Progression jet

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Keith Clements
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Progression jet

Post by Keith Clements »

From tech notes part 18.
It has been found that with high mileage carburettors which are in otherwise sound condition, i.e. negligible wear at the throttle spindle, good gaskets, not flooding etc., that the car has a tendency to snatchy running or hesitation when moving away from rest. This is a rich phase which appears to be caused by wear (or indiscriminate probing with wire of the very fine hole at Item 22.
A dramatic improvement was found to be achieved by replacing progression jet, Item 24, with a smaller one. If no smaller jet is available try filling the original hole with solder or 'Easyfile) and redrilling with a 1 mm drill. This gives a jet orifice of 0.040" as compared with genuine jets – Number 110 1.15 mm (0.045"), Number 120 1.19 mm (0. 047").


Now I have had no success in removing said progression jet, even by heating the body of the carb or soaking in diesel. Any ideas?
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