Last genuine Rover 1275cc new crankshaft with 1.75" big ends -this was tuftrided for use in turbos.Forging number CAM6581.A-series crankshafts are most definitely forged. But also cast. The
final shape is forged out of a cast billet. Pre A-plus cranks were
manufactured in a different way to the A-plus ones, but the end result
is a component with the same mechanical properties but very slightly
different chemical properties. Pre A-plus cranks went through three heat
processes - first heated to red hot to forge the shape, second to harden
it and third to temper it. A-plus cranks were heated just the once to
forge it, then left to air cool in a controlled environment. The latter
was done for no other reason than to cut the costs of manufacture.
Despite this it was most definitely more than up to the job, witness
it's use in the Metro Turbo engine, albeit in Tuftrided guise to
increase it's fatigue and wear resilience, and used in many a high
performance and full race engine.'