1983 FIAT UNO chapter 13

17Screw in the camshaft front bearing
lockscrew (photo).
Oil pump
18Refit the oil pump as described in Sec-
tion 10.
Timing chain and sprockets
19Fit the timing chain and sprockets as
described in Section 6. Fit the Woodruff key
to the crankshaft nose.
20Using a new gasket, fit the timing chain
cover, but leave the bolts finger tight (photo).
21Apply grease to the lips of the timing
cover oil seal and then push the crankshaft
pulley into position.
22Move the timing cover if necessary so that
the pulley hub is centralised in the oil seal and
then tighten the cover bolts.
23Screw on the crankshaft pulley nut and
tighten to the specified torque (photo).
Piston/connecting rods
24Fit these as described in Section 9.
Sump pan
25Fit the sump pan as described in Sec-
tion 8.
Cylinder head
26Stand the engine upright and fit the
cylinder head as described in Section 7.
27Insert the pushrods in their original fitted
order.
28With the rocker arm adjuster screws fully
unscrewed, locate the rocker gear and screw
on the fixing nuts.
29Adjust the valve clearances as described
in Section 5.
30Locate a new gasket in position and fit the
rocker cover (photo).
31Screw on a new oil filter (Section 2).
21 Engine- refitting ancillary
components
1Refer to Chapter 5 and refit the clutch,
making sure to centralise the driven plate.
2Fit the coolant pump as described in
Chapter 2. Fit the thermostat housing if it was
removed noting the air cleaner mounting
bracket on the housing studs.
3Fit the alternator and drivebelt as described
in Chapter 9.
4Refer to Chapter 3 and fit the exhaust
manifold and hot air collector, the carburettor
and spacer and the fuel pump.
5Fit the distributor as described in Chapter
4. Fit the oil dipstick guide tube (photos).
22 Engine/transmission-
reconnection
1
1Support the weight of the transmission and
offer it squarely to the engine. The splined
input shaft should pass easily through the hub
of the driven plate, provided the plate has
been centralised as described in Chapter 5. It
may be necessary to align the splines with the
hub grooves, in which case have an assistant
turn the crankshaft pulley nut. The alignment
dowels will make the connection stiff, so
drawing the engine and transmission together
with two connecting bolts will ease it.
2Once the engine and transmission are fully
engaged, insert and tighten all the connecting
bolts. Locate the lifting eyes.
3Bolt on the flywheel housing cover plate
and the mounting brackets.
4Bolt on the starter motor.
23 Engine/transmission-
refitting
3
1The refitting operations are reversals of
those described in Section 13.
2Observe the following special points.
3Tighten the engine mounting and front
suspension (disconnected) bolts to the
specified torque when the hoist has been
1•22 903 cc engine
21.5B Dipstick guide tube support21.5A Dipstick guide tube20.30 Rocker cover nut and thrust plate
20.23 Tightening crankshaft pulley nut20.20 Timing cover20.17 Camshaft front bearing lockscrew
Hold the crankshaft against
rotation either by jamming
the starter ring gear or by
placing a block of wood
between a crankshaft web and the
inside of the crankcase.

removed and the weight of the car is again on
its roadwheels.
4Fill the cooling system.
5Fill the engine with oil.
6Replenish lost transmission oil.
7Reconnect the battery.
8Adjust the clutch pedal as described in
Chapter 5.
24 Engine- initial start-up after
overhaul or major repair
4
1Make sure that the battery is fully charged
and that all lubricants, coolant and fuel are
replenished.
2If the fuel system has been dismantled it will
require several revolutions of the engine on
the starter motor to pump the petrol up to the
carburettor.
3Turn the carburettor throttle speed screwthrough one complete turn to increase the idle
speed in order to offset the initial stiffness of
new engine internal components.
4As soon as the engine fires and runs, keep
it going at a fast idle speed and bring it up to
normal working temperature.
5As the engine warms up there will be odd
smells and some smoke from parts getting
hot and burning off oil deposits. The signs to
look for are leaks of water or oil which will be
obvious.
6Check also the exhaust pipe and manifold
connections as these do not always “find”
their exact gas tight position until the warmth
and vibration have acted on them and it is
almost certain that they will need tightening
further. This should be done, of course, with
the engine stopped.
7When normal running temperature has
been reached, adjust the engine idle speed as
described in Chapter 3.
8Stop the engine and wait a few minutes tosee if any lubricant or coolant is dripping out
when the engine is stationary.
9Road test the car to check that the timing is
correct and that the engine is giving the
necessary smoothness and power. Do not
race the engine - if new bearings and/or
pistons have been fitted it should be treated
as a new engine and run in at a reduced
speed for the first 500 km (300 miles).
10After the first 1500 km (900 miles) the
cylinder head bolts must be re-torqued in the
following way (engine cold).
11Remove the air cleaner and rocker cover.
Unscrew the first bolt (Fig. 1.7) through a
quarter turn and then tighten it to final stage 2
torque (see Specifications).
12Repeat on the remaining bolts, one at a
time.
13Check and adjust the valve clearances
(Section 5).
14Refit the rocker cover and air cleaner.
903 cc engine 1•23
26.4 Shim engraved mark26.2 Removing a shim from a cam follower25.4 Checking a valve clearance
1
Part 3: 1116 cc and 1301 cc engines
25 Valve clearances- checking
2
This should only be required if the valves
have been renewed or ground in, or at high
mileages when noise or poor engine
performance indicates that a check is
necessary.
It is important that each valve clearance is
set correct otherwise the timing will be
wrong and engine performance poor. If there
is no clearance at all, the valve and its seat
will soon burn. Always set the clearances
with the engine cold.
1Remove the camshaft cover. Jack-up a
front wheel and engage top gear so that by
turning the wheel, the crankshaft can be
rotated.
2Each valve clearance must be checked
when the high point of the cam is pointing
directly upward away from the cam follower.
3Check the clearances in the firing order
1-3-4-2, No. 1 cylinder being at the timing
belt end of the engine. This will minimise the
amount of crankshaft rotation required.4Insert the appropriate feeler blade
between the heel of the cam and the cam
follower shim of the first valve. If necessary
alter the thickness of the feeler blade until it
is a stiff, sliding fit. Record the thickness,
which will, of course, represent the valve
clearance for this particular valve (photo).
5Turn the crankshaft, check the second
valve clearance and record it.
6Repeat the operations on all the remaining
valves, recording their respective clearances.
7Remember that the clearance for inlet and
exhaust valves differs - see Specifications.
Counting from the timing cover end of the
engine, the valve sequence is:
Inlet 2-3-6-7
Exhaust 1-4-5-8
26 Valve clearances-
adjustment
3
1Check the valve clearances (Section 25).
2Clearances which are incorrect will mean
the particular shim will have to be changed.
To remove the shim, turn the crankshaft untilthe high point of the cam is pointing directly
upward. The cam follower will now have to
be depressed so that the shim can be
extracted. Special tools (A60642 and
A87001) are available from your Fiat dealer to
do the job, otherwise you will have to make
up a forked lever to locate on the rim of the
cam follower. This must allow room for the
shim to be prised out by means of the
cut-outs provided in the cam follower rim
(photo).
3Once the shim is extracted, establish its
thickness and change it for a thicker or
thinner one to bring the previously recorded
clearance within specification. For example,
if the measured valve clearance was 1.27
mm (0.05 in) too great, a shim thicker by this
amount will be required. Conversely, if the
clearance was 1.27 mm (0.05 in) too small, a
shim thinner by this amount will be required.
4Shims have their thickness (mm) engraved
on them; although the engraved side should
be fitted so as not to be visible, wear still
occurs and often obliterates the number. In
this case, measuring their thickness with a
metric micrometer is the only method to
establish their thickness (photo).

5In practice, if several shims have to be
changed, they can often be interchanged, so
avoiding the necessity of having to buy more
new shims than is necessary.
6If more than two or three valve clearances
are found to be incorrect, it will be more
convenient to remove the camshaft carrier for
easier removal of the shims.
7Where no clearance can be measured, even
with the thinnest available shim in position,
the valve will have to be removed and the end
of its stem ground off squarely. This will
reduce its overall length by the minimum
amount to provide a clearance. This job
should be entrusted to your dealer as it is
important to keep the end of the valve stem
square.
8On completion, refit the camshaft cover and
gasket.
27 Camshaft and camshaft
carrier- removal and refitting
3
1Disconnect the battery.
2Remove the air cleaner (see Chapter 3).
3Disconnect the fuel filter hose from the fuel
pump and tie it back, out of the way.
4Identify and then disconnect any electrical
leads which must be moved away to enable
the camshaft cover to be withdrawn.
5Identify and disconnect any vacuum gases
which must be moved away to enable the
camshaft cover to be withdrawn.
6Unscrew the securing nuts and remove the
camshaft cover.
7Turn the crankshaft pulley nut until No. 4
piston is at TDC. This can be established as
described in Section 28.
8Unbolt and remove the timing belt cover.
9Check that the timing mark on the camshaft
sprocket is aligned with, and adjacent to the
pointer on the timing belt cover backplate.
10Restrain the timing belt with the hand and
release but do not remove the camshaft
sprocket bolt. Release the belt tensioner
pulley by slackening the pulley centre nut.
Push the timing belt evenly from the
sprockets, noting which way round the belt isfitted if it is to be completely removed. The
lettering on the belt is normally legible from
the crankshaft pulley end of the engine when
the belt is as originally fitted.
11Unbolt the camshaft carrier and lift it
sufficiently from the cylinder head to break the
seal of the mating faces. Note: It is important
not to allow the cam followers to pull out; they
must be retained in their original locations.
This can be done if the carrier is raised very
slowly, until the fingers can be inserted to
prise the cam followers onto their respective
valve spring retainers. It is unlikely that the
valve clearance adjusting shims will be
displaced from their recesses in the cam
followers because of the suction of the
lubricating oil, but watch that this does not
happen; the shims must also be retained in
their originally fitted sequence.
12Remove the previously loosened
camshaft sprocket bolt and take the sprocket
from the camshaft.
13Unbolt and remove the camshaft end
cover with its gasket. Withdraw the camshaft
(photos).
14Refitting is a reversal of the removal
process, but observe the following points.
15Use new gaskets.
16Retain the cam followers and shims in
their bores in the camshaft carrier with thick
grease; they must not be allowed to drop out
when the carrier is lowered onto the cylinder
head.
17If the crankshaft or camshaft have been
moved from their set positions, re-align the
sprocket timing mark with the pointer on the
belt cover and the crankshaft pulley or
flywheel with the TDC mark. This must be
observed otherwise the valves may impinge
upon the piston crowns when the camshaft
lobes compress any of the valve springs
during bolting down of the carrier.
18Screw in the carrier bolts and tighten
them to the specified torque (photo).
19Refit and tension the timing belt as
described in Section 28.
20Refit the camshaft cover and gasket.
21Refit the hose and air cleaner.
22Reconnect the battery.
28 Timing belt- renewal
3
1Set No. 4 piston at TDC. Do this by turning
the crankshaft pulley nut or by jacking up a
front roadwheel, engaging a gear and turning
the wheel until the mark on the flywheel is
opposite to the TDC mark on the flywheel
bellhousing aperture. Remove No. 4 spark
plug, place a finger over the plug hole and feel
the compression being generated as the
crankshaft is rotated and the piston rises up
the cylinder bore.
2On some models the TDC marks on the
crankshaft pulley and belt cover may be
visible and can be used instead.
3Remove the alternator drivebelt (Chapter 2,
Section 8). Unbolt and remove the timing belt
cover.
4Check that the timing mark on the camshaft
sprocket is aligned with the pointer on the belt
cover backing plate (photo).
5Slacken the nut in the centre of the
tensioner pulley and push in on the support to
release the tension on the belt, then retighten
the nut. Slide the drivebelt off the pulleys.
6Check that the crankshaft and camshaft
pulleys have not been moved from their
previously aligned positions.
7To check that the auxiliary shaft sprocket
has not moved, take off the distributor cap
and check that the contact end of the rotor
arm is aligned with No. 4 HT lead contact in
the cap.
1•24 1116 cc and 1301 cc engine
28.4 Camshaft sprocket alignment marks
27.18 Tightening a camshaft carrier bolt27.13B Withdrawing camshaft from carrier27.13A Removing camshaft end cover

8Fit the new belt. Start at the crankshaft
drive pulley and, taking care not to kink or
strain the belt, slip it over the camshaft pulley.
The camshaft may have to be turned slightly
to mesh the pulley with the teeth on the belt.
Fit the belt on the tensioner pulley last; if this
is difficult, do not lever or force the belt on,
recheck the belt (photo).
9Release the tensioner nut and rotate the
crankshaft through two complete revolutions.
Retighten the nut. The belt tension may be
checked by twisting it through 90º with the
finger and thumb. It should just turn through
this angle without undue force. Note: The
above procedure serves only as a rough guide
to setting the belt tension - having it checked
by a FIAT dealer at the earliest opportunity is
recommended.
10Refit the timing belt cover (photo). Fit and
tension the alternator drivebelt (Chapter 2,
Section 8).
29 Cylinder head-
removal and refitting
3
1Drain the cooling system (see Chapter 2).
2Disconnect the battery.
3Disconnect and plug the carburettor fuel
hoses.
4Disconnect the throttle and choke linkage
from the carburettor. 5Disconnect the HT leads from the spark
plugs.
6Disconnect the brake servo vacuum hose
from the intake manifold.
7Disconnect the coolant hoses from the
thermostat housing.
8Disconnect the crankcase ventilation
system hoses from the rocker cover and
carburettor.
9Unbolt and remove the timing belt cover.
10Release the timing belt tensioner pulley
bolt, then lever the pulley against the spring
plunger and retighten the bolt to retain the
tensioner pulley in the non-tensioned position.
Slip the belt from the camshaft sprocket.
11Disconnect the coolant hoses from the
carburettor and intake manifold.
12Disconnect the exhaust downpipes from
the manifold.
13If a crowfoot type wrench is available, the
cylinder head nuts and bolts can be removed
and the complete cylinder head camshaft
carrier assembly withdrawn (photo).
14If this type of wrench is not available
however, remove the carrier first as described
in Section 27.
15If a crowfoot is available, unscrew the
cylinder head nuts and bolts evenly and
progressively starting with the centre ones
and working towards both ends.
16Rock the cylinder head by gripping the
manifolds. Note: Do not insert a lever in
the gasket joint to prise the head from the
block.17Pull the head off the studs and remove it
to the bench. Remove and discard the old
cylinder head gasket.
18Unbolt and remove the hot air collecting
shield for the air cleaner from the exhaust
manifold. The exhaust and inlet manifolds can
now be unbolted. The carburettor may remain
on the inlet manifold.
19Overhaul and decarbonising of the
cylinder head is described in Section 39.
20Refitting is a reversal of the removal
process, but make sure the crankshaft and
camshaft timing marks are set as described in
Section 28 to avoid the valve heads digging
into the piston crowns when the head is
refitted.
21Always use new gaskets. The cylinder
1116 cc and 1301 cc engine 1•25
Fig. 1.29 Timing belt arrangement (Sec 28)
1 Camshaft sprocket
2 Tensioner pulley locknut
3 Timing mark on crankshaft front oil seal
retainer
4 Crankshaft sprocket
5 Crankshaft sprocket timing mark
6 Auxiliary shaft sprocket
7 Tensioner bracket bolt
8 Tensioner pulley
9 Timing belt
10 Tensioner bracket
11 Tensioner spring
28.8 Slipping timing belt onto tensioner
pulleyFig. 1.28 TDC marks (1) at front of engine
(Sec 28)
Fig. 1.30 Cylinder head bolt tightening
sequence (Sec 29)28.10 Tightening timing belt cover nut29.13 Using a crowfoot type wrench on a
cylinder head bolt
1

plate to the crankcase, using a new gasket
(photos).
11Fit the belt sprocket and partially tighten
its bolt. Then, using an oil filter strap wrench
or similar device to hold the sprocket against
rotation, tighten the bolt to the specified
torque. Take care not to damage the teeth of
the sprocket, which is of fibre construction
(photo).
Oil sump, sump pan and
breather
12Fit the oil drain pipe by tapping it into
place, squarely in its hole in the crankcase.
Tighten its retaining bolt (photo).
13Bolt up the oil pump, using a new gasket
at its mounting flange (photo).14Fit the sump (using a new gasket) and
tighten the securing screws to the specified
torque. Note the reinforcement washers
(photo).
15Insert the oil pump/driveshaft into the
distributor hole. This does not have to be
specially positioned as the distributor is
splined to the shaft and can be set by moving
its location in the splines (refer to Chapter 4)
(photo).
16Push the breather into its crankcase
recess and tighten its securing bolt (photos).Flywheel, crankshaft sprocket
and pulley
17Make sure that the flywheel-to-crankshaft
mounting flange surfaces are clean. Althoughthe bolt holes have unequal distances
between them, it is possible to fit the flywheel
in one of two alternative positions at 180º
difference. Therefore if the original flywheel is
being refitted, align the marks made before
removal.
18If a new flywheel is being fitted, or if
alignment marks were not made before
dismantling, set No. 1 position at TDC
(crankshaft front Woodruff key pointing
vertically). Fit the flywheel to its mounting
flange so that its timing dimple is uppermost
and in alignment with the relative position of
the TDC mark on the flywheel housing
inspection window.
19Insert the bolts and tighten them to the
specified torque, jamming the ring gear to
1116 cc and 1301 cc engine 1•31
42.11 Tightening camshaft sprocket bolt.
Note sprocket locking device42.10B Tightening auxiliary shaft end plate
bolt42.10A Auxiliary shaft end plate and
gasket
42.16B Crankcase breather and retaining
bolt42.16A Crankcase breather seal42.15 Fitting oil pump driveshaft
42.14 Tightening sump pan bolt42.13 Locating oil pump and gasket42.12 Tightening oil drain pipe bolt
1

prevent the flywheel turning. Fit the engine
endplate (photo).
20Fit the timing belt sprocket to the front
end of the crankshaft (photo).
21Fit the crankshaft pulley and the nut;
tighten it to the specified torque, again
jamming the starter ring gear to prevent the
crankshaft from rotating (photo).
Cylinder head
22Refitting is described in Section 29.
Camshaft carrier and camshaft
23Refitting is described in Section 27.
Timing belt and tensioner
24Refitting is described in Section 28, but
make sure that the belt cover rear plate is
bolted into position. If the engine mounting
bracket was removed, bolt it into positioncomplete with the tensioner plunger to
provide spring pressure to the belt pulley
(photos).
Valve clearances
25Check the valve clearances as described
in Section 26.
26Using new gaskets, bolt on the camshaft
carrier cover plate and the inlet and exhaust
manifolds using new gaskets. Fit the exhaust
manifold hot air collector plate (photo).
27Locate the engine rear plate on its dowels
by sliding it behind the flywheel (photo).
43 Engine ancillaries- refitting
1Bolt on the carburettor (Chapter 3). 2Fit the coolant pump and thermostat
housing (Chapter 2).
3Fit the alternator and tension the drivebelt
(Chapters 9 and 2).
4Fit the distributor (Chapter 4).
5Fit the fuel pump (Chapter 3).
6Fit the clutch (Chapter 5).
7Fit a new oil filter cartridge (Section 2 of this
Chapter).
44 Engine/transmission-
reconnection and refitting
3
1Offer the transmission to the engine making
sure that the clutch has been centralised as
described in Chapter 5 (photo).
1•32 1116 cc and 1301 cc engine
44.1 Offering transmission to engine42.27 Engine rear plate42.26 Tightening a camshaft carrier cover
nut
42.24C Engine mounting bracket with belt
tensioner plunger (arrowed)
42.24B Belt cover mounting stud42.24A Belt cover rear plate
42.21 Crankshaft pulley and nut42.20 Fitting crankshaft timing belt
sprocket42.19 Tightening flywheel bolts

to the engine. Also reconnect the brake servo
hose to the intake manifold (photos).
22Reconnect the leads to the reversing lamp
switch. Reconnect the transmission earth lead
(photos).
23Reconnect the clutch cable and adjust as
described in Chapter 5.
24Reconnect the speedometer drive cable
to the transmission and tighten the knurled
retaining ring.
25Reconnect the low tension lead to the
distributor and the high tension lead to the
ignition coil.
26Reconnnect the electrical leads to thestarter motor, the oil pressure and
temperature switches and the coolant
temperature switch.
27Connect the leads to the alternator.
28Refit the air cleaner.
29Refill the cooling system. Refill the engine
with oil.
30Reconnect the battery.
31Refit the bonnet and connect the
windscreen washer tube.
32Fit the inner wing protective shields
(photo).
45 Engine- initial start-up after
major overhaul
4
1If new bearings and rings have been fitted,
it is likely that the engine will be stiff to turn so
make sure the battery is well charged.
2Switch on the ignition and check that
appropriate warning lights come on.
3Start up the engine. If it refuses to start,
refer to the “Fault Finding” Section in the
Reference section of this Manual.
4Watch the oil pressure warning light and
alternator charging indicator light. If there is
no charge or if the oil pressure warning light
does not go out after a second or two, havinghad time to fill the new oil filter, switch off and
recheck.
5If the warning lights go out, set the engine
to run on fast idle and check the engine for
leaks.
6Check the coolant level; it will probably go
down as air locks are filled.
7Keep the engine running at a fast idle and
bring it up to normal working temperature. As
the engine warms up, there will be some odd
smells and smoke from parts getting hot and
burning off oil deposits.
8When the engine running temperature has
been reached, adjust the idling speed, as
described in Chapter 3. Check and, if
necessary, adjust the ignition timing using a
stroboscope (see Chapter 4).
9Stop the engine and wait a few minutes;
check to see if there are any coolant or oil
leaks.
10Road test the car to check that the engine
is running with the correct smoothness and
power. If it does not, refer to “Fault finding” in
the Reference section of this Manual. Do not
race the engine. If new bearings and/or
pistons and rings have been fitted, it should
be treated as a new engine and run it at
reduced speed for at east 800 km (500 miles).
11After 800 km (500 miles) change the
engine oil and filter.
1•34 1116 cc and 1301 cc engine
44.32 Inner wing protective shield44.26B Coolant temperature switch44.26A Oil pressure warning switch
44.22B Transmission earth lead
44.22A Reversing lamp switch on
transmission44.21B Brake servo hose at manifold44.21A Heater hose at manifold

Fault finding - all engines
Note: When investigating starting and uneven running faults, do not be tempted into snap diagnosis. Start from the beginning of the check
procedure and follow it through. It will take less time in the long run. Poor performance from an engine in terms of power and economy is not
normally diagnosed quickly. In any event, the ignition and fuel systems must be checked first before assuming any further investigation needs to
be made.
All engines 1•35
1
Engine fails to turn when starter operated
m mBattery discharged
m mBattery terminals loose or corroded
m mBattery earth to body defective
m mEngine/transmission earth strap broken or loose
m mDisconnected or broken wire in starter circuit
m mIgnition/starter switch defective
m mStarter motor or solenoid defective (see Chapter 9)
m mMajor mechanical failure (seizure) or long disuse (piston rings rusted
to bores)
Engine turns and fails to start
m mBattery discharged
m mBattery terminals loose or corroded
m mBattery or engine earth strap loose
m mStarter motor connections loose
m mOil in engine/transmission too thick
m mStarter motor defective
m mVapour lock in fuel line (in hot conditions or at high altitude)
m mBlocked float chamber needle valve
m mFuel pump filter blocked
m mChoked or blocked carburettor jets
m mFaulty fuel pump
m mFuel tank empty
m mOther fuel system fault (see Chapter 3)
m mShorted or disconnected low tension leads
m mDirty, incorrectly set, or pitted contact breaker points
m mContact breaker point spring earthed or broken
m mFaulty condenser
m mDefective ignition switch
m mFaulty coil
m mDamp or dirty HT leads, distributor cap or plug bodies
m mBroken, loose or disconnected LT leads
m mIgnition leads connected wrong way round
m mOther ignition fault (see Chapter 4)
m mValve timing incorrect (after rebuild)
Engine fires but will not run
m
mInsufficient choke (cold engine)
m mFuel starvation or tank empty
m mIgnition fault (see Chapter 4)
m mOther fuel system fault (see Chapter 3)
Engine stalls and will not restart
m
mToo much choke allowing too rich a mixture to wet plugs
m mFloat damaged or leaking or needle not seating
m mFloat lever incorrectly adjusted
m mIgnition failure - sudden
m mIgnition failure - misfiring precedes total stoppage
m mIgnition failure - in severe rain or after traversing water splash
m mNo petrol in petrol tank
m mPetrol tank breather choked
m mSudden obstruction in carburettor
m mWater in fuel system
Engine slow to warm up
m
mChoke linkage maladjusted
m mAir cleaner temperature control unit defective
m mThermostat stuck open (see Chapter 2)
m mOther fuel system fault (see Chapter 3)
Difficult starting when cold
m
mInsufficient choke
m mFouled or incorrectly gapped spark plugs
m mDamp or dirty HT leads, distributor cap or spark plug bodies
m mDirty or maladjusted contact breaker points
m mOther ignition fault or timing maladjustment (see Chapter 4)
m mFuel system or emission control fault (see Chapter 3)
m mPoor compression (may be due to incorrect valve clearances, burnt
or sticking valves, blown head gasket, worn or damaged pistons,
rings or bores)
m mIncorrect valve timing (after rebuild)
Difficult starting when hot
m
mIncorrect use of manual choke
m mFuel line vapour lock (especially in hot weather or at high altitudes)
m mIncorrect ignition timing
m mOther fuel system or emission control fault (see Chapter 3)
m mPoor compression (see above)
Engine lacks power
m
mIgnition timing incorrect
m mContact breaker points incorrectly gapped
m mIncorrectly set spark plugs
m mDirty contact breaker points
m mDistributor automatic advance and retard mechanisms not
functioning correctly
m mOther ignition system fault (see Chapter 4)
m mAir cleaner choked
m mCarburation too rich or too weak
m mFuel filter blocked
m mAir filter blocked
m mFaulty fuel pump giving top and fuel starvation
m mOther fuel system fault (see Chapter 3)
m mPoor compression
m mValve clearances incorrect
m mCarbon build-up in cylinder head
m mSticking or leaking valves
m mWeak or broken valve springs
m mWorn valve guides or stems
m mWorn pistons and piston rings
m mBurnt out valves
m mBlown cylinder head gasket (accompanied by increase in noise)
m mWorn pistons and piston rings
m mWorn or scored cylinder bore
m mBrakes binding
Engine misfires throughout speed range
m
mDefective or fouled spark plug
m mLoose, cracked or defective HT lead
m mMaladjusted, sticking or burnt valves
m mIgnition timing incorrect
m mBlown head gasket
m mFuel contaminated
m mOther ignition fault (see Chapter 4)
m mOther fuel system fault (see Chapter 3)
Poor engine braking
m
mHigh idle speed
m mOther fuel system fault (see Chapter 3)
m mLow compression