1957 FIAT 500 Torque setting

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

FEELER GAUGE
Checking ring gap (ring in cylinder) FIG 1 :27
FIG 1 :28.A universal piston ring compressor should be
used to keep the rings t i g h t in their grooves. The correct
matching of the piston and connecting rod is described in
a later section of this chapter.
1 :10 Connecting rods
Checking rod bearing inserts and crankpin jour-
nals:
The big-end bearing halves are of the babbit lined thin
wall type and must not be modified in any way. Should
score marks or excessive wear be evident the bearing
inserts must be renewed. It is recommended that if the
bearing inserts are to be renewed due to wear the crank-
pins should be measured to see if regrinding is required.
Before regrinding the crankpins they should be
measured at the maximum point of wear to determine the
class of bearing undersize to be fitted after regrinding the
crankpins. Undersize bearing halves are available in the
f o l l o w i n g sizes .01, .02, .03 and .04 inch. The correct
bearing crankpin clearance is .00043 to .00240 inch and
must be checked as detailed in the following section.
Checking rod bearing insert to crankpin journal
clearance:
Before the crankshaft is installed into the engine after
overhaul the clearance must be checked to ensure that it is
within the manufacturers recommended limits. To check
the clearance proceed as follows:
1
2Lubricate the crankpin and bearing inserts and install
the connecting rod together with its bearing halves on
the crankpin. Tighten the cap nuts to a torque wrench
setting of 23.9 Ibft.
Rotate the connecting rod around the crankshaft jour-
nal several times to seat the bearing insert correctly.
Remove the bearing end cap and carefully wipe away
all traces of the lubricant.
22FIG 1 :29 Connecting rod components Piston installer A.60154
FIG 1 :28PISTON INSTALLER
A. 60154 If the clearance indicated is within the recommended FIG 1 :31.
4
Place a piece of 'Plastigage type PG-1' along the full
width of the bearing insert along the crankshaft
longitudinal axis (see FIG 1 :30) . Refit the bearing cap
and tighten the nuts to a torque wrench setting of
23.9 Ib ft. Remove the bearing cap and upon inspection
the 'Plastigage' will be found to have adhered to either
the crankpin or bearing insert and will have developed a
rectangular section. To determine the actual clearance
between the crankpin and bearing insert compare the
width of the flattened 'Plastigage' at its widest point
with the graduations on the envelope as shown in 3
PISTON RING

tolerance range of .00043 to .00240 inch or less than
.0059 inch the bearing inserts may be used again with-
out any need for regrinding. Should however the
clearance be greater than .0059 inch the inserts must be
renewed, using undersize inserts if the crankpin journals
have been reground.
It should be observed that 'Plastigage PG-1' is suitable
for measuring clearances up to .0030 inch so that if
carrying out 3 above produces no flattening of the
'Plastigage' the procedure must be repeated using
'Plastigage PR-1' which enables clearances up to
.0060 inch to be measured.
5
CRANKSHAFT
CON RODCALIBRATED STRIP
CON ROD
BEARING CAP
BEARING INSERT
FIG 1:30 'Plastigage' position for bearing insert-to-
crankpin journal clearance inspection
GRADUATION SCALE
BEARING .INSERT
CLEARANCE
READINGCALIBRATED
STRIP
CON ROD BEARING CAP
FIG 1 :31 Checking bearing insert-to-crankpin journal
clearance by comparing width of flattened 'Plastigage'
F50023
To fit a replacement bush proceed as follows:
Firmly hold the connecting rod between soft faces in a
vice in such a way that it will not bend when working
on the small-end and using a suitably sized drift, remove
the old bush.
Use Fiat tool A.60155 or a suitably sized drift and care-
fully install the new bush which must be an interference
fit of between .0011 to .0036 inch.
A small slot must be cut in the bush to correspond w i t h
the groove machined at the top of the connecting rod
so ensuring good lubrication between the bush and
piston pin. 1
2
3The small end bush must be a firm fitting in the con-
necting rod and show no signs of deep scoring, scuffing,
ovality or excessive wear.
Should it be considered necessary, the bush may be
reamed using a Fiat expanding reamer U.0307 so that the
bush internal diameter permits an oversize piston pin to be
fitted with a clearance of .00020 to .00063 inch. Little end bushing:Installation of connecting rod bearing inserts:
During reassembly of the big-end bearing inserts the
parts must be thoroughly cleaned and then to reassemble
proceed as follows:
Ensure the bearing half to connecting rod surfaces are
perfectly smooth and free of score marks. Under no
circumstances may the bearing surface be reworked.
Check that the bearing half inserts are properly seated,
with the locating lugs fitting into their slots: this is
essential to obtain
correct bearing clearance.
As the circumference of the bearing half is greater than
the seats in connecting rod and cap the bearing must be
fitted so that the projection at each end of the bearing
half is equal.
Thoroughly lubricate all parts and tighten the end cap
nuts to a torque wrench setting of 23.9 Ib ft. 1
2
3
4FIG 1:32 Connecting rod-piston assembly installation
on engine
REVOLUTION
DIRECTIONPISTON SLOT
CAMSHAFT
CONNECTING
ROD NUMBER

FIG 1:33 Checking crankshaft land-to-connecting rod
shoulder clearance
FIG 1:34 Engine f r o n t end without flywheel
Using an expanding reamer or Fiat reamer U.0307 ease
out the internal diameter of the bush to between .7874
to .7876 inch so that a standard piston may be fitted.
4
Piston-connecting rod assembly:
To assemble the piston to the connecting rod fit the
connecting rod to the piston so that the cylinder identifica-
tion number which is stamped on the connecting rod stem
and cap faces the expansion slot side in the piston as
shown in FIG 1 :32.
Lubricate the piston with engine oil, compress the
piston rings into their grooves and insert the piston con-
necting rod assembly into the cylinder barrel w i t h the
identification numbers facing to the side opposite to the
camshaft as shown in FIG 1 :32.
If one or both connecting rods have been renewed the
new connecting rod cap and body must be stamped w i t h
the cylinder identification number. The figures should be
stamped as shown in FIG 1 :32.
24
FIG 1:35 Camshaft end crankshaft supporting mem-
ber and bearing assembly, and spare main bearing
CRANKSHAFT
SUPPORTING MEMBER
(Camshaft end)
MAIN BEARING
Carefully inspect the crankshaft for minute cracks espe-
cially where there is a change in section. Should there
be any doubt always consult the official agents for
further advice.
Inspect the journals and crankpins. Should score marks
or ovality exist on the journals or crankpins they must
be reground and new undersize bearings fitted.
Undersize main bearings are obtainable in the sizes
.0079, .0157, .0236, .0314, .0394 inch ready fitted in
supports.
Undersize connecting rod bearings are obtainable in the
sizes .01, .02, .03 and .04 inch. The crank should be
reground to match the appropriate bearing undersize.
The clearance between the main bearing to journal
should be .00079 to .00256 inch and the connecting
rod bearing half to crankpin between .00043 to
.0024 inch.
2 1
The special cast iron crankshaft is hollow to allow for
the passage of lubrication oil. It is supported at its ends and
is provided with two cranks and a central counterweight.
The crankshaft plays an important part in the operation of
the lubrication system as its cavity provides a passage for
the oil flowing from the centrifugal filter.
Before inspecting the crankshaft thoroughly clean the
internal passage and drillings as well as the exterior and
then proceed as follows: 1:11 Crankshaft and main bearings Upon reassembly the connecting rod cap nuts must be
tightened to a torque wrench setting of 23.9 Ib ft.

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.

5 Using the graduated sector check that all the valve
timing angles are as detailed in Technical Data.
Readjust the valve stem to rocker arm clearance to the
correct setting.
1:16 Valve stem-to-rocker clearance adjustment
It is important that the clearance between the valve
stem and rocker is kept to the recommended figure
of .0059 inch, measured when the engine is cold.
If the clearance is excessive operating noise will occur
and if less than recommended the valves will stay open
too long which will result in damage to the valve face
and its seating.
Inspect the contacting surfaces for scoring or pitting:
if it is excessive, new parts must be fitted. Also check
the condition of the rocker-to-valve and rocker ball
head-to-pushrod contact surfaces are free from wear or
pitting. The faces must have a mirror finish.
The oilway in the rockers and shaft must be thoroughly
inspected and free from sludge, otherwise lubrication
failure will occur.
The assembly clearance between the rocker arm and
shaft should be .00063 to .00217 inch and the clearance
between the rocker shaft and the shaft support should
be .00020 to .00138 inch with a maximum wear limit of
0039 inch.
Turn the engine until the valves of one cylinder are in
balance, that is, the inlet valve opening and the exhaust
valve closing. The other cylinder will now have both valves
fully closed. Adjust the valves on this second cylinder by
loosening the locknut, and turning the
adjuster as shown in
FIG 1 : 43 to obtain the desired clearance measured with
a feeler gauge. Adjust the clearances on the other cylinder
in the same manner.
1 :17 Engine assembly (sedan — all versions)
To reassemble the engine proceed as follows:
1 Thoroughly clean and dry all the parts, ensure that all
drillings are free from dirt or sludge and place on a
clean dry surface.
2 Carefully install the cylinder-piston-connecting rod
assemblies w i t h new paper gaskets between the
cylinders and crankcase seats.
3 Refit the big-end bearing shells to the connecting
rods, ensuring that they are free from any dirt or
metallic particles. Carefully ease t h e crankshaft into
the crankcase, lubricate the main journals with clean
engine oil, place a new paper gasket between the
supporting member and the flywheel end of the
crankcase. Install the supporting member and bearing
assemblies. Secure the supporting members with the
screws and special toothed washers.
4 Locate the connecting rod big-end half onto the
crankpin journals, liberally lubricate the journals with
fresh engine oil, fit the remaining shell half, matching
bearing end cap and tighten the bearing cap nuts to a
torque wrench setting of 23.9 Ib ft.
5 Inspect the camshaft bearing bores and remove any
burrs w i t h a hand scraper wetted with oil. Carefully
slide in the camshaft ensuring the cam lobes or gear
teeth do not score the front bearing bore.
6 Fit a new timing gear cover paper gasket held in
place w i t h a little grease. Install the outer thrust ring,
F50029 inner thrust ring, shoulder washer and slide on the
camshaft drive sprocket, locking it with the Woodruff
key. Assemble the timing chain and driven sprocket,
ensuring that the timing marks on the sprocket are
indexing as shown in FIG 1 :41. Secure the driven
sprocket with six screws and lockplates and care-
fully bend down the lockplates.
7 Install the timing gear cover, the oil pump, oil pressure
relief valve and seal assembly. Secure w i t h nuts,
special toothed washers and plain washers located
in the same manner as was noted on dismantling.
Locate the oil pump suction horn and secure with the
nuts and toothed washers.
8 Install the flywheel in the same relative position to the
crankshaft as was noted on dismantling. Replace the FIG 1 : 4 3 Adjusting the rocker clearances using the
optional service tools. Refer to Technical Data for the
correct clearance on early and late engines FIG 1 :42 Graduated sector C.673 for valve gear
timing
TIMING MARK

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