Facom X.730B Instruction Manual Download

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No variations or wrong variations could

be caused by: diaphragm of the vacuum

advance variator cracked.

Note : In breaker points systems, an

excessive wear of the distributor’s parts
causes abnormal advance variations and
a decreased engine performance. A too
low Dwell angle causes an insuffi cient
ignition; a too high Dwell angle causes a
premature burning of contacts. Remember
to check the advance after repair.

6. CHECKING THE RPM NUMBER

• Reading up to 19 990 RPM can be made

through the inductive clamp.

Direct measurements up to 6000 RPM are

possible with the stroboscope. In this case

refer to page 7.

• In carburettor systems and in some early

electronic injection systems, adjust the ad-

vance through the special screw for a correct

air/petrol mixture until obtaining a regular

engine rotation.

Note : A perfect idle adjustment limits

fuel consumption, emission of harmful

exhaust gases and avoids engine stops.

7. CHECKING BREATHER PIPES

• The check is made by disconnecting the

tubes that go from the crankcase to the

engine head or to the carburettor. By closing

the top of the tube with a fi nger, a drop of

50 or more RPM should occur. If not, check

that there are no fi lter occlusions or possible

damages of the pipe’s valves.

8. CHECKING THE MECHANICAL
POSITION OF TIMING MARKS

• To check only the timing marks’ position,

bring the display to 00,1 through the C– key.

• Bring the engine to idle and disconnect the

vacuum tube or observe the instructions of

the manufacturer.

By pressing the D key, the timing light

should fl ash.

If the timing mark is too far from the correct

position, rotate the distributor or check

that the distribution belt has not jumped a

cog. The same procedure may be used for

checking the marks of centrifugal advance.

In systems with ECU, check the engine

temperature sensor.

9. ADVANCE MEASUREMENT

• Check that the RPM number is the same

shown in the manufacturer’s data.

• Press the C± key until the display shows

the number of degrees indicated in the

manufacturer’s data.

Lighten the TDC marks on the pulley and

crankcase taking care not to confuse them

with the other ones.

Check that the error in the alignment of

TDC marks is within the tolerances foreseen

by the manufacturer, otherwise turn the

distributor. In ECU systems, check that the

timing belt has not jumped a cog or that

the engine temperature sensor is not faulty.

• If the TDC mark swings too much check

the distribution belt and the distributor

mechanisms in point systems.

Note : In some vehicles, reference marks

can be better lightened by keeping the
timing light in an uncomfortable position
for the reading. In this case store the
reading when the marks are aligned by
releasing the key D, then read the value
within 6 seconds.

1 0 . C E N T RI F U G A L A D VA N C E
MEASUREMENT

• Run the engine to the speed indicated in

the data manual.

• Press the C± key until the display shows

the number of degrees indicated in the

data manual or in manufacturer’s data;

TDC marks on the crankcase and on the

crankshaft pulley should be in line.

If the error is excessive, check the engine

temperature sensor in ECU systems; if the

mark swings too much, or moves irregularly

during accelerations, check that the timing

belt is not loose.

In points systems check the contact spring;

the centrifugal mechanism could otherwise

be worn as well as the pivots or the distri-
butor shaft.
Note : A faulty centrifugal timing can result

in lack of pick-up and fl at points in engine
power at certain engine speeds.

11. CHECKING THE VACUUM
ADVANCE

• By connecting the vacuum tube, advance

should increase. It can be measured by

bringing TDC marks in line.

In points systems: if there is no variation or

if the advance is too much out of tolerances,

the diaphragm and the baseplate should be

checked.

Note : In ECU controlled ignition/injection

systems, if the advance caused by the
vacuum device does not correspond
to the manufacturer’s specifi cations, it
can be due to a wrong operation of the
vacuum sensor.

12. CHECKING THE ACCELERATION
RETARD

This check can be made in engines provided

with this device.

• Press the C± key to bring the display to

00,1. By connecting the vacuum retard tube

during sudden accelerations, the advance

should momentarily decrease.

In case of anomalous variations, check the

diaphragm or other mechanical parts.

13. VOLTAGE MEASUREMENTS

Measurements of direct battery voltage at

cranking, alternator’s charge, voltage varia-