
The  interior of the  car can  be heated by the engine
warmed air being ducted into the front compartment and
controlled  by a  lever on the heating system tunnel.
Engine ignition is by a battery, ignition coil and distribu-
tor which  is driven  by a  gear on the camshaft. The engine
is started  by an  electric starter motor which is mounted on
the gearbox casing  and  is controlled by a lever located
behind the gearchange lever.
The complete power unit is mounted  by a spring support
at the centre of the rear  b o d y  crossmember and  by t w o
rubber pads mounted laterally to the gearbox.
1 :2  Engine removal (sedan—all versions)
To remove the engine from the car proceed as follows:
Raise t h e rear of t h e car and place on firmly based
stands placed under suitable brackets on the underside
of the  body.
Disconnect the battery positive terminal clamp from the
battery terminal post. Release the clip securing the main
petrol  pipe to the tank sender unit and ease  t h e  pipe
from the unit. Drain the oil from the engine sump into
a suitably sized  container.
D i s c o n n e c t  t h e   rear  number plate light wire  (see
FIG 1 : 6) . Release t h e engine compartment lid check
strap from  its slot  and separate the lid from the body by
sliding the  hinge apart.
Remove the cables attached to the ignition coil, also
to the generator and the starter motor. Remove the
starter motor control tie rod. 
Release the oil pressure
indicator cable, the main petrol pipeline at the pump,
the accelerator and starting device controls.
Remove the t w o  hoses of the heating and cooling
system which are the input hose to the blower and the
hose for the car heating system. Release and lift out the
engine apron. Remove the starter motor mounting bolts
and carefully lift away the  motor.
Using a garage hydraulic jack with  suitable cradle (see
FIG 1 : 7)  or a rope sling relieve the engine weight
from its mountings. Remove the nuts securing  the
gearbox to the engine and the flywheel  protection
apron.
Remove the bolts fixing the elastic support to  the cross-
member. Remove the rear  crossmember mounting nuts
noting that the engine earth cable is held  by one
mounting nut and lift away the crossmember.
Carefully ease t h e engine away from the gearbox
ensuring that there is no strain  placed on the clutch
shaft.  Lower the engine to the floor taking care that no
weight is allowed on any of the attachments. 1
2
3
4
5
6
7
8
1 :3  Engine removal (station wagon)
To remove the engine from the station wagon proceed
as follows:
1  Raise t h e  rear of the vehicle and place on firmly based
stands placed  under suitable brackets on the  underside
of the  body.
2 Disconnect the battery positive terminal  clamp from
the battery terminal  post.  Release the clip securing the
main petrol pipe to the tank sender unit and ease the
pipe from the unit. Drain the oil from the engine sump
into a clean dry container of suitable size.
3   H o l d  t h e  rear  door  open   and  secure using string to stop
it swinging to the closed position. Secure the luggage
compartment floor panel in its upright position.
F50013 4 Remove the cables attached to the ignition coil, also
to the generator and starter motor. Remove the starter
motor control tie rod. Release the o i l pressure indicator
cable, the main petrol pipeline at the pump, the accele-
rator and starting device controls. Disconnect the air
filter housing.
5 Remove the hose connecting the car heating system
to the  engine cowling. Disconnect the clip holding the
air pipe to the blower and carefully disconnect the pipe
from the blower cowling. Remove the starter motor
mounting  bolts and carefully lift away the motor. FIG 1:5  120.000 engine assembly: cross-section view
through a cylinder 

LID CHECK A R M
FIG   1:6   Engine  compartment  lid  open LID LOCKING
HOOK
NUMBER PLATE
LAMP CABLE NUMBER PLATE LAMP
CABLE JUNCTION
CROSS  MEMBER  ARR.2O74.
FIG  1  :7   Engine  removal using  the  jack with cross-
member  Arr.2074
6 Using a garage hydraulic jack with a suitable cradle
relieve the engine weight from  its mountings. Remove
the nuts securing the gearbox to the engine.
7 Remove the nuts securing the rear  bumper blade and
panel to the body.  Note that the engine earth cable is
held by one mounting nut. Carefully dismantle the
engine elastic mounting or release the bracket from the
engine rear  cover  by  removing the two nuts and  washers.
Lift  away  t h e  rear  panel  assembly carefully making sure
14
FIG  1 : 8   Engine  components: crankcase, cylinder head,
timing sprockets cover To dismantle the engine proceed as follows:
1 Remove the exhaust silencer by releasing the two
collars for attachment to the engine and the two con-
nections for the exhaust pipe.  It will be noted that
there is one exhaust pipe connection on either side
of the  cylinder head.
2  Place the engine on  a firm wooden top bench. Remove
the two tappet cover retaining nuts and washers and
lift away the cover.  Remove the connection for cooling
air delivery to the sump cooling ducts at the side of
the sump.
3 Remove the air cleaner after first releasing the two
bolts on the air cowling and the two nuts for the air
elbow connection to the carburetter.
4 Remove the generator drive belt by releasing the
three nuts so splitting the semi-pulley.  Lift away the
drive belt.
5 Remove all the bolts securing the air conveyor
ducting to the cylinder head, to the crankcase and
also to the engine cowling assembly opposite to the
air conveyor.  Release the accelerator control tie rod
and carefully lift away the air conveyor assembly
complete with the generator after first removing the
clamp fixing the generator to the  crankcase. 1 :4  Engine disassembly (sedan—all versions) t h a t  rear  air  ducting panels are not strained or the
mating faces damaged.
8 Carefully ease  the  engine away from the gearbox ensur-
ing that there is no strain placed on the clutch shaft.
Lower the engine to the floor taking care that no weight
is allowed on any of the attachments. 

6 Release the ignition distributor support retaining nut
and lift away the distributor together w i t h  its support.
7  Remove all the mounting  bolts of the engine cooling
cowling and  lift away the assembly.  Release the t w o
carburetter retaining nuts and carefully remove the
carburetter together with  its drip  tray.
8 Lift away the valve rocker assembly having first
released the t w o retaining nuts together with the plain
washers and lock washers. Carefully lift out the valve
rocker pushrods noting their relevant positions.
9  Slacken the four central cylinder head cap nuts and
the four conventional nuts in the order, shown  in
FIG  1 :44 or 1 :46. Lift the cylinder head from the
barrels. If difficulty is experienced it is essential to use
Fiat tool A.40014 or a similar drilled plate, otherwise
serious damage could be caused if other means are
used (see FIG 1:9).
10 Remove the four pushrod sleeves and the casing
containing the oil ducting to the overhead valve gear.
11 Remove the fuel pump retaining nuts and washers
and lift away the pump.  Carefully pull out the pump
control pushrod from the crankcase.
12 Remove the six screws holding the centrifugal oil filter
pulley cover and  lift away the cover. Remove the
centrifugal filter mounting flange by unscrewing the
crankshaft central bolt. Also remove the timing cover
containing the oil pump gears and the oil  pressure
regulating valve.  Note the position of the nuts,
toothed and plain 
washers for correct reassembly.
13 Release t h e four camshaft sprocket retaining bolts and
lift away the sprocket and timing chain. Using Fiat
pulley A.46020 or a  large universal two-leg puller as
shown in FIG 1 :10 remove the crankshaft sprocket
and its body.
14 Carefully lift out the  rocker pushrod tappets making a
note of their location and gently pull out the camshaft
making sure the front bearing bore is not damaged  by
the cam lobes or distributor drive gear.
15 Mark the flywheel and crankshaft to ensure correct
reassembly and  release the six f l y w h e e l retaining bolts
together w i t h the  lockwashers and  lift away the fly-
wheel.
16 Using Fiat tool A.60156 on the two central studs, lock
the two cylinder barrels in place as shown  in FIG 1  : 1 1.
TOOL A. 40014
FIG  1:9  Tool A.40014 for cylinder head removal
F50015
17 Turn the engine upside down ensuring that no weight
is placed on the studs and remove the  oil sump and  the
oil suction scoop.
18 Mark the connecting rods and end caps to  ensure
correct reassembly and  remove the end  caps.  Place the
engine on  its side and remove the cylinder barrels
clamp. Ensure that the studs are clean  and carefully
slide off the connecting rod-piston-cylinder assem-
blies from the crankcase.
19 Remove the six screws holding the rear  main bearing
housing to the crankcase and  lift away the housing.
Remove the six screws holding the front main bearing
housing to  the crankcase and  lift away the  housing.
20 Carefully ease the  crankshaft from the crankcase
moving it diagonally to assist withdrawal. FIG 1:11  Cylinder hold-down tool A.601 56 TOOL A.60156 FIG 1 :10  Removing crankshaft sprocket w i t h puller
A.46020
PULLER  A.46020 

STUD REMOVAL
PULLER  40010
FIG 1 :12  Removal of stud from crankcase by puller
A.40010
FIG  1  :13   Engine  without blower cowling and cylinder
head  cover.SPACER  A N D  CONNECTION
FOR ROCKER SHAFT
LUBRICATION TUBE
OILVAPOR
.VENT PIPE
CASINGS FOR PUSHRODS
(AND OIL RETURN
TO CRANKCASE
21 To ensure no damage occurs to the long  cylinder
barrel mounting studs these may be removed using
Fiat puller A.40010 or a universal stud removal as
shown in FIG 1 :12.
1 :5  Engine disassembly (station wagon)
To dismantle the engine proceed as follows:
1 Remove the exhaust silencer and manifold by releasing
the four  nuts holding the two flanges from the  cylinder
head. Also disconnect the two silencer mounting
brackets and  lift away the exhaust system (see
FIG 1 : 2).
2  Place the engine on  a firm wooden top bench. Release
the clip  holding the tappet cover and  lift away together
with the drip tray.  Disconnect the fuel line and throttle
linkage at the carburetter and carefully lift away the
carburetter together with its insulator joint and gaskets.
3 Remove the generator drive belt by releasing the three
nuts so splitting the semi-pulley. Lift away the drive
belt.
16
FIG 1 :14  Tool  A.60084 for valve and  valve springremoval
TOOL  A .  60084
4  Remove all the bolts securing the air conveyor ducting
to the cylinder head and to the crankcase, carefully
separate the  panels and  lift away the separate panels
ensuring no damage  is caused to the mating faces.
5 Release the ignition distributor retaining bolt and lift
away the distributor.
6 Remove the fuel pump retaining bolts and  also the
three fuel pipe  retaining  clips and  lift away the fuel
pump assembly together with the insulator, gaskets
and control rod.
7  Release the t w o valve rocker retaining nuts, note the
order of assembly of washers and ease  away the rocker
shaft assembly from  the top of the cylinder head.
Carefully lift out the valve rocker pushrods noting
their relevent positions for correct reassembly.
8 Slacken the four cylinder head cap nuts and the four
conventional nuts in the order shown in FIG 1  :46. Lift
the cylinder head  away from the barrels. If difficulty is
experienced it is essential to use Fiat tool A.40014 or a
similar drilled  plate as shown  in FIG 1 :9, otherwise
serious damage could be caused if other means are
used.
9 Remove the four pushrod sleeves and the casing con-
taining the oil ducting to the overhead valve gear.
10  Remove the six screws holding the centrifugal oil filter
pulley cover and  lift away the  cover. Remove the
centrifugal filter mounting flange by unscrewing the
crankshaft central bolt. Also remove the timing cover
f r o m   t h e  rear  of  t h e  crankcase. Note carefully the posi-
tion of the nuts, toothed and plain washers for correct
reassembly.
11  Release the four camshaft sprocket retaining bolts
and  lift away the sprocket and timing chain. Using
Fiat puller A.46020 or a large universal two-leg puller
as shown  in FIG  1 : 1 0  remove the crankshaft
sprocket and its key
12 Carefully lift out the rocker pushrod tappets making a
note of their location and gently pull out the camshaft
making sure that the front bearing bore is not
damaged by the cam lobes. 

13  Remove all the bolts and washers joining the sump
casting to the crankcase making a special note of the
location of bolts of different lengths.
14 Mark the flywheel and crankshaft to ensure correct
reassembly and  release the six flywheel retaining bolts
together with the lockwashers and  lift away the fly-
wheel.
15 Using Fiat tool A.60156 on the two central studs, lock
the t w o cylinder barrels in place  (see FIG 1 :11).
16  Turn the engine upside down ensuring that no weight
is placed on the studs.
17 Mark the connecting rods and end caps to ensure cor-
rect reassembly and  remove the end  caps.  Place the
engine on  its side and remove the cylinder barrels
clamp. Ensure t h a t t h e studs are clean and carefully
slide off the connecting rod-piston-cylinder assem-
blies from  the crankcase.
18 Remove the six screws holding the rear  bearing hous-
ing to the crankcase and  lift away the housing. Remove
the six screws holding the front main bearing housing
to the crankcase and  lift away its housing.
19 Carefully ease  t h e  crankshaft from the crankcase
moving it diagonally to assist w i t h d r a w a l .
20 To ensure no damage occurs to the long cylinder
barrel mounting studs these may be removed  using
Fiat puller A.40010 or a universal stud remover as
shown in FIG 1 :12.
1 :6  Cylinder head removal, servicing and replace-
ment
Description:
The aluminium cylinder head is finned to increase the
cooling surface. Through bolts secure the head and the
two cylinders to the crankcase. The valves are controlled
by a  camshaft through tappets, pushrods and rockers. The
connection between the head and the crankcase is via five
sleeves mounted directly between the head and crankcase,
and these accommodate the pushrods, lubricating oil and
passage for the crankcase gases. The cylinder head has
been 
modified for the 110 F and later 120 engines as
they now incorporate a heater safety device as described
in Section 4 : 4 .
FIG 1:15  Cylinder head
17F500
The cylinder head  should  be removed whenever the
valves require attention  or the engine to be decarbonized.
To remove the cylinder head proceed as f o l l o w s :
1 Remove the air cleaner, carburetter, rocker cover and  the
screws securing the blower conveyor to the cylinder Removal of cylinder head: FIG 1 :17  Installing a valve guide using  Tool A.60153
provided with pilot bush TOOL A. 6 0 1 5 3 -
WITH PILOT BUSH FIG 1:16 Cleaning valve guides
W I R E  BRUSH  A.11417  /  BIS 

INTAKEEXHAUSTINTAKEEXHAUST
FIG 1 :18  Main specifications of intake and exhaust valves and valves guides (dimensions in  mm)
head. Disconnect the t w o side exhaust manifolds.
Note the spark  plug  HT cables locations and dis-
connect from spark plugs.
2 Remove the rocker shaft pedestal- and lift away the
rocker gear.  Extract the pushrods, making a careful
note of their location. Remove the cylinder head hold
down nuts in the order shown in FIG 1  :44 and using a
puller as shown  in FIG 1 :9 lift off the head.
Dismantling the cylinder head:
1 Using Fiat valve spring compressor A.60084 or a uni-
versal spring compressor depress the valve spring as
shown in FIG 1  :14 and  lift out the  cotters. Release t h e
compressor and withdraw the lock cone, oil shield
(inlet valve only) upper spring cup, valve spring and
lower spring cup. Withdraw the valve from the under-
side of the head.
2 Dismantle the remaining three valve assemblies as
detailed above ensuring that all  parts are kept in sets
for correct reassembly.
Inspection and servicing of the  cylinder head :
1 Remove all carbon deposits from the combustion
chambers and valve ports using a rotary wire brush or a
set of scrapers.
2  Thoroughly clean the cylinder head and to test for dis-
tortion lightly coat the  machined faces with 'Engineers
Blue' or lamp 
black and  place the cylinder head on a
surface plate. Carefully slide to and fro and any streaks
left behind will indicate a distorted surface. A distorted
head will not make a gas-tight seal with the cylinders
and must be entrusted to an  expert for correction or,
in severe cases, renewed.
3  Carefully clean the valve guides as shown in FIG 1:16
using Fiat guide brush A.11417 bis. Should the guides
18Reassembly is the reverse procedure to dismantling.
During assembly utmost cleanliness must be observed as
any abrasive material could find its way to the pistons and
cylinder bores causing unnecessary wear. Check that the
cylinder barrel mating face is clean to ensure correct
gasket sealing.Reassembly  of  t h e  cylinder head:
be worn then they should  be removed using a press and
a suitable sized drift. The guides are press fitted with a
pinch fit of .00134 to .00244 inch. To install the guides
use Fiat tool A.601 53  as shown in FIG 1 :17. As the
guides have no stop ring during the press fitting, the
depth of insertion is determined by the Fiat tool. If the
tool is not available take the necessary depth measure-
ments before the old guides are removed. The normal
fit clearance between valve stem and guide is .00087 to
.00217 inch with a maximum wear limit of .0059 inch.
To check this see FIG 1:18.
4 The valve seats should always be reconditioned after
decarbonization. It is suggested that this operation be
left to a  local  service station with valve seat cutting
equipment. The valve seat angle for both inlet and
exhaust valves is 4 5 ° ±  5'.
5 Inspect the valves for soundness or distortion and  if the
clearance between guide and stem is within the manu-
facturers wear tolerance of .0049 inch  the valve may
be cleaned using a wire brush and the seating face
ground to an angle of 45°30' ± 5'. This again should
be  left to the local service station.
Valve springs:
Thoroughly clean the valve springs of oil deposit and
inspect for cracks.  It is advisable to check the free spring
height and  if this dimension differs from the original
height, details of which are given in Technical Data, the
spring must be renewed. Any decrease in length indicates
that the spring  has weakened. 

After the  crankshaft  has been reground  it is important
that all traces of swarf are removed  by constant washing
and then drying with a non-fluffy rag.
The clearance between the main bearings and journals
must be checked before installing the crankshaft in the
engine. It should also serve as a recheck after the
crankshaft has been reground.
Measure the maximum main bearing internal
diameter and the minimum journal diameter using
accurate measuring equipment. The clearance must not
exceed .0039 inch otherwise the journals must be
reground and undersize bearings fitted.
Undersize bearings w i t h  .0394  inch stock on the
internal diameter are also supplied unmounted. They
must be press fitted in the supports, the recommended
interference fit being .00039 to  .00197 inch. After
pressing the  bearing  into the support,  a hole is drilled in
the bearing in line with the location dowel hole in the
support. The hole is finished with a suitable expanding
reamer, such as  Fiat U.0334, and the dowel pressed i n ,
noting that the hollow dowel fits in the flywheel end
support.
The next stage is to heat the assembly in an oven or
oil bath for a period of one hour at 150°C (302°F).
When the assembly has cooled to room temperature,
the bearing is reamed in a lathe to match the crankshaft
journal size.
3
Crankshaft oil seals:
Two inner spring rubber oil seals are located, one in a
special seat in the timing gear cover and the other in the
flywheel end of the crankshaft support and provide oil
tightness. These seals are shown in FIGS 1 :3 and 1 :34.
Whenever the engine is dismantled for overhaul  these
seals should  be carefully inspected for correct seating and
that the  inner seal surface is not worn and that the contact
area  is  perfect both on the crankshaft and on the fan  and
generator drive pulley hub.
Clutch shaft pilot bushing:
A self-lubricating bronze bush  is fitted  in the end of the
crankshaft as shown  in FIG 1 :34 and provides a bearing
for the  clutch shaft. Should the bush be worn use Fiat
puller A.40006/1 /2 to remove the worn bush. A new bush
should be fitted using a suitably sized drift.
1:12 Flywheel and starter ring gear
The flywheel should be inspected for wear at the clutch
driven plate contact area. It should  be flat and have a
smooth finish.
The ring gear teeth should be cheeked for damage
which if evident, the ring gear must be replaced. To facili-
tate the fitting of a  new ring gear on the flywheel, the new
ring gear should be heated in an oil bath to a temperature
of 80°C  (176°F). Using a press gently ease  the  
expanded
ring gear over the flywheel and press fully home.
1:13 The oil pump
Sedan :
A helical-spur gear type oil pump is driven  by the cam-
shaft through a front dog drive coupling. The gears are
F50025 To remove the pump from the engine proceed as
follows:Pump removal and reassembly:
Remove the engine rear  central support from the timing
gear casing. Remove the filter cover pulley and lift
away the drive  belt.
Release the  hollow screw attaching the slinger and the
mounting flange of the filter on the crankshaft. Also
release the nuts fixing the timing  gear cover to the
crankcase.
Remove the timing gear cover together with the oil
pump assembly and the pressure relief valve.
Lift out the oil pump suction scoop with the filter
screen attached from the sump.
Reassembly of the pump to the engine  is the reverse
procedure to dismantling. 1
2
3
4
5 located in a special housing in the timing gear cover and
held  in  place by a cover plate. The oil  pressure relief valve
is mounted on the drive gear shaft guide.
A pump suction scoop fitted with a filter screen is
secured  in the crankcase and  connects to a duct in the
timing gear case as s h o w n  in FIG 1 :36.
2
4
6Key t o  Fig 1 :36
Rocker shaft
Ducts, cylinder head oil drain
Oil pressure relief valve
to centrifugal filter
9
with central oil gallery
12Sump cooling air conveyor
indicator sending unitOil filler with vent valve
Line, oil delivery to rocker shaft
Level indicator rod 31
5
7Gear pump
8 Oil duct
Centrifugal oil fitter
1110
Crankshaft
Oil pump intake screen filter
13 Low oil  pressure FIG 1:36 Engine lubrication diagram 

CHAPTER 2
THE FUEL SYSTEM
2:1 Description
2 : 2 Fuel pump operating principles
2 : 3 Routine maintenance
2 : 4 Pump removal, dismantling and examination
2 : 5 Reassembly, installation and adjustment
2 : 6 Carburetter operation and adjustment,
Weber 26.1MB2 : 7 Modifications
2 : 8 Carburetter operation and adjustment,
Weber 26.OC
2 :9  Air  cleaner
2 : 1 0 B l o w - b y gases recirculation device
2:11 Fuel tank
2:12 Fault diagnosis
2:1 Description
All the new 500 models use a mechanical diaphragm
fuel feed  pump as shown in FIG 2 : 1. Four types of
carburetter are fitted depending on the model to which
the engine is installed. Each carburetter operation and
adjustment is fully described,  together with details of the
recirculation device for  blow-by gases and  o i l vapours.
2 : 2  Fuel  pump  operating principles
Refer to FIG 2 : 2. An eccentric on the rotating camshaft
actuates the operating  rocker 21  via a pushrod 25 which
depresses the diaphragm 14 and so creates a depression
in the pumping chamber located in upper body 5.  Under
atmospheric pressure, petrol passes through the pipeline
connection and inlet valve into the pumping chamber.
The return spring 15 then raises the diaphragm, expelling
the petrol through the outlet valve and  pipeline to the
carburetter float chamber.
When the float chamber is full, the pressure in the pipe-
line and pumping chamber holds the diaphragm depressed
against the tension of the return spring.2 : 3 Routine maintenance
A poor delivery of fuel to the carburetter may be due to
a fault in the fuel  pump or related lines. Periodically the
pump body screws 19  (see FIG 2 : 2) and upper cover
screw 1  should  be checked for tightness. The fuel pump
lines should be disconnected and checked for freedom of
restriction, chafing and loose connections. The fuel pump
filter should  be removed and cleaned periodically.
2:4 Pump removal, dismantling and examination
The pump is located on the carburetter side of the
engine crankcase (sedan) or under the generator at the
front of the crankcase (station wagon).
Removal:
1 Disconnect the fuel pipe from the tank to stop petrol
syphoning out of the tank and then release the fuel
inlet and outlet pipes from the  pump body.
2  Remove the t w o nuts and washers holding pump to
crankcase.
3 Carefully lift away the pump, gaskets and insulating pad
from the crankcase (see FIG 2 : 3).
F50035