2.0-litre engine

THE 2.0-litre engine is a good replacement in the absence of the original 1.6-litre unit because it looks similar and the extra capacity provides significantly more low-down torque. The extra cc was achieved by boring out the cylinders from 69.5 mm to 77.8 mm diameter – a modification that required a new block casting which is wider at the top, leaving more space for the cylinder cooling jackets. Both engines are of the so-called Siamese bore type, which had no coolant space between adjacent cylinders. Later, in 1953 the more familiar spread bore engine was introduced having space for a cooling jacket around each cylinder.

This vehicle’s original 1600cc engine and the current 2000cc unit are both derived from the Rover car IOE (inlet over exhaust valve arrangement) engine. The IOE engines in the Series I were relatively sophisticated for their type, having a combustion chamber design that was not only efficient but, along with the valve arrangement, allowed the engine to run satisfactorily on poor quality fuel – a factor that helped the Series I’s worldwide sales success.

The IOE engine’s inlet valves are in the top of the cylinder head (as with the overhead valve configuration of the later Series I diesel and Series II/III petrol and diesels), but the side exhaust valves are inverted in recessed combustion chambers at the top of the bore in the cylinder block. The exhaust valve stems protrude downwards inside the block where they are worked by the camshaft below them, via rockers with pads (later rollers). The inlet valves are operated by more conventionally positioned rocker arms on the top of the head, moved by pushrods which are driven via another set of rockers down at the camshaft.

We’ll see all of this as we take a close look at the now dismantled engine and some of its new and restored parts over the next few pages.