You should also understand a few facts about FULVIA carbs in particular. Often carbs are blamed for misfiring and malfunctions which have a different origin. Before tuning the carbs you must be sure that the ignition, the valve timing and the fuel delivery are perfect. Other culprits can be the servo vacuum hose and the various gaskets between carbs and rubber mounts, air filter box, etc. The rubber mount must be perfect, without any cracks.

Screw adjustments on the four carbs will only correct the idling, NOT what happens when you push the throttle open! Flooding and wrong performance at speed suggest that the float level is wrong, that the needle valve small gasket is too squeezed or that the accelerator pump diaphragm is malfunctioning. The latter can be due to a tear in the diaphragm or to build-up of dirt (often quite amazing) in the diaphragm chamber. A common problem is also that during the years various people have changed the jets putting others of the wrong size in the pathetic hope to improve performance and/or fuel economy. This never produces good results. Finally, it is absolutely essential to balance the two twin carbs PERFECTLY with a suitable tool (as explained in carburetor tuning) because even a slight mis-alignment will be felt by the car. NEVER overtighten the four idling adjusting screws as their seats are fragile and easily damaged with the results that you have an air leak requiring a NEW (and expensive) carb.

Don't try tuning unless you know what you are doing.
- Andrea -