1957 FIAT 500 oil filter

Drain the oil sump to ensure that the oil does not syphon
out. Thoroughly clean the area around the pump body
(see FIG 1 :37).
Remove the end cover plate by releasing the retaining
bolts and washers. Carefully ease t h e driven gear down-
wards followed by the driving gear and shaft
Clean all parts removed and blow clean using a com-
pressed air jet. Inspect the timing gear cover pump area
for cracks or distortion. Check that the inner duct for oil
delivery to the pump is clear of obstruction. If in doubt
remove the drain plug and filler cap and use a com-
pressed air j e t to clean the passage.
Check the gear teeth for damage or excessive wear,
ensure that the drive gear is firmly attached to its spindle
and that the end cover plate is not badly scored or pitted.
Fit new parts as necessary.
Reassembly is the reverse procedure to dismantling,
taking care that all parts are assembled clean and the
end cover plate seating correctly with a new gasket. 5 43 21
1:14 Lubrication, oil filter, relief valve
Description :
The engine is pressure lubricated through a gear type
pump which is incorporated in the timing gear cover and
driven from the camshaft by dogs or gears. The lubrication
circuits are shown in FIGS 1 :36 and 1 : 37.
The pump draws oil from the sump through a suction
horn fitted with a filter screen which is fixed to the crank-
case by a d u c t in t h e timing gear cover. This
supplies oil
to the pump.
Oil passes f r o m the camshaft rear seat o n t o t h e crank-
shaft rear support where it flows into an adjacent chamber.
From here the o i l flows through ducts in the crankshaft
from end to the centrifugal oil filter. The centrifugal filter,
which also acts as a pulley for the generator and blower
drive, rotates w i t h the crankshaft.
Oil from the filter enters a passage in the crankshaft,
where it lubricates the main and connecting rod bearings
and passes f r o m a special groove in the front main
bearing and ducting in the crankcase into which is
inserted the oil pressure warning sender unit, and also
the delivery pipe for oil to the overhead valve gear.
The pushrod sleeves provide the return path for the oil
from the cylinder head and delivers oil to the tappet gear
and the camshaft cams. The tappets are suitably drilled
to allow correct circulation of the oil. The tappets are
located in t w o casting cavities, one of which com-
municates w i t h the timing gear housing and the other
one to the crankshaft front drain support drain.
The oil pressure is regulated by a pressure relief valve 5
(see FIG 1 : 3 8) mounted at the rear end of t h e camshaft.
It comprises a hubbed disc which slides on a guide 6 of
the oil pump drive shaft 7. Under spring load 9 the valve
disc circumferentially closes an annular chamber which
communicates w i t h the lubrication circuit. Excessive o i l
pressure causes the disc to uncover the chamber.
Centrifugal oil filter:
The oil filter is of the centrifugal type comprising of
two flanges and an oil slinger. The filter is attached to the
rear end o f t h e c r a n k s h a f t a s s h o w n i n FIG 1 :38. The
outside diameter of the oil slinger (see FIG 1 :39) is
smaller in diameter than that of the flanges but of such a
F50027
Key to Fig 1:39 1 Drive pulley 2 Rotor hub
3 Seal ring 4 Oil slinger 5 Lockplate
6 Hub-to-crankshaft hollow screw 7, 8, 9 Pulley-to-hub
mounting screws, toothed washers and plain washers FIG 1:39 Centrifugal oil filter components Key to Fig 1 :38 Suction scoop 2 Hole in crankcase
3 Duct in timing sprocket cover 4 Timing sprocket cover
5 Oil pressure relief valve 6 Drive shaft guide and oil
pump cover 7 Oil pump driving gear shaft 8 Camshaft
9 Oil pressure relief valve spring FIG 1:38 Engine longitudinal section through oil pump

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 :44 Cylinder head h o ld-down nuts tightening
sequence. 500 Sedan
TIMING CHAIN ENDCYLINDER No. 1 CYLINDER No. 2 FLYWHEEL END
CAMSHAFT
EXPANSION SLOT C/ROD NUMBERROTATION DIRECTION
FIG 1 :45 The correct position of connecting rod-
piston assembly on engine 120.000
30
screws and together with new lockplates tighten to a
torque wrench setting of 23.1 Ib ft. Bend down the
lockplates.
9 Slide the centrifugal oil filter mounting flange, the
oil slinger and the mounting screw together with its
lockplates onto the crankshaft and tighten the screw
to a torque wrench setting of 108.5 Ib ft. Bend down
the lockplate.
10 Assemble the clutch assembly to the flywheel and
using Fiat pilot A.62023 centralize the driven plate
to the pressure plate assembly. Secure the pressure
plate assembly using screws and toothed washers.
11 Fit new oil pan cork gasket, if necessary using a little
grease to hold in position and carefully fit the oil pan
securing with screws, toothed washers and lock-
plates. Bend down the lockplates onto the screw
heads.
12 Fit the oil cooling air conveyor on the oil pan and
secure with screws and toothed washers.
13 Carefully turn the engine over and fit the centrifugal
filter mounting flange rubber seal. Fit the oil filter
cover and secure with screws together with plain and
toothed washers to a torque wrench setting of
5.8
Ib ft.
14 Ensure t h e faces of the cylinder head and cylinders
are free from dirt and oil and carefully slide the
cylinder head gasket over the studs ensuring that it
is the correct way up. Insert the tappets in the same
order to removal together with the sleeves, pushrods,
oil delivery line to the rocker arm shaft and the casing
with its seal ring.
15 Thoroughly inspect the cylinder head to ensure that
it has been correctly reassembled, carefully slide it
over the studs and secure using the four cap nuts
internally and four standard nuts and plain washers
externally. Tighten the nuts in the order as shown in
FIG 1 :44 or 1 :46 to a torque wrench setting of
23.9 Ib ft.
16 Fit the rocker arm shaft and arm assembly together
with the two supports. Tighten the supports using
screws, plain and toothed washers to a torque
wrench setting of 15.2Ibft. Adjust the tappet-to-
rocker clearance as detailed in Section 1 :16.
17 Temporarily plug the intake duct hole to ensure that
no foreign matter finds its way into the engine.
Install the spark plugs having ensured that they are
clean and correctly adjusted.
18 Reassemble the engine cowling and air
exhaust
throttle valve assembly which should be secured on
the top side using t w o nuts, t w o plain washers and
two toothed washers, on the underside with two
screws and t w o toothed washers, and centrally using
one screw and one spring washer.
19 Fit the toothed washers on the end of the spark plug
electrode and tighten the terminals together with the
special rubber boots.
20 Refit the fan, generator and ground cable assembly
and secure the crankcase, also the warmed air intake
shrouding. Finally tighten the generator to fan nuts.
21 Fit both lower exhaust silencer mounting brackets
onto the crankcase but do not tighten fully. Fit the
air conveyor and secure to the engine cowling using
six screws, six toothed washers and one nut together
with a toothed washer. Join together the t w o

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

1
14,5
7,52 9 48 35
76
FIG 2:15 Float level setting diagram Weber car-
buretter type 26.OC
7.5 = .29 inch 14.5 = .57 inch
Key to Fig 2:15 1 Carburetter cover 2 Cover gasket
3 Needle valve 4 Valve needle 5 Lug 6, 7 Arms
8 Needle ball 9 Float
Idle speed adjustment:
The idling speed is adjusted by movement of the throttle
setscrew and the mixture setscrew. The throttle screw
allows for the adjustment of the throttle opening whereas
the conical mixture setscrew has the purpose of metering
the amount of charge issuing from the idling speed pas-
sage, which will then mix with the air flowing past the
throttle which when correctly set for normal idling speed
should leave a gap between its edges and the throat walls.
This ensures a correct petrol/air ratio best suited to the
engine requirements and smooth operation.
The idling speed should always be adjusted with the
engine running and at its normal operating temperature
by first setting the throttle to its minimum opening by
turning the throttle setscrew so enabling an accurate
adjustment to be made. Then slowly turn the mixture set-
screw either in or out so as to adjust the mixture petrol/air
ratio to the most suitable for the throttle opening, this will
accomplish a fast and steady idling speed which should be
then reduced by closing the throttle opening slightly by
easing back the throttle setscrew. This adjustment should
continue until the best idling speed is obtained.
Adjustment of fuel level in float chamber:
To check and adjust the level of fuel in the carburetter
float chamber proceed as follows:
1 Check that the needle valve 3 (see FIG 2:15) is
screwed tight on its seat.
2 Keep the carburetter cover 1 upright or else the weight
of the float 9 will lower the ball 8 fitted on the needle 4.
F50043
Key to Fig 2:17 1 Filter housing 2 Spring hooks
3 Filter element 4 Cover 5 Air suction pipe, hoses
and clamps 6 Re-circulation pipe for blow-by gases and
oil vapoursFIG 2:17 Removing the air cleaner, 500F, L
2
1 3
4.
6
5
FIG 2:16 Taking out the filter element, 500, 500D AIR CLEANER ELBOW
HOSE
AIR CLEANER BODY
FILTER ELEMENT Check that with the cover held in the vertical position
and the float arm 6 in slight contact with the ball 8 of the
needle 4, the float is .2953 inch away from the cover
w i t h its gasket 2 fitted flat against the cover face.
3 Check that the float level is .5709 inch from the cover
face and if necessary bend the lug 5 to give the required
setting.
4 If the float 9 is not correctly positioned bend the float
arm 7 until the correct adjustment is obtained. Ensure
that the arm 6 is perpendicular to the needle axis and
does not show any rough spots or indentations which
might impair free movement of the needle. Check that
the float 9 moves about its pivot pin.
Every time a new float or needle valve is fitted the above
detailed adjustment operations must be completed to
ensure correct fuel levels.

FIG 2:18Diagram of blow-by gases re-circulation device
Key to Fig 2:181 Head cover 2 Blow-by gases and oil vapours breather valve 3 Oil filler cap4 Strainer
9 Air suction pipe, air cleaner to carburetter 8 Flame trap
13 Exhaust duct 12 Crankcase 7 Carburetter 6 Air cleaner
11 Filter gauze
10 Movable partition 5 PipeEngine 110 F. 000 Engine 120.000
designed to dampen the air intake noise and the carburet-
ter venturi hiss and is so located in the blower conveyor
system so that only clean dry air is drawn into the induc-
tion system.
To ensure complete protection of the engine it is
recommended that the air filter element be replaced every
6000 miles or even earlier if the vehicle is operating in
dusty conditions.
It should be noted that an oversize air cleaner may be
obtained if the vehicle is to be operated in very dusty areas.
Air cleaner—engine 110 F.000:
To remove the air cleaner element, disengage both the
spring hooks 2 as shown in FIG 2:17 and lift away the
cover 4 by turning it inwards together with the hose 5. 2 : 9 Air cleaner (sedan)
The pleated paper air cleaner element is contained in a
casing housed in a recess of one of the silencing chambers
provided in the blower conveyor as shown in FIG 2:16.
The air cleaner is connected to the carburetter by means of
a specially shaped hose. The silencing chamber is
44For full instruction refer to Section 2 :6. Carburetter cleaning:See Section 2 :6 for full check details. Throttle valve components:
Engine 110 F. 000

Air cleaner—station wagon:
A pleated paper air cleaner element is housed in a
special air intake chamber connected to the front of the
engine air cooling cowling (see FIG 4 : 2) . This chamber
will be seen located towards the rear of t h e power unit
compartment. Remove the retaining wing nut, lift off the
lid and the element can be withdrawn by lifting upwards.
2:10 Blow-by-gases recirculation device
Engine 110 F.000
All the oil vapours and blow-by-gases that are formed
in the engine crankcase are drawn to the cylinder head
cover recess 1 (see FIG 2:18). From here they travel into
the pipe 5 via a breather valve 2 which is firmly attached to
the oil filler cap 3 and the strainer 4 located in the filler
neck. The oil vapours and gases are then d r a w n back into
the duct 9 from the pipe 5 which connects the air cleaner
6 to the carburetter 7. This ensures a complete closed cir-
cuit circulation.
Engine 120.000:
From engine No. 288156 the oil vapours and blow-by-
gases instead of being exhausted to the atmosphere are
conveyed to the air cleaner and from here they are drawn
back into the combustion chambers. To ensure that an
excessive of oil vapour does not pass along the piping
with the blow-by-gases a diaphragm is fitted in the duct
in front of the breather valve 2 (see FIG 2 :18), the dia-
phragm comprising a filter gauze 11 and moveable parti-
tion 10.
It should be noted that the oil vapour strainer 4 (see
FIG 2:18) and the flame trap 8 can easily be removed
from their seating for cleaning or renewal.
2 : 1 1 Fuel tank
The fuel tank is located in the front compartment as
shown in FIG 2:19, it comprises a filler union fitted with a
cap, a fuel reserve supply indicator sender unit and a con-
nection incorporating a filter for the main fuel supply pipes.
To remove the tank proceed as follows:
1 Remove the contents of the front compartment includ-
ing the spare wheel and tool bag.
2 Disconnect the main fuel line at the sender unit and also
disconnect the cable to the fuel reserve supply indicator.
3 Remove the four screws together w i t h the clips that fix
the tank to the body and carefully lift away the fuel tank.
4 Carefully drain the contents of the tank into a clean dry
container of a suitable capacity.
Fuel tank—sedan (110 F.) and station wagon (120):
The fuel tank is arranged in the front compartment as
shown in FIG 2 :20. To remove the fuel tank proceed as
follows:
1 Remove both screws which secure the front ends of the
clamping bands to the dash panel. The screws are
shown by arrows in FIG 2 :20.
Petrol tank cleaning:
The tank must be thoroughly checked for leaks espe-
cially at the joint seams. Should a leak be found it is
F50045
advisable for a garage to attend to this as it is very dange-
rous to apply heat to a petrol tank without first taking strict
precautions and a garage will be in a better position to do
this. To clean the tank interior, remove the drain plug and
spray in a jet of air or petrol so that all sediment and dirt
deposits can be loosened. Then vigorously shake the tank.
Flush the tank w i t h petrol and blow the tank dry. Repeat
this procedure until the tank is clean. Refit the drain plug.
Whilst the petrol tank is away from the car it is advisable
to disconnect the fuel feed pipes at the pump and the
carburetter and ensure that these are clear by using an air
jet to one end of the pipe.
Key t o Fig 2 :20
Note Arrows point to fuel tank clamping band screws vent valve
indicator tank unit1 Fuel tank2 Filler cap with
3 Fuel suction pipe and reserve supply
4 Tank clamping bands
FIG 2:20 Location of the fuel tank in front compart-
ment, 500F, L FIG 2:19 Fuel tank in front compartment. The fuel
reserve supply indicator (red light) glows when fuel
amount in tank is less than .8 to 1.1 Imp galls, or 5 litre FUEL TANK
FUEL LINE TO PUMP
FUEL GAUGE CABLE

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