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 its 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, 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 in Birmingham, 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 cutout 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 Australian 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...
When the 18-22 was under development it was envisaged that the new car should make use of BL’s most recent engine range, the E-Series. The 6-cylinder unit would be carried over from the old ADO17 Austin 2200, whilst the 1800 B-Series would make way for the 1750 4-cylinder unit. The problem with that was that BL’s engine manufacturing plant, Cofton Hackett, was already at full capacity supplying E-Series 1500 and 1750 engines for the Maxi and Allegro, and it would also have meant that the lesser powered cars would receive the 5–speed gearbox whilst the 2200 struggled on with the four speed ‘box.
Neither the 1800 nor 2200 were particularly exciting units; both had quite respectable torque outputs and the 2200 six was turbine smooth, they also returned good fuel economy for cars of their size, but they were endowed with less than sparkling performance. Another glaring omission was a 5-speed gearbox, though the 4-speed ratios were quite well chosen the fact remained that the lesser E-Series engined Allegro and Maxi came with a 5-speeder. And when fitted with the three-speed Borg-Warner automatic the performance became even more leisurely.
Because of the need to fit the 2200 engine in the ADO71, the styling of the front of the Wedge had to be compromised to accommodate it. The 2200s were fitted with twin SU HIF6 carburettors to feed the six hungry pots. Performance was rather leisurely but the super smooth unit made up for this. Output was 110 bhp @ 5250 rpm and torque: 125lb ft @ 3500 rpm. As with the 4-cylinder, there is a lot of room around the engine.
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.
Copyright © 2007. Keith Adams
Certain paragraphs added by Kevin Davis.
Updated 7th May 2007.
It was long and it was tall, but it still couldn’t fill the Princesses huge engine bay.