During the installation lap round the parking lot the other day, the engine was reluctant to return to idle. The most likely cause being the aggressive curve of the Bosch 041 dizzy and sticking advance weights from it having sat unused for years. Rather than go through the dizzy to sort it, a Marelli S103BA from an early 1970s Spica car would take it's place. This Marelli, despite it's application, has a surprisingly good advance curve.
The change-out went as smooth as could be. Note that the o-ring is in the timing cover prior to installing the dizzy. This is mandatory because if the o-ring is installed on the dizzy, the ring will expand so as to prevent the dizzy from fully seating.
The static timing was setup using an ohm meter. First, the fixed timing mark on the crank pulley was lined up (the 'F' mark on the pulley) by turning the engine in the normal direction of rotation. An ohmeter is then hooked up to measure the continuity (or resistance) between the movable and fixed points in the distributor. A reading of zero indicates the points are closed (current is flowing to 'charge' the ignition coil). Then advance the timing by turning the dizzy counter-clockwise until the points just open (when the ohmeter reading changes from zero resistance to infinity). At this point (pun), the current flowing through the ignition coil primary stops, the coil magnetic field collapses which induces high voltage from the coil secondary to fire the sparkplug.
Series 2 USA 1750 GTV (in Series 1 European clothing)