MG MGB TOURER GHN5 Handbook page 75

If a smooth idle a t the correct speed and balance is not obtainable, adjust the
idle speed mixture setting as follows.
11. Stop the engine. Remove each suction chambe~ and piston and screw the jet
adjusting screw (6) in until the jets are flush with the bridge of the carburetter
or as high as possible without exceeding the height of the bridge. Turn the
jet adjusting screw (6) on each carburetter clockwise 2+ turns. Refit the
piston and suction chambers and top up the piston damper oil levels.
NOTE.-This operation need not be carried out if it is known that the jets
are in the same relative position.
12. Restart the engine and run it at idle speed.
13. Turn the jet adjusting screw (6) o n each carburetter clockwise to enrich or
anti-clockwise to weaken, by the same amount until the fastest speed is
indicated; turn each screw anti-clockwise until the engine speed just com-
mences to fall. Turn each screw very slowly clockwise by the minimum
amount until the maximum speed is regained.
14. Using the exhaust gas analyser, check that the percentage CO reading is
within the prescribed limits. If the reading falls outside the limits, reset both
jet adjusting screws by the minimum amount necessary to bring the reading
just within the limits.
15. Re-check the idle speed and carburetter balance and adjust as necessary
with the throttle adjusting screws.
16. Set the throttle interconnection clamping levers so that the link pin is ,012 in.
away from the lower edge of the forks (see inset 10) as follows:
17. Stop the engine and slacken both clamping bolts (9) on the throttle spindle
interconnection.
18. Insert a 0.060 in. feeler gauge between the throttle shaft lever and the cold
start interconnection rod. Move each lost motion pick-up lever in turn until
the tag of the lever rests on the lower arm of the carburetter throttle fork.
Tighten the clamping bolts (9, Fig. 7) on each fork, ensuring that there is
approximately in. end-float on the interconnection rod. Remove the
feeler gauge. The pins on the throttle spindle lever should then have clear-
ance (10) in the throttle fork.
19. With the fast idle cams of both carburetters against their respective stops,
set the cold start interconnection so that both cams commence to move
simultaneously.
20. With the fast idle cams against their stops check that a , $ in. free movement
of the mixture control (choke) cable exists before the cable moves the cams.
21. Run the engine at 1,500 r.p.m. and check the carburetters for balance.
22. Pull out the mixture control (choke) until the arrow (7) marked o n the cam
is positioned under the fast idle adjusting screw (8) of each carburetter.
23. Using the balancing meter to ensure equal adjustment, turn the fast idle
adjusting screws to give the correct fast idle speed (see 'GENERAL DATA').
Stop the engine.
24. Refit the air cleaners.