Weber Carburator Manual.pdf - Power by BMW E21

10-14 Part 2 Weber carburetors Chapter 10
79 Fit the retalnlrog ring (18 1and Insert 1M screws (171-
80 Align the merb on tl'le thennost.1 1115Mmbly (19) and
nou sing (2 7) fie centre mark). then ti ght en the reta ining screws
(171-
8 1 Press the li miter cap (6 5) onto the idle mixture screw 1661
w ith the extension pointing away from the main body abut ment.
8 CarblJrettor adjUltmenb
W ith the carburettor com plet ely assemb led. the follow ing
adjustments must be made prior to fitting It to the engine;
, Fully open the throttle. hold the choke valves full y open and
release the t hrottle. Turn the t hrottle idlin g adj ustment screw
(62) unt il it Just tOtJches the idle stop lever (56 ). than continue
to Sa'IW it in 1 complete tum.
2 Tum the idling mixture screw (66) in until it is in light
contact wi th its seat, the n back it off 1 co mple te tum.
3 Tum the secoodary throttle adjustment stop (44) unt il a ga p
of 0 .0 5 mm (O.D02 In) exists between the outer edge of m e
seconda ry throttl e val.... end the secondary berr ei. Check the
liiap w it h fee ler gauge s.
Vacuum pull down
4 Fit an elastic band to the choke lever (14) and over the
cover (11 so t hat it hold s the choke valves (3 1 $hut. Open the
throttl e to allow the choke valves to fu lly close .
5 Using a small electric ian's screw driver, push the cc ntect
ring on th e die phragm spin dle unt il the spindle is in firm contact
with the adjustment screw (24 ). Using a drill o r metal dowel,
check that the dis tance between the choke valve straight edges
and the Intake walls 15 as given in the Adjustment data under
maximum vacuum pull down.
6 To check the minimum vacuum pull down, use long nose
plier s to hold the diaphragm spindle in firm contact w ith the
adj ustment screw 1241.but make sure that the modulato r spring
Is compressed fully. Use a dri ll to make the check in the
identical manner to that given in paragraph 5. Note that on
some carburettor types the minim um vecuu m pull down can be
checked by inserting a screwdriver t hrough a hole in the
housing 12 7); on oth er models thilS hol e is blanked off.
7 If any of the dimensions checked in paragraphs 5 and 6 are
not correct, the adjustment screw (24) m ust be turned II
nacessary. This w ill necessit ate removing the seal (25) and the
owner must be satisfied thilt no legislation I, being contravened
by thi s action .
Choke phasing
8 Open the th rottle then release it ll nd position the fast idle
adju stin g screw (4 7) on the middle ste p of the fast idle cam.
9 Close the choke valves as fer ll S possibl e by turning the
choke lever 1141 antI-clock wi se. Usi ng 8 drill. check th at the
distance between the chok e valve straight edges and the inteke
w alls is as given in the Adjustment deta. If nat. carefu lly bend
the short arm on the shaft 115 1 as neeeeserv li e the int ernal
arm).
Dechoke adjustment
10 Open the throttl e and fully close the choke valves by turning
the chOke lever (14) ant i-cloc)(wise. Wh ile holding the lever
IT41. fully open the throttle. The distance between the choke
valve str aight edges and t he intake w ellS should be as give n in
the Adjustment dlta when checked with a suitable drill. If not,
bend the choke lever (2 9) as necessary.
F8st idle adjustment
1 1 Open the throttl e and position the fast idle edjusti ng screw
(4 7) on the highest section of the fast idle cern. Us ing II feeler
gauge. check that the dist ance between the prima ry th rottle
valve and the oute r barrel w all is as given In the Adju stment
data. If not. loosen the locknut (48) end t um the adjusting S(:rew
14 7) as necesmlry: tight en the locknut when the adjustment is
complet ed (pho to).
A
_-_ _ 0
Fig. 10.711M autom.tic ch oke ali gn ment marks (Sec 7 1
A Rich po sition
B Normalposition
C Leim position
Fig, 10.8 Checldng the va cu um pull down adjustment (Sec 81
A Diap hragm spindle
B Elastic btm d
C ScrewdrlvIr (only
possible on some types)
Fig . 10.9 Uaing a drill t o check t he vac uum pull down
dimension (Sec 8 )
A Drill
B Screwdriver