F. Testing Petrol Supply between Float Chamber and Cylinders

7. Is the wing nut Q, holding the float chamber to mixing chamber, properly screwed up? If this nut is slack, sufficient air may leak through the joint to stop the engine when running slow, although it may have been running well at high speeds.
8. Also examine for tightness the nuts attaching the induction pipe to the cylinders, to be sure there is no air leakage at the flanges. If there is no air leakage, the fault lies between the float chamber and mixing chamber.
9. Does the petrol regulator spindle R follow the movement of the economy lever control S?

(a) No. Turn spindle to make it move freely.

(b) Yes. The fault is either -

(i) An obstruction in the passage to the jets Y. Turn off tap C at the autovac (see page 38), Disconnect union T at the carburettor. Remove wing nut Q and lower float chamber and jets away from carburettor body. Remove lid U and float V. Remove regulator spindle R and its spring by unscrewing plug W. Thoroughly wash out the float chamber and passages with petrol.

N.B. When re-assembling be sure to replace spring properly before inserting regulator spindle R in its hole. Screw the plug W well home

(ii) An obstruction in one or more jets. Remove one jet with a proper jet spanner; probe it carefully from below with a fine needle and blow through it. Replace this jet at once to avoid confusion, and then proceed similarly with the other jets, one at a time.

(iii) Sticking of the carburettor sleeve B. This very unlikely occurrence would be symptomised by unsatisfactory running over a portion only of the speed range, Should suspicion attach to the carburettor sleeve, immediate communication should be made with the Company or one of its Service Depots. Inexpert removal of this sleeve, or attempts to polish it with any abrasive, may lead to permanent derangement of the functioning of the carburettor.