I) THE FUEL SYSTEM time it will be advisable to clean out the entire fuel feed system as this trouble is caused by foreign matter in the fuel, and unless this is removed it is likely to recur. It is of no use whatever renewing any of the component parts of either carburetter, and the only cure is to make sure that the fuel tank and pipe lines are entirely free from any kind of foreign matter or sticky substance capable of causing this trouble. Needles Remove the piston and suction chamber assembly. Slacken the needle clamping screw, extract the needle, and check its identifying mark (see GENERAL DATA). Ret the correct needle, ensuring that the shoulder on the shank is ush with the piston base. Piston sticking The piston assembly comprises the suction disc and the piston forming the choke, into which is inserted the hardened and ground piston rod which engages in a bearing in the centre of the suction chamber and in which is, in turn, inserted the jet needle. The piston rod running in the bearing is the only part which is in actual contact with any other part, the suction disc, piston, and needle all having suitable clearances to prevent sticking. If sticking does occur the whole assembly should be cleaned carefully and the piston rod lubricated with a 0.14 136 spot of thin oil. No oil must be applied to any other part except the piston rod. A sticking piston can be ascer- tained by removing the piston damper and lifting the piston by pressing the piston lifting pin; the piston should come up quite freely and fall back smartly onto its seating when released. On no account should the piston return spring be stretched or its tension altered in an attempt to improve its rate of return. Section D.5 AIR CLEANERS The air intake lters are of the dry paper element type requiring no attention between lter replacement. The air lter casings should be removed and cleaned out periodically to remove any dust deposit. Filter replacement Disconnect the engine rocker cover breather pipe from the front lter (early cars). Unscrew the bolts securing each air lter to the choke bracket and xing plate respectively and remove the lters from the vehicle complete. Remove the base plate and throw away the old paper element. Clean the inside casing and intake tubes thoroughly and reassemble, using new paper elements. MGB. Issue 4. 15676