Stage II performance engines are built to order for both the 1275cc A-Series and the 1500cc engine, combining targeted improvements to the cylinder head, camshaft, and rotating assembly to deliver a meaningful increase in power and torque while retaining the engine's fundamental reliability for road use. Like all reconditioned engines, performance units are built to Federation of Engine Remanufacturers standards and carry a 12-month unlimited-mileage warranty, available on the same exchange and surcharge basis as standard reconditioned engines with the same delivery, collection, and return processes, and a typical build time of three to four weeks once the order is confirmed. Performance engine builds can be tailored to suit the intended use, whether fast road, sprint, or hillclimb, so discussing specific requirements before ordering is recommended as the camshaft profile, compression ratio, and head work can all be adjusted to suit the application.
Stage II Cylinder Head
The Stage II specification includes a gas-flowed and ported cylinder head with enlarged and polished inlet and exhaust ports, reshaped combustion chambers for improved gas flow, and larger valve seats, with hardened exhaust valve seat inserts for unleaded compatibility. A reprofiled camshaft with a more aggressive lobe profile increases both valve lift and duration, working with uprated valve springs to control the faster valve opening and closing events. The head work is where the majority of the performance gain is achieved, improving the engine's ability to breathe efficiently at higher engine speeds, and the head is assembled with new valves, uprated valve springs, and bronze valve guides throughout. A fast-road specification prioritises a broad torque curve and good low-speed response for everyday usability, while a competition specification can sacrifice some low-speed tractability for higher peak power, the camshaft selection being the principal lever in setting the engine's character.
Balanced Bottom End
The bottom end of a Stage II engine receives the same comprehensive rebuild as the standard reconditioned unit, a rebored block, reground crankshaft, and new bearings throughout, but with the addition of careful balancing of all reciprocating components. The pistons, connecting rods, and crankshaft are weight-matched to minimise the vibration that unbalanced components produce at higher engine speeds, allowing the engine to rev more freely and reducing the mechanical stress on the bearings and block at the sustained higher speeds a performance engine will regularly see. The compression ratio is set during the build to suit the intended fuel quality, higher compression delivering more power but requiring higher-octane fuel, and on the 1275cc A-Series the balancing work is particularly worthwhile given the engine's willingness to rev.
Clutch, Ancillaries & Running-In
Stage II performance engines include the supply and fitment of a clutch, included in the performance engine specification unlike standard reconditioned engines where clutch supply and fitment is an additional charge, and the engine is supplied as a long engine with ancillaries such as carburettors, manifolds, starter motor, dynamo or alternator, water pump, distributor, and external fittings transferred from the outgoing engine. A Stage II engine requires the same careful running-in as a standard reconditioned unit, approximately 500 miles at varied engine speeds avoiding sustained high revs or heavy loads, with the oil and filter changed at 500 miles. The cooling system must be filled with a conventional antifreeze mix or recommended coolant, as waterless coolant must not be used since it may lead to premature engine failure and will void the engine warranty, and a fast-road or competition engine generating more heat than standard benefits from attention to the cooling system, an aluminium radiator or electric fan being worthwhile additions. The carburation and exhaust should be matched to the engine specification, the larger SU carburettors and a free-flow exhaust complementing the improved breathing, and a rolling-road setup after running-in optimises the fuelling and timing for the specific build.