MG MGB - Page 29

ENGINE
TUNING
DATA
18GD
AND 18GG
ENGINES
ENGINE
Type
.
Displacement
..
Firing order
.
Compression
ratio:
H.C.
L.C.
Compression
pressure:
H.C.
LC.
Idle speed
..
Valve rocker clearance
Static
ignition timing:
H.C.
L.C.
Stroboscopic
ignition
timing:
H.C.
L.C.
Timing mark location
DISTRIBUTOR
Make/Type
Contact breaker
gap
..
Contact
spring tension
Rotation of
rotor
Dwell angle
Centrifugal
advance
Crankshaft
degrees/Speed
(vacuum
pipe
disconnected)
Vacuum
advance
Starts
Finishes
Total
crankshaft degrees
IGNITION COIL
Make/Type
Resistance:
Primary
..
SPARKING
PLUGS
Make/Type
Gap
CARBURETTERS
Make/Type
Jet
Needle
Piston
spring
ELECTRICAL
Alternator
Battery
..
.
Volts/Polarity
..
e"
Starter
Regulator
Tuning
Data 2
18GD—18GG.
109.8
cu.
in.
(1798
c.c.).
1, 3, 4,
2.
8.8
:
l.
8.0
:
l.
160
lb./sq.
in.
(11.25 kg./cm.2).
1301b./sq.
in.
(9.15 kg./cm.2).
500
r.p.m.
.015
in.
(.38 mm.)
set
cold.
10°
B.T.D.C.
8°
B.T.D.C.
14°
B.T.D.C.
at
600
r.p.m.
12° B.T.D.C.
at
600
r.p.m.
Pointer
on
timing
case,
notch
on
crankshaft pulley.
Lucas/25D4.
.014
to
.016
in.
(.35
to
.40
mm.).
18
to
24
oz.
(510
to
680
gm.).
Anti-clockwise.
60°i3°.
SERIAL
NUMBER
SERIAL
NUMBER
40897
(H.C.)
40916
(L.C.)
4°
at
600
r.p.m.
6°
at
600
r.p.m.
6°
at
700
r.p.m.
8°
at
800
r.p.m.
9°
at
900
r.p.m.
9°
at
1,000
r.p.m.
15°
at
1,600
r.p.m.
18°
at
3,000
r.p.m.
20°
at
2,200
r.p.m.
24°
at
4,400
r.p.m.
5
in.
Hg
4
in.
Hg
(127
mm.
Hg).
(101.6
mm.
Hg).
13
in.
Hg
12 in. Hg
(330.2
mm.
Hg).
(304.8
mm.
Hg).
20°:t2°.
16°i2°.
Lucas/HA12.
3.1
to
3.5 ohms
at
20°C.
(68° F.).
Champion/N9Y.
.024
to
.026
(.625
to
.66
mm).
SU/HS4.
.090
in.
(2.2
mm.).
Standard,
FX; Rich,
No.
5
;
Weak,
GZ.
Red.
18GD,
Lucas 16AC,
18GG,
Lucas 16ACR.
Lucas
CA9E
early
cars,
Lucas BT9E
or
BTZ9E.
l2-volt/NEGATIVE
earth.
Lucas M418G
Pre-engaged.
Lucas
4TR
(18GD
only).
MGB.
Issue2. 25729