1967 FIAT 500 Tappet

FIG 1:1 Left side view of the power plant to suit
500 Sedan
10
FIG 1:2 Right side rear three-quarter view of the power plant for 500 Station Wagon Mounted on the top of the cylinder head is the overhead
valve rocker mechanism that is operated by a chain driven
camshaft through tappets and vertical pushrods.
The carburetter is of the downdraft type fitted with a
starting device that is controlled by a lever on the central
floor tunnel. A pleated paper element air cleaner and
silencer is fitted to the carburetter air intake. A mechanical
diaphragm type fuel pump operated from the camshaft by
a pushrod, supplies petrol to the carburetter from a fuel
tank located at the front of the vehicle.
Engine lubrication is provided by a gear pump driven
from the camshaft and mounted within the timing cover
drawing oil from the engine sump. The oil is cleaned by a
centrifugal filter situated at the rear end of t h e crankshaft
and pressure is controlled by a valve mounted on the
pump body. Crankcase ventilation is provided for through
a rubber hose connected to the top of the rocker cover.
The engine is cooled by air from a centrifugal blower
mounted on the generator shaft and housed in a specially
designed cowling conveying air to and around the engine.
The air temperature is governed by a special thermostat
fitted in the engine cowling.

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

Cylinder head installation:
To refit the cylinder head proceed as follows:
Place a new cylinder head joint on the cleaned faces of
the cylinder barrels. Insert the rocker pushrod and
lubrication pipe sleeves together with the relevant
gaskets and rings.
Fit the washers and nuts to the studs and tighten to
fingertight.
Tighten the nuts in the order shown in FIG 1 :44 and
FIG 1 :46 to a torque wrench setting of 18.1 Ibft. Reset
the torque wrench to a new setting of 23.9 Ibft and
tighten the nuts once more in the recommended order.
Replace the pushrods in the correct order.
Refit the rocker shaft ensuring correct location of the
lubrication tube to the rocker shaft and replace the
plain and lockwashers. Tighten the nuts to a torque
wrench setting of 15.2 Ibft. Reset the tappet to rocker
clearance adjustment.
Connect the t w o exhaust side manifolds to the cylinder
head. Using new gasket refit the spark plugs and HT
cables. Replace the rocker cover fitted with a new cork
gasket and blower conveyor to the cylinder head
securing screws. Refit the carburetter and reconnect its
fuel line and controls. Refit the air cleaner and elbow
and connect the rocker cover breather pipe (if fitted).
1
2
3
4
5
1 :7 Timing gear overhaul
Camshaft:
The cast iron camshaft is located in the crankcase and is
supported at either end in sets machined directly in the
crankcase. No bushes are used. The camshaft is driven by
a chain from the crankshaft at half engine speed and
operates the overhead valves through tappets, pushrods
and rockers (see
FIG 1 :20).During engine overhaul the camshaft journals and cam
faces should be free of score marks or signs of seizure and
have a bright mirror finish.
The distributor drive gear should be inspected for tooth
wear which if excessive means that the camshaft must be
replaced.
Tappets:
The tappets should be inspected for signs of seizure or
excessive wear. The end surface that is in contact with the
camshaft should be smooth without signs of excessive
wear. Any slight scratches or indentations may be
removed using a very fine oil stone.
Pushrods and sleeves:
The pushrods operate in special axially resilient sleeves
that are compressed on assembly between the cylinder
head and the crankcase. It is through these sleeves that
the engine sump is vented also through which the oil
returning from the cylinder head passes.
Two rubber O-ring seals are fitted to each sleeve to
ensure an oil t i g h t seal between the cylinder head and
crankcase. The sleeves should be checked for distortion
and exact equal length and when refitting new seals must
always be fitted.
The pushrods should be checked for straightness and
the t w o ends that contact the rocker setscrew and the
F50019
The crankcase is an aluminium casting suitably ribbed
to ensure correct air cooling. The main bearing and cam-
shaft bearing bores are machined as also are the tappet 1 :8 Crankcase and cylinders During valve gear overhauls the clearance between the
rocker shaft bore and the rocker must be checked. The
maximum permissable wear between these t w o parts is
.0059 inch. It is recommended that the part which is most
worn be renewed, or in extreme cases both parts. Rocker and rocker shaft: tappet seat must not show any signs of roughness or
excessive wear. 3 Oil shield (for intake valves only) 4 Snap ring
5 Rocker 6 Upper spring cup 7 Valve spring
8 Lower spring cup 9 Pushrod 10 Tappet
11 Oil seal ring 12 Pushrod sleeve 13 Seal ring 1 Intake valve 2 Upper cup lock Key t o Fiq
1 :20 FIG 1:20 Valve, pushrod and tappet assembly FIG 1:19 Camshaft. The arrow points to the lube oil
outlet port

Insert a .0079 ± .00197 inch thick oil paper gasket
between the crankcase and cylinder bottom face and a
.0236 to .0275 inch thick graphitized asbestos gasket
between the cylinder and cylinder head. The compression
of the gaskets on assembly will eliminate any very small
differences between the t w o mating surfaces.
Inspection of tappet seats:
The tappet seats should be checked for scoring and
correct clearance which must not exceed .00315 inch.
Should the clearance be greater than the maximum
specified the seating may be reamed to oversize dimen-
sions as detailed in Technical Data. Tappets are avail-
able in .00197 and .00394 inch diameter oversize.
1 :9 Piston assembly
Inspection:
Before inspection the pistons must be thoroughly
cleaned and the ring grooves and piston head decarbo-
nized. Check for deep score marks and signs of distortion
or fracture especially around the skirt and piston pin areas.
Using a feeler gauge ensure that the piston clearances in
the bore do not exceed a maximum of .0059 inch for the
Model 500 engine and .0079 inch for the Model 500
sports engine (see FIG 1 :25) . The measurements should
be taken at the bottom of the skirt and square to the piston
pin axis.
Should the clearance be greater than the maximum
permissible, the cylinders may be rebored and oversize
pistons fitted to m
atch them. Pistons are supplied in the
following oversizes, .0079, .0157 and .0236 inch. It
should be noted that oversize pistons and rings are not
available for the Model 500 sports engine so if the piston
to cylinder wall clearance is greater than the permissible
maximum limit the cylinder and piston assembly must be
renewed.
The piston ring to groove clearance must be checked as
shown in FIG 1 :26 and the ring gap when fitted as in
FIG 1 : 2 7. In both cases the readings should be
compared with the piston data. Piston rings are available
in the same oversize classes as the pistons. When
installing piston rings the gap should be placed opposite to
the piston expansion stops. Ensure that the ring gaps are
scattered and not in a line.
FIG 1:24 Checking cylinder head mating face f o r level
Out-of-true should not exceed .00315 i n c h
F50021
The installation of the piston and connecting rod should
be carried out on a clean workbench as shown in Reassembly of piston: Check that the f i t between the piston pin and boss is a
pinch fit. If excessive clearance is found the boss may be
reamed and a .0079 inch diameter oversize piston pin
fitted. The pin to bore pinch fit must be between .0000 to
.0039 inch. At all times the pins should be installed only
after the piston has been heated in hot water to a tempe-
rature of 80°C. Upon reassembly of the piston to the
engine the expansion slot must be placed facing the cam-
shaft.FIG 1 :26 Checking piston ring-to-land clearance FEELER GAUGE C.316
FIG 1:25 Using feeler gauge C.316 to check piston-to-
cylinder wall clearance

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