ignition FIAT 500 1964 1.G Workshop Manual

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

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.

FIG 1 :40 Engine detail showing lube oil passages
Key to Fig 1 :40 1 Splines in crankshaft for oil passage
to filter 2 Oil inlet into circuit from filter 3 Hole for
oil passage to main bearing
FIG 1 : 4 1 Timing marks on sprockets. On later cars the
crankshaft key way is on the underside
size that centrifugal force does not sling oil into the area
where the foreign matter is collected. The outer flange
inner face has radial vanes on its face which retain the
foreign matter and the oil is conveyed to the centre of
the filter.
The oil to be filtered issues from the side splines 1
(see FIG 1 :40) of the crankshaft and is forced by the
slinger to the periphery of the filter where it is cleaned and
returns to the centre of the filter and into the crankshaft
drilling 2. The inner flange or hub and the slinger are
secured to the crankshaft by a special hollow screw 6 as
shown in FIG 1 :39, the outer flange is attached to the
hub by six screws.
28
If the camshaft has been disconnected from the crank-
shaft for any service operation the valve gear will have to
be retimed and to do this proceed as follows:
1 Turn the crankshaft until the reference line on its
sprocket is pointing towards the camshaft as shown in
FIG 1 :41.
2 Turn the camshaft until the reference dot on its
sprocket registers w i t h the crankshaft sprocket. Leave
the shafts undisturbed and carefully mount the chain.
Should it be necessary to check the valve timing and
sprocket marks, proceed as follows:
1 Fit Fiat C.673 tool as shown in FIG 1 :42.
2 Temporarily adjust the valve stem-to-rocker arm
clearance of cylinder No. 1 at .01 77 inch for the inlet
valve and .01 50 inch for the exhaust valve (Model 500
engine) or at .01 54 inch for both valves (Model 500
sports).
3 Rotate the crankshaft and set the flywheel timing mark
at 'O' on the graduated sector. Check that the sprocket
marks are correctly lined up in this position.
If the engine is being assembled, to install the driven
gear, proceed as follows:
1 Set the timing mark on the drive sprocket towards the
centre of the camshaft.
2 Position the driven sprocket on the camshaft mounting
flange with four screw holes in line and tighten two
mounting screws only.
3 Rotate the camshaft until the driven sprocket mark
registers w i t h the reference line on the drive sprocket.
4 Remove the driven sprocket without moving the
camshaft. Install the timing chain and replace the
driven sprocket. Tighten the four screws to a torque
wrench setting of 6.5 Ib ft.
1:15 Valve timing
The oil pressure indicator sender unit is located on the
righthand side of the cylinder block and is connected to
an indicator light in the instrument cluster on the dash-
board.
The red indicator lights only when the ignition is
switched on and goes out when o i l pressure has built
up to between 8.5 and 14 Ib/sq in.
Should an accidental shortcircuit occur in the oil
pressure indicator circuit, the sender unit may be damaged
so the cause must be traced and rectified before the unit
is renewed.
Oil pressure indicator sender unit:
To ensure a reliable lubrication system there must be
no oil leaks from the gasket between the outer and inner
flanges. Every t i m e t h e engine is overhauled the filter
must be dismantled, cleaned and new gaskets fitted.
To clean the filter, remove the six screws and washers
and separate the drive pulley and hub. Carefully scrape
the inner surfaces to remove all sludge.
Upon reassembly the filter to crankshaft hollow
mounting screws must be tightened to a torque wrench
setting of 1 08.5 Ib ft. The cover to mounting flange screws
must be tightened to a torque wrench setting of 5.8 Ibft.
Cleaning and inspection:
A groove is machined on the outer flange periphery to
form a pulley for the generator and blower drive belt.

FIG 1 :48 Power plant front support cross-section
FIG 1 :49 Checking the generator and blower drive
belt tension
1 :19 Power plant mountings
The combined power and transmission unit is elastic-
ally mounted on two supports.
The front of the unit rests on a crossmember which is
secured under the car floor through two rubber block
mountings that are bolted to the gearbox casing as
shown in FIG 1 :48. The position of the rubber blocks
on the crossmember is adjustable so that the assembly
can be correctly aligned.
W i t h t h e rear of the unit the engine crankcase is sprung
to the b o d y rear crossmember through an articulated
swinging arm that compresses a coil spring as shown in
FIGS 1 :47 and 1 :49. A rubber bump pad is mounted
inside the spring to give a progressive action.
Whenever the power and transmission unit is being
serviced the condition of the mountings should be
checked and any worn or damaged parts renewed.
1 :20 Adjustment of generator and fan drive belt
The centrifugal oil filter cover/pulley on the crankshaft
transmits the drive through a V-belt to the generator and
centrifugal fan pulley.
32
(b) Engine stalls
1 Check 1, 2, 3, 4, 10, 1 1 , 12, 13, 14 and 15 in (a)
2 Sparking plugs defective or gaps incorrect
3 Retarded ignition 1 Defective coil
2 Faulty distributor capacitor (condenser)
3 Dirty, pitted or incorrectly set contact breaker points
4 Ignition wires loose or insulation faulty
5 Water on sparking plug leads
6 Corrosion of battery terminals or battery discharged
7 Faulty or jammed starter
8 Sparking plug leads wrongly connected
9 Vapour lock in fuel pipes
10 Defective fuel pump
11 Overchoking
12 Underchoking
13 Blocked petrol filter or carburetter jets
14 Leaking valves
15 Sticking valves
16 Valve timing incorrect
17 Ignition timing incorrect
(a) Engine will not start 1 :22 Fault diagnosis
Since its introduction the Fiat new 5 0 0 model has
been continually developed. The main modifications that
have been made are as follows:
1 Heating system safety device
2 Recirculation device for the blow-by gases
3 Cylinder head modified to incorporate item 1
4 Double valve springs fitted
5 Cylinder barrels modified to incorporate item 1
6 Flywheel modified to incorporate new type diaphragm
spring clutch mounting
7 Larger air cleaner container.
Details of these modifications are to be found in the
relevant sections if they necessitate a change in service
overhaul procedure. Other information is to be found in
Technical Data.
1 :21 Modifications
When the V-belt has been correctly adjusted the belt
should sag 13/32 inch under a hand pressure of about 22 lb
as shown in FIG 1 : 4 9.
Should the belt be too slack the generator and
centrifugal fan will not operate at the correct speed
causing overheating and a discharged battery. Also the
belt will slip causing rapid wear of the belt. Conversely
if the belt is too tight excessive loading will be placed
on the generator bearings causing excessive bearing
wear and noisy operation.
To adjust the belt tension proceed as follows:
1 Remove the three nuts ' B ' (see FIG 1 :49) on the
generator pulley and this will split the pulley into two
parts between which are spacer rings.
2 The tension of the belt is increased or decreased by
either reducing or increasing the number of spacers.
3 Place the spacer rings removed from between the
pulley halves on the pulley outer face so that the rings
may be re-inserted when fitting a new belt.
4 Tighten the three nuts to a torque wrench setting of
14.5
lb ft.
Key to Fig 1 :49 A Normal give-in: about 13/32 inch under
a 22 Ib pressure B Nuts securing the pulley halves with
spacer rings

3:1
3:2
3:3
3:4
3:5Description
Operation
Routine maintenance
Ignition faults
Removing and dismantling distributor (sedan
and sports)
CHAPTER 3
THE IGNITION SYSTEM
3:6
3:7
3:8
3:9
3:10
Removing and dismantling
(station wagon)
Timing the ignition
Sparking plugs
The distributor drive spindle
Fault diagnosisdistributor
3 :1 Description
The ignition system fitted to all the models covered by
this manual consists of an ignition coil, ignition distributor
fitted with contact breaker points, a centrifugal automatic
advance system, condenser, low- and high-tension
wiring, spark plugs and a power supply provided by a
generator and battery. The wiring diagram is shown in
FIG 3 : 1
1 The low-tension circuit which is sometimes called the
primary circuit includes the power supply, contact
breaker points, condenser and ignition coil primary
winding.
2 The high-tension circuit which is sometimes called the
secondary circuit includes the ignition coil secondary
winding, distributor rotor, distributor cap with terminals
and the central brush, high-tension cables and the spark
plugs.
3 : 2 Operation
The contact breaker unit in the distributor interrupts
the primary circuit by the points opening. The sudden stop
in the flow of current in the primary winding, does not cause
arcing at the contact breaker points because it discharges
into the condenser connected in parallel w i t h the contact
F50047
breaker points. With the sudden collapse of the primary
circuit, the intensity of the magnetic field drops causing
an induced high-tension current in the ignition coil
secondary winding. The high EMF is distributed to the
sparking plugs by the ignition distributor rotor.
The automatic advance mechanism comprises a plate
carrying t w o weights which are symmetrically pivoted on
the plate at one end. Also attached to the weights at
opposite ends to the pivots is the cam carrier shaft with
special tension return springs. Under the action of centri-
fugal force as the rotational speed increases, the weights
move outwards causing the cam carrier shaft to move
angularly compared to the distributor drive shaft thus
causing advancement of the ignition timing.
The contact breaker assembly comprises the cam on the
drive shaft and t w o contact points, one of which is
stationary while the other is under the influence of the
cam, the action of which is transmitted by a rubbing block.
The cam has t w o lobes to control the opening and closing
of contact points. The stationary contact point is mounted
on an adjustable support to enable the contact breaker
point gap to be adjusted.
The HT current reaches the distributor cap central
terminal, from the ignition coil and is distributed to each
of the spark plugs at the correct time by the rotor arm.

FIG 3 : 1 Ignition system wiring diagram
BATTERY
SWITCHBREAKER COIL
SPARK PLUG
CONDENSER
FIG 3 : 2 Ignition distributor in place on engine with
cap lifted offCURRENT CONTACT
TO SPARK PLUG
BREAKER A R M
STATIONARY
CONTACT
CARRIER
ADJUSTING
SCREW
CONTACT POINTS HIGH TENSION)
CARBON CONTACT
3 : 3 Routine maintenance
Refer to FIG 3: 2 and remove the distributor cap and lift
off the rotor arm. Lubricate the cam spindle felt pad using
Fiat VS oil. There is provision for the oil to make its way
downwards. Squirt a few drops of oil into the distributor
shaft lubrication fitting, the location being shown in FIG
3:3 Smear a little grease on the cam and a small drop of
oil to the contact breaker point pivot.
Adjusting the contact breaker points:
Refer to FIG 3 : 2 and slacken the stationary contact
carrier adjusting screw. Slowly rotate the engine until one
one of the t w o cams has opened the points to the fullest
48
extent so that the gap is measured at the position of the
maximum opening. Reset the gap to a correct clearance of
.0185 to .0209 inch and tighten the contact carrier screw.
Cleaning the contact points:
If the contact points are dirty or pitted they must be
cleaned by polishing them with a fine carborundum stone
taking very great care to ensure that the contact faces are
flat and square. Afterwards wipe away all dust with a cloth
moistened in petrol. The contacts may be removed from
the distributor body to assist refacing and cleaning refer-
ring to Section 3:5. If the moving contact is removed
from its pivot, check that its operation is not sluggish. If it is
tight, polish the pivot pin with a strip of fine emery cloth,
clean off all dust and apply a tiny spot of oil to the top of
the pivot pin. If a spring testing gauge is available the
contact breaker spring should have a tension of 16.8± 1.8
oz. measured at the points.
3 :4 Ignition faults
If the engine runs unevenly set it to idle at a fast speed.
Taking care not to touch any metal part of the sparking
plug leads, pull up the insulator sleeve and short each
plug in turn, using a screwdriver with an insulated handle.
Connect the screwdriver blade between the plug top and
the cylinder head. Shorting a plug which is firing properly
will make the engine uneven running more pronounced.
Shorting a plug in a cylinder which is not firing will make
no difference.
Having located the
faulty cylinder, stop the engine and
remove the plug lead. Start the engine and hold the lead
carefully to avoid shocks so that the metal end is about
3/16 inch away from the cylinder head. A strong regular
spark shows that the fault might be with the sparking plug.
Remove and clean it according to the instructions in
Section 3 :8. Alternatively substitute it with a new plug.
If the spark is weak and irregular, check that the lead is
not perished or cracked. If it appears to be defective,
renew it and try another test. If there is no improvement,
remove the distributor cap and wipe the inside clean and
dry. Check the carbon brush located as shown in FIG 3 : 2 .
It should protrude from the cap moulding and be free to
move against the pressure of the internal spring. Examine
the surface inside the cap for signs of 'tracking' which can
be seen as a thin black line between the electrodes or to
some metal part in contact with the cap. This is caused by
sparking, and the only cure is to fit a new cap.
Testing the low-tension circuit:
Before carrying out electrical tests, confirm that the
contact breaker points are clean and correctly set, then
proceed as follows:
1 Disconnect the black low-tension cable from the
ignition coil and from the side of the distributor.
Connect a test lamp between the t w o terminals. Turn
the engine over slowly. If the lamp lights when the
contacts close and goes out when they open, the
low-tension circuit is in order. If the lamp fails to light
the contacts are dirty or there is a break or loose con-
nection in the low-tension wiring.
2 If the fault lies in the
low-tension circuit, switch on
the ignition and turn the crankshaft until the contact
breaker points are fully open. Refer to the wiring
diagram in Technical Data and check the circuit with

a n 0—20 v o ltmeter. If the circuit is in order the meter
should read approximately 12-volts.
3 Battery to fuse box terminal 30. Connect the volt-
meter between the terminal 30 and earth. No reading
indicates a faulty cable or loose connection.
4 Fuse box. Connect the voltmeter between the other
auxiliary terminal 30 and earth. No reading indicates a
broken or loose connection.
5 Fuse box auxiliary terminal 30 to terminal
number 30 on ignition switch. Connect the meter
between terminal number 30 on the ignition switch
and earth. No reading indicates a damaged cable or
loose connection.
6 Ignition switch. Connect the meter between termi-
nal 15/54 and earth. Switch onto the ignition position,
when no reading indicates a fault in the switch.
7 Ignition switch to low-tension cable connection
on the coil (blue cable). Connect the meter
between ignition coil terminal (blue cable) and earth.
No reading indicates a damaged cable or loose con-
nection.
8 Ignition coil. Disconnect the black low-tension cable
connecting the coil to the distributor side terminal at
the coil and connect the meter between this terminal
and earth. No reading indicates a fault in the primary
winding of the coil and a replacement coil must be
fitted. If the reading is correct remake the connections
to the coil.
9 Ignition coil to distributor. Disconnect the thin
black low-tension cable at the side of the distributor
and connect the meter between the end of this cable
and earth. No reading indicates a damaged cable or
loose connections.
10 Contact breaker and capacitor. Connect the
meter across the contact breaker points. No reading
indicates a faulty capacitor.
Capacitor:
The best method of testing a capacitor (condenser) is
by substitution. Disconnect the original capacitor and
connect a new one between the low-tension terminal on
the side of the distributor and earth.
If a new capacitor is needed, fit a new one complete
w i t h bracket, but if necessary unsolder the original bracket
and solder it onto the new capacitor using as little heat as
possible. Capacitor capacity is .15-.20 microfarads.
3 : 5 Removing and dismantling distributor (sedan
and sports)
To remove the distributor proceed as follows:
1 Rotate the engine slowly until the distributor rotor arm
is opposite the brass segment in the distributor cap
connected to No. 1 plug lead. This will provide a datum
for replacement.
2 Disconnect the cable from the low-tension terminal on
the side of the distributor body. Mark position of distri-
butor on support. Release the distributor retaining nut
and washer from the underside of the top flange of the
distributor support and carefully lift away the dis-
tributor.
3 Pull off the rotor arm. Remove the insulated terminal
assembly from the side of distributor body. Release the
contact breaker carrier plate retaining screws and con-
denser flange screw from the outside of the distributor
F50049 body. Carefully lift out the contact breaker plate
assembly.
4 Before further dismantling note the relative positions of
the driving dog and the rotor arm driving slot at the top
of the distributor cam spindle. The driving dog is offset
and can only engage its driving spindle in one position.
Then when the cam assembly is fitted to the centrifugal
weights during reassembly the timing is not 180 deg.
out.
5 Take out the cam lubrication felt pad recessed in the
rotor arm housing on the end of the cam spindle.
Remove the retaining screw, carefully disengage the
springs and lift out the cam spindle. It should be noted
that there is a small retaining ball and spring located in a
drilling nearly at the top of the drive shaft spindle.
Carefully lift away the weights.
6 Thoroughly clean all parts and inspect for excessive
wear. The distributor cap must not be cracked or show
signs of tracking. The cap terminals, rotor and contact
breaker points can be cleaned with a very fine file.
Emerypaper must not be used. If the clearance between
the rotor and distributor cap segments exceeds .0118
inch both the rotor and distributor cap must be replaced.
Inspect the contact breaker arm rubbing block for exces-
sive wear and also the points for wear so that if the gap
exceeds the last setting limit of .0209 inch and adjust-
ment through the stationary contact carrier screw is no
longer possible (see FIG 3 : 2) , the contact breaker set
must be renewed.
If the distributor drive shaft side or vertical movement is
excessive the distributor must be renewed.
Weak centri-
fugal weight springs or damaged weights must be
renewed using original Fiat spares otherwise the auto-
matic ignition advance characteristics could be altered.
FIG 3 : 3 Ignition distributor in place on engine SPARK PLUG CABLES
IGNITION COIL CABLE!
DISTRIBUTOR CAP
DISTRIBUTOR BODY
GROUND CABLE
CONDENSER
DISTRIBUTOR SHAFT
LUBRICATION FITTING
DISTRIBUTORSUPPORT-TO--CRANKCASE NUT
[MOUNTING SCREWDISTRIBUTOR
DISTRIBUTOR SUPPORT

FIG 3 : 4 Use of fixture Ap.5030/1 to check ignition
timing
Reassembly is the reverse procedure to dismantling but
the following points should be noted:
1 Lubricate the parts of the centrifugal advance mecha-
nism, the drive spindle and the part of the shaft which
accepts the cam w i t h Fiat VS oil.
2 Ensure that upon reassembly the slot in the rotor arm
housing matches the distributor driving dog. Lubricate
the felt pad in the rotor arm housing.
3 Fit the distributor back onto its support gently rotating
the rotor arm so that the drive dog engages w i t h the
drive shaft mating flange. Provided the crankshaft has
not been turned the rotor arm should finish up pointing
to No. 1 cylinder segment in the distributor cap. Tighten
the distributor retaining nut, refit the distributor cap and
leads to the spark plugs and the LT lead to distributor
body terminal.
4 Add a few drops of oil to the distributor shaft lubrication
fitting (see FIG 3:3).
3 : 6 Removing and dismantling distributor
(station wagon)
The distributor is located towards the top rear of t h e
engine and is bolted direct onto the crankcase rear cover as
shown in FIG 1 : 2 . It is driven direct by a gear in mesh w i t h
a corresponding gear on the camshaft. The basic design of
the distributor is the same as that for the sedan and sports
engine, except that the distributor cap has been redesigned,
there is a gear instead of the dog
drive and no distributor
support. To remove and dismantle the distributor proceed
as previously described taking great care about marking
the location of the distributor to rear cover and rotating
the engine until No. 1 cylinder is on compression. This will
ensure that reassembly is straightforward without loss of
ignition timing.
503:7 Timing the ignition
It is necessary to retime the ignition should the distribu-
tor shaft or camshaft have been removed. To retime the
ignition proceed as follows:
1 On the timing sprocket cover fit Fiat tool AP.5030/1 as
shown in FIG 3 : 4. Ensure No. 1 cylinder is on the
compression stroke with both valves closed. Rotate the
crankshaft until the mark on the centrifugal filter cover
lines up w i t h the 10° mark on the fixture. This setting
corresponds to a 10° static advance BTDC.
2 Check t h a t the points gap is correctly set between
.018 and .020 inch. Turn the distributor shaft until the
rotor points in the direction of No. 1 segment in the
cap and the points are just opening.
3 Without disturbing the distributor shaft, insert the lower
coupling on its toothed end, install the support and
tighten the locknut. Secure the distributor to the sup-
port using the mounting screw.
To check that the distributor is properly timed to the
engine and the centrifugal automatic advance is operating
correctly giving a
total advance of 18° to 28° respectively
proceed as follows:
1 Connect Fiat timing tester AP.5030 with a 220-volt-
single-phase power outlet fitted with a good earth
connection. It is important that the tester is earthed
before it is allowed to operate. Also ensure that the
tester earth terminal is connected to a bare metal part
of the vehicle.
2 Remove No. 1 spark plug lead, insert the strobe light
adapter and reconnect the spark plug lead. Using a
piece of white chalk mark the TDC position on the
centrifugal filter cover.
3 Start the engine and aim the strobe light beam towards
the chalk mark drawn on the centrifugal filter cover.
With the engine running slowly the mark on the centri-
fugal cover must correspond wi th the first white line
on the fixture (10°). Slowly increase the speed of the
engine so operating the automatic advance and the
chalk mark should move counterclockwise until at
maximum speed it reaches the second white mark on
the fixture.
It should be noted that the ignition timing for the model
500 sports engine the static advance is 10°, an automatic
advance of 12° giving a total advance at maximum engine
speed of 2 2 ° .
Should Fiat fixture AP.5030/1 not be available the
advance position may be set as follows:
1 Turn over the
engine until No. 1 piston is on the com-
pression stroke w i t h both valves closed.
2 Rotate the crankshaft clockwise until the reference
mark cast on the centrifugal filter cover is set .5118 to
.5512 inch ahead of the arrow cast on the timing
sprocket cover. This will give a static advance setting
of 10° BTDC.
3 Proceed as directed for ignition distributor timing and
mounting described earlier in this section.
3 : 8 Sparking plugs
The sparking plugs must be regularly inspected, cleaned
and the electrode gap adjusted to a gap of .019 to .023
inch.
The inspection of the deposits on the electrodes is par-
ticularly useful because the colour and type of deposit

indicates the condition inside the combustion chamber
and may be used as a guide to engine tuning.
Before the spark plugs are removed b l o w away any
loose dirt from the plug recesses using a compressed air
jet or tyre pump. Store the plugs in the order of removal
ready for inspection.
Examine the gaskets and if they are about half their
thickness they may be used again otherwise they must be
replaced.
Inspect the electrode end of the plugs and note the
type and colour of the deposit. Normally it should be
powdery and range from b r o w n to a greyish tan in colour.
There will also be slight wear of the electrodes and the
general effect described is one which comes from mixed
periods of high-speed and low-speed driving. Cleaning
and resetting the gap is all that will be necessary.
If the deposits are white or yellowish they indicate long
periods of constant-speed driving or much low-speed
city driving. Again, the treatment is straightforward.
Dry, black, fluffy deposits are usually the result of
running with too rich a mixture. Incomplete combustion
of the petrol air charge may also be a cause and this might
be traced to a defect in the ignition system or excessive
idling.
Overheated sparking plugs have a white blistered look
about the centre electrode and the side electrode may be
badly eroded. This may be caused by poor cooling, wrong
ignition timing or sustained high speeds under heavy load.
To clean the sparking plugs effectively they should be
cleaned using an abrasive blasting machine and tested
under pressure once the electrodes have been reset. File
these until they are clean, bright and the faces parallel and
set the gap to .019 to .023 inch. Do not try to bend the
centre electrode.
Before replacing the plugs use a wire brush to clean the
threads taking care that the electrodes are not touched.
Thoroughly clean the spark plug in petrol, and dry using a
compressed air jet or a tyre pump. If difficulty is found in
screwing the plugs into the cylinder head by hand run a
tap d o w n the threads to clear away any carbon. If a tap is
not available use an old sparking plug with crosscuts d o w nthe threads. Finally tighten the plugs to a torque wrench
setting of 18 to 21 Ib ft.
Sparking plug leads:
The spark plug leads and the lead from the coil to the
distributor cap must be regularly checked for cracking of
the insulation and also correct seating in the distributor
cap and coil top. It is recommended that silicone grease is
smeared around the sockets before the leads are replaced
to ensure no moisture may enter causing difficult starting.
3 : 9 The distributor driving spindle (sedan and
sports engine)
If for any reason, the driving spindle has been removed
from its housing in the crankcase, it must be correctly
meshed w i t h the camshaft gear otherwise it
will be impos-
sible to set the ignition timing.
3:10 Fault diagnosis
(a) Engine w i l l not fire
1 Battery discharged
2 Distributor contact points dirty, pitted or maladjusted
3 Distributor cap dirty, cracked or tracking
4 Carbon brush inside distributor cap not touching rotor
5 Faulty cable or loose connection in low-tension circuit
6 Distributor rotor arm cracked
7 Faulty coil
8 Broken contact breaker spring
9 Contact points stuck open
(b) Engine misfires
1 Check 2, 3, 4, and 7 in (a)
2 Weak contact breaker spring
3 High-tension plug and coil leads cracked or perished
4 Sparking plug(s) loose
5 Sparking plug insulation cracked
6 Sparking plug gap incorrectly set
7 Ignition timing too far advanced