One can only wonder, why?!

The 0.187" outside diameter of the 2BA bolt is of course totally inadequate for the mounting of a suitable prop for this rather large engine, and it's quite clear that the intent was for the user to incorporate an alloy tube which is drilled out internally to accommodate the prop bolt and turned externally to a close fit in the 0.375" diameter bore of the prop driver bobbin, thus locating the prop hub very securely relative to the bobbin driver and shaft without relying on the bolt for lateral security. This tube is generally missing from examples of this engine encountered today, but its use is not really optional if a secure prop mounting is desired. Both of my examples have such fittings, as did another example which I had years ago but then sold. I would not run a Nordec without it.

The final differences are to be found at the rear of the engine The intake venturi is not threaded directly into the backplate as on the McCoy but instead is turned to a plug fit in a socket machined concentric with the intake, where it is secured using a 4BA set screw. On my example of the R10 sparker, this set screw is a neat Allen-head item, whereas on my RG10 glow model it is a standard slot-head screw. This arrangement is actually superior to the McCoy system when it comes to adjusting the position of the needle to suit different installations. The bore of the venturi on the Nordec is somewhat smaller than that of the 1946/47 McCoy at 0.312" and actually looks to be rather undersized for an engine of this displacement. This doubtless has something to do with the Nordec's undeniably inferior performance in comparative terms. The amount of metal which forms the spigot section of the venturi is too small to allow for a really significant enlargement, although some extra power could doubtless be obtained that way.

The needle valve assembly is pretty much a clone of the McCoy set-up, using a separate fuel jet which screws into one side of the venturi and a needle mounting which screws into the opposite side. A straight needle is used, with a knurled brass knob at the outer end. A gland nut is used for needle tension.

Finally, the Nordec venturi itself is a little shorter than that on the McCoy, which has the benefit of allowing the engine to be mounted a little closer to the main firewall. It's also worth noting in passing that the early Nordecs used a venturi which was externally far more bell-shaped than the later models. Once again, Col. Bowden's illustration shows this clearly.

So the Nordec certainly borrowed a great deal from the McCoy, but it does show evidence of a certain amount of original thinking, if only in production terms for the most part. The engines are beautifully made throughout, with fits of the highest order and high-quality steel Allen-head screws used for assembly. The sand-castings are a bit rough-surfaced, but certainly well up to the job. Overall, these are very well-made engines which should give excellent service. So how do they work in reality? Let's find out...

Performance and Further Development

The tragedy of the Nordec (if that is the correct term) is that it was in effect copied from a prototype (the 1946/47 McCoy Red Head 60) which was in the process of being drastically upgraded at the very time when the Nordec first reached the market. As a result, its performance was immediately overshadowed by the vastly improved Series 20 version of the McCoy 60 which was introduced in 1948 to replace the model from which the Nordec was copied.

As far as the British modelling press was concerned, the Nordec got off to a very promising start. Col. Bowden made much of the engine in his January 1949 book "Model Glow Plug Engines", stating that the engine filled "a long-felt want in this country". He praised the quality of construction of his own example, and in this at least examination of surviving examples fully bears him out. He reported using his Nordec in a 44 inch long high-speed boat, an illustration of which appeared in the book. Finally, he noted that in 1948 the Nordec had established a British control-line speed record in its class at a shattering 95.3 mph. Nothing there to make Dick McCoy choke on his coffee, but as noted previously there were few if any McCoys in Britain at the time for the Nordec to compete with. Just as well, perhaps...

Following the release of Col. Bowden's book, the RG10 glow-plug version of the Nordec was tested by Lawrence Sparey, the test report being published in the March 1949 issue of Aeromodeller magazine. This was in one respect a historic test—it was the first-ever test by Sparey of a glow-plug model engine. This illustrates the fact that interest in the glow-plug engine in diesel-minded Britain had lagged well behind that in the United States, where the glow-plug engine had been all the rage for well over a year prior to this date.

For a first test of a glow-plug engine, things went very well and Sparey was unstinting in his praise for the engine. He characterized starting as "exceptionally easy" and running qualities as being "free from all fussiness". As a past Nordec user myself, I would endorse both those comments. Sparey praised the engine's response to adjustments of the needle, while commenting also on its prodigious thirst!! He referred most favourably to the quality of the engine's construction and summarized its performance as "excellent, if not remarkable".

The latter statement must be read in the context of measured performances of other contemporary British models. It has to be said that performance standards in Britain at the time generally lagged well behind those in America, particularly in relation to their glow-plug models. The Nordec was entirely typical in this regard and hence was little if any worse than any other contemporary British glow-plug engines in terms of its specific output. The actual peak power measured by Sparey was only 0.48 BHP at 11,200 rpm using a straight 75-25 percent fuel mix of methanol and castor oil. No doubt things would have improved substantially if a proportion of nitro had been added. But at this time in Britain nitro was almost impossible to obtain and prohibitively expensive when it was available, so Sparey was fully justified in using a straight fuel—most British modellers of the period would have had no other option.

Even so, this could scarcely be classified as a true "racing" performance! And it must be said that the figure seems a little suspect to me—an original Nordec RG10 which I owned and used many years ago gave the impression of doing a bit better than this. Mind you, I used a proportion of nitro in my fuel, and that would certainly have improved matters quite a bit. However, there's no question at all that the Nordec failed to approach the performance of the McCoy original. Even the 1946 version of the McCoy developed a measured power output in the order of 1.0 BHP at around 13,000 rpm, and the Nordec certainly didn't approach these figures. And to make matters worse, the Series 20 McCoy 60 introduced in 1948 more or less concurrently with the original Nordec performed at a far higher level than its 1946/47 predecessor upon which the Nordec was based. In essence, the Nordec was out of date in design and performance terms as soon as it was released.

Not to be outdone, Aeromodeller's rival British magazine Model Aircraft published a test of both the R10 and RG10 models which appeared in its June 1949 issue. Although the latter test was unattributed, it was almost certainly carried out by Peter Chinn. A slightly superior power figure to that obtained by Sparey was recorded, the published figures being just over 0.6 BHP at 12,000 rpm on glow-plug ignition as later recalled by Chinn (Model Aircraft, March 1956, Exit the Racing Engine?). But this more or less confirms the fact that the Nordec in its original form was a less than stellar performer by comparison with its competitors, albeit a well-made and fine-handling unit.

The inefficient combustion chamber design noted earlier, coupled with the rather undersized intake and relatively small bypass passage, almost certainly had a great deal to do with the documented shortfall in the Nordec's performance. Despite the more restrictive breathing arrangements, the rest of the engine followed the McCoy design sufficiently closely that one would objectively expect a somewhat narrower performance gap than that which actually resulted. The implication is that the combustion chamber design was a major culprit here.

That said, there's no doubt that the original Nordec was (and is) a very nice engine to handle, especially for such a large unit. Experience fully justifies Sparey's comment that it started very well for a racing engine and ran very smoothly with excellent needle response. The one which I used myself for a while many years ago (just to be different) was always a pleasure to operate if one could accommodate the noise levels and afford to fill the tank!

Despite the use of a surface jet needle valve set-up, suction was actually quite reasonable, doubtless due to the relatively small venturi section used Consequently, the Nordec was used in applications which stretched well beyond those normally expected from a racing motor. Despite its rather excessive weight, it was actually used in large control line stunt models by a few deaf modellers with deep enough pockets to afford the fuel bills, and its running characteristics were surprisingly well suited to this application, particularly if a spraybar was fitted in place of the surface jet system. As an example, the Nordec was featured as the "plan" engine in the large biplane stunt model Yoicks which was published in October 1949 as Aeromodeller plan no. CL334.

But the engine had of course been intended all along for racing use, and its natural métier was the control line speed model. In standard form, it must be said that the engine could scarcely be considered a world-beater in this field. However, it soon received some attention from the tuning experts who were an evolving breed at the time, and the legendary tuner Fred Carter was among those who tried their hand at getting more out of the Nordec than its original configuration allowed.

Carter was among those who recognized the combustion chamber configuration as a major stumbling block to the achievement of the engine's full potential. He focused on this area, making a new piston and head for his Nordec while carrying out relatively minor modifications to the rest of the engine. The results of his efforts were quite tangible—at a time when the stock engine was good for perhaps 100 mph under ideal conditions, Carter's "Little Rocket" consistently turned in speeds of around 116 mph, a fine performance by then-current British standards. This success marked the beginning of Carter's long run of pre-eminence as a racing engine tuner in Britain.

Naturally, the results of the efforts of Carter and his compatriots were not lost on the Nordec company, nor was the lesson missed regarding the inadequacies of the original combustion chamber design. In late 1949 Nordec developed their own revised head design to address this issue. The new head was a casting instead of the machined unit formerly used, and this allowed the provision of a combustion chamber contour which more correctly matched that of the piston crown, thus eliminating the problem of "gas pockets", promoting improved swirl and hence improving combustion efficiency.

The company released an updated version of the engine designated the "Nordec Special" in December of 1949, still in both glow and spark ignition forms. This was more or less identical to the earlier models with the exception of the revised cylinder head. However, the somewhat restrictive porting and induction system remained unaltered, and in consequence the performance of this version still lagged far behind that of the now all-conquering Series 20 McCoy Red Head 60. As a result, the original Nordec Special can hardly be termed a success in performance terms. The marketplace evidently agreed with this assessment, and sales were not brisk.

To their great credit, the company was once again quick to recognize the residual problems with their product, and in the Spring of 1950 they elected to go whole hog and introduce a completely revised model which was quite openly based on the Series 20 McCoy and featured far more open porting arrangements to go along with its improved combustion chamber design. The result was an entirely new model, the Nordec Special Series II. It appears to have been released only as a glow-plug model.

As one might expect given the engine's heritage, the performance of this model was a huge improvement over that of the earlier RG10 and Nordec Special Series I models. Peter Chinn tested the prototype of this model for the manufacturers and also covered both the Series I and Series II versions of the Special in a test report published in the June 1950 issue of Model Aircraft. Published output of the latter model was a highly creditable 1.23 BHP at 15,200 rpm. Now that's more like it!!

By way of comparison, Chinn's published November 1951 test of the Series 20 McCoy found 1.52 BHP at 16,100 rpm. Although this certainly bettered the performance of the stock Nordec Special Series II, it's clear that the latter had finally made it into the same ball-park as its American rival, performance-wise. It had always been a match for the McCoy in terms of quality, so it appeared that Nordec finally had the product that they needed to succeed.

However, it was a case of too little, too late, and the writing was already on the wall for the Nordec series. Sales of large racing engines in Britain were never brisk, a fact which should come as no real surprise, and the company evidently decided very soon after the introduction of the Nordec Special Series II that there was little point in continuing in the field. A contributing factor in this decision was doubtless the late 1950 failure of legal case presented by the model trade to have British-made model goods exempted from Purchase Tax. This unfavourable outcome put a serious dent in the profit and pricing picture for model engine manufacturers in Britain, and it’s doubtful that Nordec were making much on the model engine side even before the failure of the case.

The Nordec Special Series II was therefore produced in very small numbers, and production of the Nordec engines appears to have ceased entirely prior to the end of 1950. Consequently, the Nordec Special series engines are extremely rare today.

So the Nordec racing engine was gone, after a production life of a little over two years. However, this was by no means a body blow to the Nordec company, which remained in the supercharger business long after the cessation of model engine production. It is presently unclear how long the company remained in operation, but it was certainly still in business as of 1959 and operating from a different location on Westway in Caterham, Surrey, just down the road from its former location. At that time it was promoting a revised supercharger system known as the Godfrey-Nordec system in addition to the well-established Marshall-Nordec installation, and was offering kits for such apparently unlikely "muscle cars" as the Austin A35!!

Serial Numbers and Production Volumes

I never recorded the serial number of the Nordec RG 10 that I owned many years ago, but all of my present examples have three-digit serial numbers stamped into the outer end of the left-hand mounting lug.   My one and only R10 sparker bears the number 513, while my lowest-numbered RG10 glow model displays the number 393. I also own a slightly modified but highly serviceable example of the RG10 bearing the serial number 413 and a LN example in near-pristine condition with the number 827. This latter is the highest serial number yet encountered for an original Nordec Series I glow-plug model.  

Some additional serial numbers have come to my attention since this article was first published. A series I Nordec 60 spark ignition motor bearing the serial number 215 appeared in the recent auction of the Walton Collection. A similar glow-plug model bearing the serial number 815 appeared on eBay recently, and reader Kevin Bridges has reported owning engine number 870, which is a spark ignition model which has been converted to glow-plug operation. This latter is the highest serial number yet recorded for a Series I Nordec 60.

Jan Huning of Rugby, England has reported the existence of Nordec spark ignition R10 serial number 463, while OFW Fisher reportedly owned RG10 serial number 427, as noted in his Collector’s Guide to Model Aero Engines. Alan Strutt of Somerset, England, has reported that he has spark ignition engine number 201 (which is also marked "TEST no 4" for some obscure reason). Alan also has a second sparker bearing the serial number 6x1 (middle digit illegible).

An interesting engine in Alan’s collection is RG10 engine number 220 which has been fitted with a Special series piston and head. This is most likely an owner upgrade. In addition to several complete engines, Alan has a number of individual components including factory crankcase number 6. This is important in that it confirms that the numbering sequence started at 1. There’s no way of knowing whether it originally formed part of a glow or spark ignition model.  

As far as the Special Series II goes, engine number 1040 of this type appeared as part of the Walton Collection when that wonderful assemblage was auctioned off. The only other Special Series II of our present acquaintance forms part of Alan Strutt’s collection. This latter unit is equipped with the optional Nordec flywheel and clutch for car use, and bears the serial number 1126.

This relatively small sample does not decisively settle the question of whether or not the glow and spark models each had their own consecutive serial numbering system or if they were simply numbered sequentially as they came off the line, regardless of type. Only the finding of two engines of different types bearing the same numbers would confirm the former system, and I must confess to a strong feeling at this point in time that the latter system in fact prevailed. It would have the considerable advantage of avoiding the duplication of serial numbers on two engines (one glow and one spark) which would inevitably result from the maintenance of parallel numbering sequences without the use of a letter prefix.

If the parallel numbering system had been adopted, one would logically expect to find a prefix in front of the numbers to designate which of two engines having the same number was the glow and which was the sparker. As it is, I suspect that the engines were sequentially numbered regardless of type and their ignition system was recorded in the factory ledger for reference in the event of a servicing requirement. Quite likely it was the state of the order book that determined the relative production of the two variants in any given batch. The selection of the ignition system could easily be made at the final assembly stage on the basis of the order book without upsetting production - all that was required was to fit the appropriate front end to the rest of the engine.

A further factor which suggests that the engines were numbered consecutively regardless of ignition type is the fact that the spark ignition version is considerably less commonly encountered today than the glow model. Even so, the highest recorded serial number for an original Series I sparker is 870 while the Series I glow models only go up to number 827. If there were two parallel numbering sequences, this would imply if anything that the sparkers outnumbered the glow versions. In fact, the relative scarcity of surviving spark ignition models suggests that this was not the case. The observed data are most readily explained by the notion of a single numbering sequence covering both types, with the majority being glow-plug models.

The above-referenced number is not the only mark on the engines. Both of my examples also have a letter "T" stamped into the top of the left-hand mounting lug. I would assume that this most probably confirmed that the engine in question had been tested at the works. The instruction leaflet claimed that all engines were tested prior to despatch, and this may well be the meaning of this particular mark.

So how many were made? Impossible to say, but present indications based on known serial numbers are that between 1100 and 1200 engines of all types were produced in total over the two years or so during which production continued. Of these, it appears unlikely that more than 300 or so were of the "Special" variety. If more data become available in the future, it may be possible to revise these figures somewhat, but they are unlikely to be far out. Whatever the number, it's clear that sales cannot have been all that brisk or production would likely have continued.

Conclusion

The fact that the engines were extremely well-built and consequently very durable as well as being rather too large to simply "lose", allied to the fact that there was relatively little scope or incentive for their use after the early 1950's, has ensured that a significant proportion of the engines which were produced have survived to the present day. They are still encountered from time to time on offer from dealers, at swap meets and on eBay, changing hands for respectable but as-yet by no means outlandish prices. Being racing engines, many of them were modified in various ways, and hence the main challenge today is to find one that remains in more-or-less stock condition (I've been lucky!)

The two versions of the Nordec Special appear to have been produced in very limited quantities indeed by comparison with the earlier R10 and RG10 models. Consequently, the vast majority of Nordec motors which do turn up are the R10 and RG10 models described above in detail—examples of the Special series are very rare indeed. We were unable to find an example to photograph for this article!

Anyway, there we are—a brave and quite worthy British attempt to take on the McCoy and its relatives in the racing engine field, and one which was both very well-made and at the end was actually approaching a comparable level of performance to its American rivals. It is sad to reflect that the Nordec disappeared just when it had finally been developed into a truly competitive engine. It was a combination of time and place rather than any major deficiencies in the design, especially in its fully-developed form, that killed the Nordec series. On their intrinsic merits, these engines undoubtedly deserve our favourable remembrance!