Carole Nash Classic Insurance Specialists

Engines : H and K-Series prototypes

The A-Series may have been almost immortal by the early 1970s, but it did not stop the company developing alternatives.

Here we describe the H and K-Series engines that were designed for the ill-fated ADO74.

Transmission-in-sump could have had a future

Left: H-Series engine. Right: K-Series engine.

Left: H-Series engine Right: K-Series engine

Any AROnline readers who have read the Metro development story might recall that, back in the mid-1970s, the decision was made to build a car around a developed version of the A-Series engine and transmission, instead of designing a new power unit – both the 9X and ADO74 had been destined to have an all-new engine. Eminent Engineer Roy Brocklehurst described how the company were, ‘tickled pink with its NVH performance’ once the upgrades had been made which turned it into the A-Plus.

However, what about the engine that had been passed over when the ADO74 was scrapped? Obviously, at the time of the Metro launch in 1980, the company’s Directors tended to describe the K-Series engine as not being a great enough step over the A-Series to justify the cost (and, in essence, they were correct to do so, as Bill Appleby and his team knew what they were doing when they designed the A-Series), but that is to undermine what Austin-Morris engineers achieved with the H and K-Series engines.

In 1972, when the ADO74 programme began, the engine which was then intended to be used was called the H-Series and that employed the transmission-in-sump layout. As the ADO74 was initially devised as a straight replacement for the Mini, the capacity was limited to a maximum of 1000cc – an extrememly compact unit, it featured Siamesed bores (just like the E-Series engine) and an ohc cylinder head with bucket tappets. The distributor was mounted directly on the end of the belt-driven camshaft and the water pump and alternator were driven from the crankshaft. The oil-pump was also crankshaft mounted. A two-shaft transmission layout was designed, and this was driven by helical spur gearing, which was carried in a housing integral with the rear transverse face of the cylinder block. The clutch was of conventional design, and this had a separate cover.

The integrated engine/gearbox was designed for ease of servicing, and access was achieved by removing the single sump – the clutch was also similarly easily accessible through its cover. In one fell swoop, this clever design overcame the criticism of the A, B and E-Series engines that they were difficult to service. This design also did not sacrifice the undeniable packaging advantage of the transmission-in-sump system.

In total, four H-Series prototypes were built and were run for 200 hours on the test bed and 25,000 miles on the road.

The H evolved into the K-Series engine, when the ADO74 grew, and the limitations of the 1000cc upper limit became too much for the larger car. In essence, the K-Series differed from the H in three areas: the capacity was now 1300cc, the gearbox featured five ratios and the block was inclined steeply to the rear to improve packaging.

The new two-shaft, five-speed gearbox was carried in a hefty housing, cast integrally with the rear face of the cylinder block (see diagram above) and, like its predecessor, the engine and gearbox were closed off underneath with a single pressed steel oil pan. As before, servicing was made relatively easy by this layout – since the gearbox internals and crankshaft could be released by the removal of simple half-bearing caps.

Five prototypes were built and run on the road in ADO16 mules and completed 800 hours on the test bench, but the project was part of the ADO74, and so was shelved when the new supermini was canned in 1973. Would the story of the Metro have been any different with this engine in place? Probably not, as the car was a success, and a long-lived one at that…

Keith Adams

Keith Adams

Editor and creator AROnline at AROnline
Created in 2001 and built it to become the world's foremost reference source for all things BMC, Leyland and Rover Group, before renaming it AROnline in 2007.

Is the Editor of the Parkers website and price guide, formerly editor of Classic Car Weekly, and launch editor/creator of Modern Clsssics magazine. Has contributed to various motoring titles including Octane, Practical Classics, Evo, Honest John, CAR magazine, Autocar, Pistonheads, Diesel Car, Practical Performance Car, Performance French Car, Car Mechanics, Jaguar World Monthly, MG Enthusiast, Modern MINI, Practical Classics, Fifth Gear Website, Radio 4, and the the Motoring Independent...

Likes 'conditionally challenged' motors and taking them on unfeasable adventures all across Europe.
Keith Adams
Posted in: Engines

17 Comments on "Engines : H and K-Series prototypes"

Trackback | Comments RSS Feed

  1. Paul says:

    I dare say the A+ did perform well. But the Metro/Maestro where being launched just as Ford and GM/Vauxhall where ditching their Iron headed push rod lumps for the CVH and Family 1/2 respectively. Alloy heads, Overhead Cams, hydraulic tappets and power outputs for the standard engines that exceeded those for their predecessor “GT” versions. Slotting a 30 year old pushrod Engine into ARG’s new cars sent out all the wrong messages.

    • Boo says:

      It never did the Renault 5 any harm using an old pushrod design. Theirs was alloy-headed and 5-bearing but a similar lifespan to the A Series.

      • Boo says:

        I meant to specify the 1984 Super 5 there (being a similar ‘new car, old engine’ to the Metro), not the original 5.

  2. drae says:

    the metro and maestro still had problems with the transmission of one sort or another.

    Could the A+ not have use the gearbox and configuration shown above, (or the E series in the case of the maestro).

    It could have saved AR money wasted importing VAG units and looks like it could also have had positive benifits in terms of packaging and weight distribution.

    I know both metro and maesto handled well, but both could have benifited.

    • Drae,

      Better late than never…

      The E-Series transmission with its remote cable-operated gear-shift was berated by the press from its launch for indistinct changes that felt like pushing the gear stick through a box of loose ball-bearings. Remember that at that time, the mass-produced Ford gearbox fitted to the Escort, Cortina etc was absolutely superb; slick, short movements and strong with large synchromesh hubs. It was used by many track racing cars. A brilliant gearbox design.

      No, no no. The E-Series box was a gonner for that reason alone.

      Then there was the crippling effect of designing an engine around an alien component. The H and K-Series engines were crippled enough by board members who specified its minutiae even before a designer had sharpened his first pencil.

      We engine designers at that time worked literally arm in arm with our colleague transmission designers who were all extremely proficient. The problem for both teams (about 25 designers in each team) was a company ham-strung for cash and a management team who were way out of their depth.

      • Nate says:

        Ray Battersby

        Given your involvement as a designer of the H/K-Series engine, was wondering whether you can clarify some things regarding this project?

        Did the H/K-Series share anything with the A-Series as one or two books have suggested a connection with the A-OHC?

        How did the H/K-Series compare with the A-Plus and A-OHC (assuming the latter is completely unconnected with the H/K unit)?

        What was the minimum capacity of the H/K-Series units and had the project been given the green light, how much further could the later K-Series engine capacity have been increased by beyond 1300cc upper limit?

        Thanks in advance

  3. Harry Webster was the Engineering dictator and control freak of all we did in the engineering block. His deputy, Ray Bates was a poodle by comparison (though he had much bigger feet).

    Regarding the capacity of the H/K-Series engines they were chronologically (from memory):

    H-SERIES – 1000cc ‘dedicated’ engine. In his single-sided, single sheet document ‘DESIGN CONSIDERATIONS FOR NEW 1000 CC UNIT’ dated 24 Sep 1970, Harry Webster stipulated…

    1. Fully siamesed bores

    7. 3 Main Bearing Crankshaft*

    17. Cylinder bridge width 7/32″ **

    21. Crankcase to have approx. 1/8″ clearance for conn rod path.

    * See later
    ** 0.218″/5.5mm

    Collectively, these strictures were designed to prevent any future boring and stroking of the cylinder block. The very narrow cylinder bridge width would also cause much anguish by Coopers and Klingers who were each tasked with producing a cylinder head gasket design able to withstand the heat, the fretting and general hostility in this bridge area without leaking between adjacent cylinders.

    Two further designers joined the team between January and March 1971. The first H-Series engine ran on schedule on the test bed in December 1971.

    K-SERIES 900/1100 – Despite Webster’s steely determination to have a ‘dedicated’, ham-strung 1000cc engine, early in 1972, he decided to hedge his bets. He now wanted it to be a dual-capacity design encompassing 900 and 1100ccs.

    This 900/1100 engine became the basis for the K-Series whose entire power unit – like the H-Series – was canted back on installation. However, its cylinder bank was also canted back relative to the sump joint-face. Its doubly laid back cylinders allowed the unit to fit beneath the very low bonnet-line of ADO74.

    K-SERIES 1100/1300 – But…but something had clearly given Harry Webster the jitters because no sooner had we started designing the K-Series 900/1100 than he issued another edict, changing the capacity range yet again. This led to the birth of the K-Series 1100/1300ccs project. Due to the continuing stipulation in Webster’s ‘Design Considerations’, neither the bore nor the stroke of the K-Series 1300cc engine could be increased.

    But it didn’t matter anyway. The entire ADO74 project was dropped including work on its engine. I believe that within this ‘family’ of engines (H-1000, K-900/1100, K-1100/1300) only the H-Series was ever built and only the H-Series was ever run on a test-bed and fitted to a vehicle for road testing. I seem to recall that many of the K-1100/1300 parts were manufactured but not assembled by the time the project was scrapped in 1974.

    The legacy of these engines was their inspiration within the design of the A-Series OHC and O-Series OHC engines, whose cylinder heads and valve-gear bear the hallmarks of their ancestry.

    In his excellent book ‘The A-Series Engine’, Graham Robson says that the H-Series ran for 200 hours on the test bed and completed 25,000 miles on the road. Actually one engine, after running in, was subjected to a ‘400 hour Endurance Test’ which started on 11 Jan 1972 and was completed on 11 Feb 1972. This gruelling test was the equivalent of running on the road for 26,000 miles with the engine running at full throttle and full load for over half of the time. The full test comprised of 69 cycles (each of 5 hours 50 minutes duration). During each of these cycles the engine speed and load was varied as follows:

    1000 None 10 mins
    6250 Full 10 mins
    4500 ½ 10 mins
    4800 ⅓ 60 mins
    2400 Full 60 mins
    2400 ¼ 10 mins
    5400 Full 60 mins
    4500 ¼ 10 mins
    6000 Full 60 mins
    6000 ¼ 60 mins

    A-SERIES CARRY-OVER PARTS (Ignoring fasteners)
    Oil filler cap
    Mainshaft Bearing Caps and Screws
    Water pump bearing and seal

  4. Kevin Steele says:

    This basic essence of this design of course DID make it into production – as the Peugeot/Citroen “suitcase” engine – as found in the 104/Citroen LN/Talbot Samba and the early 205s. Almost identical in fact, with the engine canted so far back at an angle, and the gearbox sort of on the side. Proof that in Britain we’re good at coming up with the initial idea, but lousy at following it through.

  5. Susan Young says:

    I felt the A-Plus did a good job in the Maestro, let down by the gearbox and in one model silly ratio’s for economy. If my memory serves me correctly wasn’t the E-series designed to be 1300cc?

    • Kevin Steele says:

      Think it may have been, but obviously 1.5 was as small as it ever got. I think there has been few cases where manufacturers have succeeded in building a truly “scalable” engine that can be both very small and very large. Trouble is at lower cubic capacities, you still have a big heavy engine displacing a small capacity so they end up offering little or no economy advantage over an engine that’s designed to be small in the first place. Ford for instance tried it twice and failed….

      – Ford CVH; designed to go as low as 1.1 litres but this capacity was dropped when they found out that it wasn’t any more economical than the old 1.1 Kent/Valencia engine yet was more expensive to build.

      – Ford Zeta/Zetec – again it was designed to be as small as 1.4 litres, but never got this low.

      But in essence most European manufacturers of that era seemed to use two engine families in a ‘small’ and a a ‘large’ format to cover the entire 1.0-2.0 size range – some examples:

      Peugeot-Citroen = TU (1.0-1.4 litres) XU (1.6-2.0 litres)
      GM/Opel-Vauxhall = Family I (1.2-1.4 litres) Family II (1.6-2.0 litre)
      VW/Audi = EA111 (0.9-1.4 litres); EA127 (1.5-2.0 litres)
      Renault = C-type/E-type (0.8-1.4 litres) F-Type (1.7-2.0 litres)

      sure people can think of some more!

      • Nate says:

        Interesting, do any specs exist on the unproduced 1.4 Ford Zeta engine? Would have certainly been an improvement over the 1.4 Ford CVH.

      • Greg says:

        Remember the old Alfa DOHC four from the Sixties?
        Originally designed as a 1.6 it was downsized to a 1.3 which was never as lively or well loved as its predecessor that was designed as a truly phenomenal 1.3.
        Later it was bored and stroked to 1.75 which was a very racy engine with some durability and reliablity problems. Taking strange measures like asymmetrical conrods to move cylinder bores further apart it was increased to 2.0 which was the least pleasing iteration, unwilling to rev and with NVH problems when compared to its smaller siblings.

      • Sam Eyers says:

        The smallest Ecoboost engine is 1 litre, the largest is about 4.6 litres (in the new Mustang). Are they basically the same engine scaled up/down or different designs under the same name?

  6. Tony Evans says:

    I was never a fan of the engine and the gearbox sharing their oil. The two require different lubrication properties. Probably why no-one does it today.

    Strikes me that Harry Webster was a bit of a ditherer. As any engineer will tell you, there is nothing worse than moving the goal posts half way through a project for increasing the cost.

    I have nothing against the A series which was a reliable and economical unit, but it was always handicapped by the 5 port cylinder head.

  7. russell pigott says:

    When was the A series OHC built? About 25 years ago I bought an O series 16v twin cam which I ran in an MG Maestro, the chap I bought it from not only had a few of these but also quite a few A series OHC engines. Were these originally intended for the metro?

  8. Alasdair Mackenzie says:

    @Kevin Steele.

    The Peugeot engine laid flat was a fantastic pice of packaging, but it was a pain to work on.My brother’s 104 was pretty long in the tooth by the time we had it so had it’s issues. We became well versed with it while he had it, but it lasted longer than the rotbox Metro he replaced it with.

    Minor services were easy enough, but anything major was an engine out. With one working on top and one below,we could have the entire engine and gearbox sitting in front of the car in 40 minutes using just our basic facilities at the roadside.

    As was the case with a lot of French cars of the time, the spare wheel sat on top of the engine was well. That couldn’t have done the rubber any good!

    • Richard16378 says:

      I did wonder how well Peugeot sorted the oil flow in the suitcase engines.

      In F1 BMW canted over their turbo engine for the Brabham BT55 & it had all sorts of problems with the oil flow being disrupted.

Have your say...