instruction sheet mercarb two-barrel

4/92©TECHUTCO.
PrtntMl I n U.S.A.
50-766-4
INSTRUCTION S H E E T
MERCARB TWO-BARREL
•
GENERAL EXPLODED VIEW
The general design and parts shown will vary to
individual units covered on this instruction sheet
DISASSEMBLY
U s e explcxled view a s guide. T h e numerical sequence may generally be foll o w e d to d i s a s s e m b l e unit far enough to permit cleaning and inspection.
NOMENCLATURE
Reference Number
Reference Number
1
S c r e w , C h o k e Housing
2
3.
4.
5.
6.
7.
8.
Choke Housing A s s e m b l y
9.
10.
11.
12.
13.
14
15.
16.
17.
18.
19.
2a
21.
22.
23.
24.
25
Gasket. C h o k e Housing
S c r e w , C h o k e Lever
Lever
S c r e w . Fast U l e C a m
Fast kjle C a m
Choke Rod
Pump R o d
S c r e w , B o w l C o v e r (Long)
S c r e w . B o w l C o v e r (Short)
Bowl Cover A s s e m b l y
Pin, Ftoat
Float
Needk!&Seat Assembly
P u m p Shaft & Lever A s s e m b l y
Screw, Pump Shaft Assembly
Washer, Pump Shaft
Retainer, P u m p S h a f t
Accelerator P u m p A s s e m b l y
Spring, P u m p A s s e m b l y
Retainer. Spring
Strainer
C h e c k Ban
Accelerator P u m p Lever
B © r "Washer, Inner
27
28.
29
30
31
32.
33
34.
35
36
37
38
39
40.'
41.
42
43
44
45.
46.
47
48
49
50.
51
52.
G a s k e t Bowl C o v e r
Fitting, Fuel Inlet
G a s k e t Fuel Inlet
Gasket. Fuel Inlet
S p n n g . Fuel Filter
Filter
P o w e r Valve Assemtily
G a s k e t Power V a l v e
Jet
Gasket. Jet
S c r e w . Ventuh A s s e m b l y
S c r e w . Venturi Center
Lockwasher
Gasket
Gasket
Ventuh Cluster
G a s k e t Venturi C l u s t e r
Fkjat B o w l A s s e m b l y
S c r e w . Throttle B o d y
Lockwasher
G a s k e t Throttle B o d y
Throttle Body
Needle. Idle M i x t i r e Adjusting
Spring, klle M i x t i r e S c r e w
S c r e w , kJle S p e e d Adjusting
-63
W a s h e r . Outer
CLEANING
Cleaning must be done with carburetor disassembled. U s e a carburetor cleaning
solvent to soak parts king ervxjgh to soften and r e m o v e aH foreign matenal.
M a k e certain the throttle b o r e s are free of all carbon and varnish deposits.
Rinse off in suitable s o l v e n t B l o w out all p a s s a g e s in c a s t i n g s w i t h c o m p r e s s e d
air and c h e c k carefully to ensure tftorough cleaning of o b s c t r e areas
C A U T I O N : Do not s o a k f l o a t solenoids, diaphragm
units, plastic w a s h e r s
wfien used or rubber parts In cleaning solvents. Do not sand, wire brush or file
o n Tefton-coatad stwfts.
REASSEMBLY
R e a s s e m b l e in reverse order of disassembly. Note special instructions and
follow numerical outline in making adjustments necessary for cartxiretor being
serviced.
SPECIAL INSTRUCTIONS
Idle ac^usting needles: T i s n e a c h needle in lightly until seated, then back out
t w o turns. (Do not install idle limiter c a p s at this time.)
Air Horn Tightening Sequence
T h e s p e c i f i c a t i o n s in t h i s c h a r t r e p l a c e t h e s p e c i f i c a t i o n s f o u n d in the s e r v i c e m a n u a l s . S e e M e r C r u i s e r S e r v i c e B u l l e t i n 9 7 - 8 .
CYL
MODEU
CARBURETOR
CHOKE
CHOKE
FLOAT
ENGINE
NUMBER
FLOAT LEVEL
FLOAT DROP
PUMP ROD
SETTING
UNLOADER
WEIGHT
M C M 120/140
1389-8490A2
1-3/32" (27 m m )
1-5/32" ( 2 9 m m )
9 Grams
1389-9350A2
1-3/32" (27 m m )
1-5/32" ( 2 9 m m )
5/64- (2mm)
9 Grams
M C M 120/140
1389-9562A 1
1-3/32" (27 m m )
1-5/32" ( 2 9 m m )
5/64" {2mm)
9 Grams
M C M 2.5L/3.0L
3310-806077A2
1-3/32" (27 m m )
1-5/32" ( 2 9 m m )
5/64" ( 2 m m )
9 Grams
M C M 2.5/3.0L
3310-860070A2
1-3/32" (27 m m )
1-5/32" ( 2 9 m m )
5/64" {2mm)
9 Grams
M C M 3.0L
1389-815396A2
1-3/32" (27 m m )
1-5/32" ( 2 9 m m )
5/64" ( 2 m m )
9 Grams
M C M 3.0L
3310-806078A2
1-3/32" (27 m m )
1-5/32" ( 2 9 m m )
1 Lean
clockwise
1 Lean
clockwise
1 Lean
clockwise
1 Lean
clockwise
1 Lean
clockwise
1 Lean
clockwise
1 Lean
5/64" (2mm)
M C M 120/140
3/8" ( 1 0 m m ) Solid-Needle
* 9/16" ( 1 4 m m ) Sprinq-Needle
3/8" ( 1 0 m m ) Solid-Needle
* 9/16" ( 1 4 m m ) Sprinq-Needle
3/8" ( 1 0 m m ) Solid-Needle
* 9/16" ( 1 4 m m ) Sprinq-Needle
3/8" ( 1 0 m m ) Solid-Needle
• 9/16" ( 1 4 m m ) Spring-Needle
3/8" ( 1 0 m m ) Solid-Needle
* 9/16" ( 1 4 m m ) Spring-Needle
3/8" ( 1 0 m m ) Solid-Needle
• 9/16" ( 1 4 m m ) Spring-Needle
3/8" ( 1 0 m m ) Solid-Needle
* 9/16" ( 1 4 m m ) Sprinq-Needle
3/8" ( 1 0 m m ) Solid-Needle
• 9/16" ( 1 4 m m ) Spring-Needle
3/8" ( 1 0 m m ) Solid-Needle
• 9/16" (14mm) Sprinq-Needle
9/16" (14mm) Sprinq-Needle
3/8" (10mm) Solid-Needle
• 9/16" (14mm) Sprinq-Needle
3/8" ( 1 0 m m ) Solid-Needle
* 9/16" (14mm) Sprinq-Needle
3/8" ( l O m m ) Solid-Needle
• 9/16" (14mm) Sprinq-Needle
3/8" (10mm) Solid-Needle
• 9/16" (14mm) Sprinq-Needle
3/8" ( l O m m ) Solid-Needle
* 9/16" ( 1 4 m m ) Spring-Needle
3/8" ( 1 0 m m ) Solid-Needle
* 9/16" ( 1 4 m m ) Spring-Needle
5/64" ( 2 m m )
9 Grams
5/64" ( 2 m m )
9 Grams
5/64" {2mm)
9 Grams
M C M 3.0L
3310-807504A 1
M C M 3.0L
3310-864940A01
M C M 3.0L TKS
M C M 3.0LX
3310-866140A02
1389-815397A 2
MCM 3.0LX
3310-805924A2
MCM 470
1389-8489A5
M C M 170/165
1389-9564A 1
M C M 165/3.7L
3310-806079A 2
M C M 165/3,7L
3310-860071A 2
M C M 175/185
3304-9353A 2
M C M 175/4.3L
3304-9565A1
MCM4.3L
3304-9565A 7
MCM4.3L
3310-806080A2
3/8" (10mm) Solid-Needle
* 9/16" (14mm) Sprinq-Needle
3/8" ( 1 0 m m ) Solid-Needle
* 9/16" ( 1 4 m m ) Sprinq-Needle
•3/8" (10mm) Solid-Needle
• 9/16" (14mm) Spring-Needle
3/8" (10mm) Solid-Needle
M C M 4 3L
3310-806972A 1
• 9/16" (14mm) Spring-Needle
9/16" (14mm) Spring-Ns-eaFe
1-3^Ji^7TriYtr)
1-5/32" ( 2 9 m m )
M C M 4.3L
3310-807764A 1
9/16" (14mm) Spring-Needle
1-3/32" (27mm)
1-5/32" ( 2 9 m m )
M C M 4.3L
3310-864941A01
9/16" (14mm) Spring-Needle
1-3/32" (27mm)
1-5/32" { 2 9 m m )
MCM 4.3L TKS
3310-866141A02
9/16" (14mm) Spring-Needle
M C M 898/200
1389-8488A2
1-3/32" (27 m m )
1-3/32" (27mm)
1-5/32" ( 2 9 m m )
M C M 200
1389-9563A 1
1-3/32- (27mm)
1-5/32" ( 2 9 m m )
M C M 200/5.0L
1389-9670A2
1-3/32" (27mm)
1-5/32" { 2 9 m m )
MCM 5.0L
3310-806081A 2
3/8" (10mm) Solid-Needle
* 9/16" (14mm) Spring-Needle
3/8" (10mm) Solid-Needle
• 9/16" (14mm) Spring-Needle
3/8" (10mm) Solid-Needle
• 9/16" (14mm) Spring-Needle
9/16" (14mm) Spring-Needle
1-3/32" (27mm)
1-5/32" ( 2 9 m m )
M C M 5 0L
3310-861080A 1
9/16" (14mm) Spring-Needle
1-3/32" (27mm)
1-5/32" ( 2 9 m m )
M C M 5.0L
3310-861448A 1
11/32" (9mm) Spring-Needle
15/16" (24mm)
1-5/32" ( 2 9 m m )
M C M 5.0L
3310-864942A03
11/32" (9mm) Spring-Needle
15/16" (24mm)
1-5/32" { 2 9 m m )
M C M 5.0L TKS
MCM 5.7L
3310-866142A03
3310-807312A 1
11/32" (9mm) Sprinq-Needle
9/16" (14mm) Spring-Needle
15/16" (24mm)
1-3/32" (27mm)
1-5/32" ( 2 9 m m )
MCM 5.7L
3310-861245A 1
11/32" (9mm) Spring-Needle
15/16" (24mm)
1-5/32" ( 2 9 m m )
MCM 5 7 L
3310-864943A01
11/32" (9mm) Spring-Needle
15/16" (24mm)
1-5/32" ( 2 9 m m )
MCM 5 7 L TKS
3310-866143A03
11/32" (9mm) Spring-Needle
15/16" (24mm)
4
6
8
1-3/32" (27 m m )
1-5/32" ( 2 9 m m )
1-3/32" (27 m m )
1-5/32" ( 2 9 m m )
1-3/32" (27 m m )
1-3/32" (27 m m )
1-5/32" ( 2 9 m m )
1-3/32" (27 m m )
1-5/32" ( 2 9 m m )
1-3/32" (27mm)
clockwise
1 Lean
clockwise
1 Lean
clockwise
5/64" ( 2 m m )
9 Grams
9 Grams
5/64" {2mm)
9 Grams
1-5/32" ( 2 9 m m )
1 Lean
clockwise
1 Lean
clockwise
INDEX
5/64" ( 2 m m )
9 Grams
1-3/32" (27mm)
1-5/32" ( 2 9 m m )
INDEX
5/64" {2mm)
9 Grams
1-3/32" (27mm)
1-5/32" ( 2 9 m m )
INDEX
5/64" { 2 m m )
9 Grams
1-3/32" (27mm)
1-5/32" ( 2 9 m m )
INDEX
5/64" (2mm)
9 Grams
1-3/32" {27mm)
1-5/32" ( 2 9 m m )
5/64" ( 2 m m )
9 Grams
1-3/32" (27mm)
1-5/32" ( 2 9 m m )
5/64" {2mm)
9 Grams
1-3/32" (27mm)
1-5/32" ( 2 9 m m )
5/64" (2mm)
9 Grams
1-3/32" (27mm)
1-5/32" ( 2 9 m m )
2 Lean
clockwise
2 Lean
clockwise
2 Lean
clockwise
2 Lean
5/64" {2mm)
9 Grams
5/64" { 2 m m )
9 Grams
5/64" {2mm)
9 Grams
5/64" {2mm)
9 Grams
2 Lean
clockwise
2 Lean
clockwise
2 Lean
clockwise
2 Lean
clockwise
2 Lean
clockwise
5/64" {2mm)
9 Grams
5/64" ( 2 m m )
9 Grams
5/64" ( 2 m m )
9 Grams
5/64" (2mm)
9 Grams
5/64" {2mm)
9 Grams
2 Lean
clockwise
2 Lean
clockwise
5/64" {2mm)
9 Grams
5/64" {2mm)
9 Grams
2 Lean
clockwise
2 Lean
clockwise
2 Lean
clockwise
5/64" {2mm)
9 Grams
9 Grams
5/64" {2mm)
9 Grams
5/64" {2mm)
9 Grams
clockwise
2 Lean
clockwise
2 Lean
clockwise
2 Lean
clockwise
9 Grams
9 Grams
* Note: On engines experiencing flooding or rough idle, if all components and specifications are okay, it may be necessary to change to the
spring-loaded needle & seat assembly. Installing a spring loaded needle and seat on a 4-cylinder engine can cause a lean out
condition in extremely hard turns. (GM 153,181 old: Right turn.) (Mercury Marine 224 cid: Left turn.)
Because of this potential lean out condition in extremely hard turns, you should make the boat owner aware of this condition before
installing the spring-loaded needle and seat kit The spring loaded needle and seat kit is the preferred one to use if you have a flooding
problem at idle RPM. See MerCruiser Service Bulletin 97-8 for further information.
ADJUSTMENTS
SEE DATA TABLE FOR M E A S U R E M E N T S
0
TURNAIRHORNUPSBEOOWNPIVOTFLOAT
A S S a i B L Y UP AND CX3VM ON HR46E PtN TD B J S U R E
CT MOVES F R E a y :
IMPORTANT; B B K J H E C H E C K I N G FLOAT L B « ,
RAISE FLOAT AHO ALLOW ITTO NUX:HOWEVER
Q
HOLOAIRHORNRMMTSBEUPTDALLOWFLOATTO
HANGFRS
@
^
1*JTHGASt<ETWPLACtMEASUREFLOATDR0P
FROM THE GASKET TO TVE TOE O f T « FLOAT
OOmrFORCeDOymmUKtBYHAMD.
®
M T H S A S K E T IN P L A C E , M E A S U R E F L O A T LBffl.
fWOM T V * G A S K E T T O T>eTOE O F T W F L O A T
TO ADXISi; BSCI
aOATAfM
I - MEASURE FROM DOT ON FLOATTO GASKET (SffiFXS. 5 )
OVr FLOAT L » E L ACLUSTMBrr
RG.1
50-766-4