hi lawrence, k just focusing on the engine side
Intake:
Teflon insulating inlet manifold spacer: prevents engine block heating the manifold, keeps the air cooler till it enters the inlet port.
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-50#post-510149
CAI box: shield the carbs from engine heat and supply with air from a cold high pressure region.
Compression:
if the head & block is skimmed alot from original thickness, it will retard timings of both inlet & exhaust cams. best to precisely check and adjust the cam timing to match factory cam timing and tune em from there.
Combustion
clean white oxide off the dizzy cap points if fitted
check spark gap
orientate spark gap towards inlet port
Exhaust
smooth out the ports
match head ports to gaskets & inlet/exhaust manifolds
Weight
lighten flywheel
balance crank assembly
knife edge crank counterweights
Oil control
windage tray: prevent oil sloshing/foaming against the spinning crank during rapid cornering.
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-66#post-536819
trap door pickup: keep the pickup surrounded by a valved tank of oil at all times to prevent oil starving during high g-force.
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-63#post-530476
dual catch can: reduce amount of oil vapours recirculating back into the inlet manifold, keeps the system cleaner with less oil contamination.
reliability depends on many factors including:
condition of all bearings, seals, rings, fuel quality, service intervals,
aggressiveness & accuracy or combustion afr mixture & timing,
driving load & distance, mostly urban driving or mostly WOT racing?
