E-series engine
Designed and specially built to become the Corporation's new mid-sized engine, the E-Series had a troubled early life, but eventually matured into something very worthwhile indeed.
New engine, new factory; new start?
By the mid-1960s, it had become clear to BMC's management, that in order to maintain sales volumes, the company would have to produce a new mid-sized car to replace the Farina saloons. The plan for the BMC 1800 to do this had gone by the wayside in light of it's increased girth, price and ambition, meaning that the older car would have to soldier on for some time longer...
As it was, the new mid-sized car (the ADO14), which began to emerge from BMC during 1965/66, was an interesting design, which Sir Alec Issigonis planned to be a technological leader in its field. Reflecting BMC's confidence at the time, this plan called for an all-new body, and an all-new engine. Initial thoughts were that the new engine (codenamed the ADO32) should be light and compact, and displace about 1300cc. Issigonis was sold on the idea that upward expansion of his engine should be achieved by the addition of two extra cylinders (a principle he also explored on the DX engine used in the gorgeous 9X), which meant that there would be little need for expansion through boring/stroking, and that meant that in search of compactness, ADO32 could get away with siamesed cylinder bores.
At the original displacement of 1300cc, the six-cylinder version of the engine (codenamed the ADO25) would displace almost 2-litres; a size that would pitch it perfectly within the executive market, alongside Rover and Triumph's less sophisticated offerings. It was noted by Jeff Daniels in his book, "BL: The Truth About The Cars", that this plan was soon pulled apart by two factors:
1) The A-Series was being developed into a very useable 1300cc engine, and although in 1966, it was still considered an exotic unit for use in the Mini-Cooper, productionized versions were on their way.
2) The accountants dictated using ADO17 doors, which set the ADO14's practical wheelbase at just under 105-inches at the very least. Far too big for a 1300cc engine.
These factors meant that ADO32 would need to be expanded to 1.5-litres, and in turn, ADO25, 2.2-litres.
As Longbridge and Cowley were at capacity churning out A-Series engines for the ultra-successful Mini and 1100, a new factory would need to be built to produce the new engines; especially at the volumes that BMC anticipated for it! The site chosen was Cofton Hackett, and it went up during 1967 and 1968.
Sadly, the new engines (christened E- and E6-Series) were launched after Leyland's takeover of BMC, and because of the ADO14's (Maxi's) less-than-sparkling performance, it was soon decided by the new management, that the E-Series would need to be enlarged, in order to develop more torque and power. According to Daniels, Harry Webster had his work cut-out extending the E-Series unit, but finally managed it by stroking it just enough as not to foul the transmission-in-sump gearbox internals. The fact that it moved it extremely close to the 1800cc B-Series engine, was purely incidental...
The larger version of the four-cylinder E-Series engine duly appeared in 1970 (eighteen months after the launch of the original Maxi), and it silenced many criticisms of the 1968 Maxi. In HL form, it produced 72bhp, but this was upped later, when a twin-carburettor version putting out 91bhp was added.
What about ADO25 - the E6 engine? That first appeared in the 1970 Austin Kimberly/Tasman, then the domestic ADO17 two years later. Blessed with exceptional smoothness, it received a warm welcome on the marketplace, but was a little overshadowed by the age of the car it was in (the ADO17 was eight years old at this point). The E6-Series engine, rather oddly, displaced 2227cc (which based it on the 1485cc version of the four-cylinder E-Series engine), and it did make commentators wonder about whether a suitable 2.6-litre version could be produced.
Along with the Maxi, the E-Series engine found its way into the Allegro in 1973 and the E6-Series, into the Princess in 1975... and that was about it. All European installations were transverse front wheel drive, but Leyland Australia saw an advantage in using it in the Marina (longitudinal, rear wheel drive) and P76...
The E- in Australia
By Merv Sheather
In Australia, the E-Series first came to light as the means to upgrade the ADO16's power and torque. Fraught with inherited engineering problems, launch, the Morris 1500 had problems several technical gremlins (cable backlash, no detent plungers, third motion shaft circlip detachments, due to designed selective fit 'v'' groove retention circlip).
The 1500 was a sales disaster, due to widespread press reports of these gearbox failures, and it forced the Australian subsidiary to accelerate the introduction of the Marina.
The Marina was released with the E-Series engine in 1500 and 1750 4-cylinder forms, as well as a 2622cc 6-cylinder version, conceived to compete with local market cars from GM Holden, Chrysler and Japanese imports.
The E-series did not have a considerable power output gain when it jumped from 1500 to 1750cc. To overcome the advice from the Marketing Section (about the small hike in power compared with the 1500), the Engineering Section down-rated the output of 1500cc version by adding a pressed metal choke sleeve in the induction manifold below the carburettor (Thus the 'detune' modification of a manifold choke. This really was a 'desperate act ' by Engineering Department to comply with Sales Department's requests).
The 1750cc was seen a 'market adequate' by the Sales Deptartment (when compared with the main competitors' engines). The main problem was the 1500cc in the Morris 1500-standard tune was far too close to the developed bhp of 1750cc. As the Marketing Department stated at board level, "the buyers only read engine output, eg , bhp figures and very rarely consider the torque at rpm figure". A smaller 1 1/2-inch SU carburettor was used rather than the 1 3/4 inch SU carburettor as was used on the Morris 1500. Many owners became aware of the simple modification to obtain increased power, and removed this pressed in metal sleeve.
The model range had moderate sales success until the Zetland/Waterloo Pant closure which occured in November 1974.
Utilised also in South Africa from CKD kits supplied by Leyland Australia for both Marina and P76 vehicles. E-series 6 cylinder used in South African for locally assembled P76 cars had a 2 inch SU to give higher top end performance gain.
Note: South African Rover SD1s used the E6-Series engine in 2622cc form, and it compared very favourably with the domestic Triumph-derived Rover 2600
The E's fate...
So, did the E-Series see out its days in the Maxi and Allegro, and the E6- in the Princess?
Sadly, the E6 died with the Princess in 1982, but the four-cylinder version continued...
One thing that the E-Series proved in the end, was that it was long-lived. During the late 1970s, it was developed for use in the LC10/LM10 (after dropping the O-Series) in conjunction with an end-on Volkswagen gearbox. Interestingly, the LC10/LM10 version, dubbed the R-Series was produced in 1598cc form (half way between the E's 1485cc and 1748cc), and according to contemporary Austin-Rover technical briefings, this proved to be the perfect size for the unit, using existing valves.
The R-Series was a stepping stone, though; an anomaly that lasted eighteen months (for political reasons), until the S-Series engine appeared in 1984. And the S-Series? This was an extensively revised version of the R-Series engine. This unit lasted until 1993. Product plans from the early 1980s spoke of a diesel version of the S-Series engine, for use in the stillborn Austin-Rover AR6... I have yet to uncover any evidence to suggest this engine ever left the drawing board.
Copyright © 2002-2003 Keith Adams
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