Less flex, vibe and harmonics issues at all rpm ranges
A series are well built but this insures that your pricey
worked engine can go for longer periods without rebuilds,
leaks, lose font pulleys, head gaskets or flywheels.
These billet cranks also have extra flywheel bolts also.
This is specially noticeable in similar Ford Kent engines
when they are fitted with modded FCW L series cranks to
save money over cosworth billets, owners of Kent engines
notice improved harmonics, smoothness and less leaking.

Im actually a big fan of the Kent series, its casting is
lesser quality than the A series but with some aftermarket
parts and massaging they are also nice units that can be
cheaper in the end when modifying them for 2000cc when
using the L series crank conversion on the later blocks.

hows that a Ford engine improved using a Nisan crank :))

Kents use Heron CCs more suitable for grunters than for
all out hp unlike the A series which is although not in
the crossflow latyout it still works best with kidney CCs
whereas crossflows benefit different chambers.