"The A-Series may have been almost immortal by the early 1970s, but it did not stop BL developing alternatives. Here we describe the H and K-Series prototypes that were designed for the ill-fated ADO74 supermini.
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.
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."
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