If the ignition timing is correctly indexed but the engine still fails to 'take revs' under load, the mechanical advance mechanism within the distributor may be seized. The Alfa Romeo Nord engine relies on internal centrifugal weights and springs to advance the ignition timing as engine speed increases. Over time, old grease can harden or corrosion can occur, locking these weights in the fully retarded position.
This failure prevents the timing from advancing from the static 'F' mark to the required total advance at higher RPMs. Consequently, the engine will idle acceptably but will suffer from severe 'bogging' or hesitation when the throttle is opened, as the combustion event occurs too late to generate power at higher engine speeds.
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