Weber Carburator Manual.pdf - Power by BMW E21

Part 1 Introduction
Chapter 4 Overhaul
Conte nts
s.ction
Accelerator pumps ......................................................................... 18
Carburetor body and cover s 8
Choke valves ............... 13
Cleariing 6
Disassembly 5
Fiber washers and diaphragms. ..................................................... 17
Float assemblies •.••••..................••••.•••••••.•••••••............••••••••••.••••••••• 15
Inspection and repair 7
Introducti on ..........................................•.•.....•..........................•....•. 1
1 Introduction
Ove rhau ling of the carbu retor becomes necessary when the
compo nent parts are worn to such an extent that they are no long er
serviceable or efficient in operation. The manufactu rers recommend a
gene ral overhaul inte rval of 60,000 miles (97,OOO km) but much will
d epend on the op erati ng conditions and this may well have to be
reduced in certain circumstances. However, If the maintenance and
servicing procedures as given in Chapter 3 have been regularly carried
out from new , this interval is a good guide to work to.
At the time of the overhaul th e carburetor must be removed,
disassembled , cle aned, inspected , repai red as nec essary ,
reassembled and reinstalled. This Chapter incl udes th e genera l
overhau l procedures wh ich apply to all carburet ors but any special
procedures, part icularly th ose including the use of specialized tools,
are included in the chapters dealing with specific carbure tor types.
. The work involv ed is with in the capabiliti es of most hom e
mechan ics, alth ough in ord er to effect a first cl ass overhau l it is
import ant no t to rush the work. Weber, Zen it h Str omberg and SU
carburetors are manufactured to a high deg ree of workmanship and
therefore must be treated as precision instruments; arthough they are
manufactu red 10 withstand the most adverse road conditions they also
incorporate some extrem ely sensitive mechanisms.
Extens ive workshop equipment is not required and the majority of
wo rk can be carried out using the normal tools contained in a
motorist' s tool kit. How ever there are certain inst ances where a special
tool is required and these are qu oted in the relevant chapters of this
Manual.
Before starting work it is recommended that the home mechanic
reads all the relevant Ch apters of th is Man ual in order to acq uaint
himself with all the necessary procedures and spare partS required. By
obtaining t he spares and t ools beforehand, th e ov erhaul will be
4·1
Section
Jets and emulsion tubes................................................................ 14
Matenals.................................................................. 3
Needle valves................................................................................. 16
Spare parts. 4
Throttl e levers and return springs 11
Thrott le spindles and choke spindles 10
Throttle valves 12
Tools ............................................................................................... 2
Venturis and cooses , :...... 9
completed in the shortest time, and there will be little incon vooience
due to the carbeing off the road.
2 T ools
Note : In addition to the following list the tools necessaryto cany out
any special overhaul procedures as given in the relevant Chapterofthis
Manual. must be obtained. (refer to Fig. 1 through 4)
Wrench es, open -ended metric
Wrenches, ring metric
SCreWdrtvers, large medium sna smail (flat bladed)
Curved metal scraper
Surface plate orthickpiece of plate glass
Steefstraight-wge
Hard bristle tJrus/l
Small feele r gauges
Vernier calipers Of' depth gauge
Latge clean tray
Open-topped containers suitable for gascline
Pi{>& cleaners
Foot-operated tire pump
Ught tlammer
Center punch
Smallfiles, flat and round
Hand drill
Flat metal scraper
Where nec essa ry, the fo llowing tools shou ld be ob ta ined from a
spec ialty tool shop;
set of jet gauges
Thread tap and tap holder
Threaddie and die holder
1