Values Which Can Be Measured - tecnotest 138-E Manuel D'utilisation

__________________________________________________________________________ TIMING LIGHT
1.3 -

Values which can be measured

The timing light is equipped with a microprocessor allowing to measure the
engine revolutions and the advance degrees of the gasoline engines. It also allows
the measurement of the VOLT, of the PEAK VOLT (ex. for magnetic boosters) and of
the DWELL value (points dwell) expressed in degrees.
The engine revolutions number is measured by means of an induction clamp connected
to the plug wire of 1st cylinder (regardless of the engine cylinder number) through
which the instrument receives the electrical signal the coil sends to the plug.
In case of engines with D.I.S or static ignition it is necessary to use the special
RPM Adaptor which is not on issue with the instrument.
The points DWELL indicates the value of rotation degrees the distributor has to perform
between the ignition of two subsequent sparks to have the points open.
This value is measured thanks to the work of the induction clamp and of the yellow
clamp to be connected to the coil negative pole.
The yellow clamp measures only the pulses that the coil sends to the various plugs
while the induction clamp supplies the cylinder in the ignition phase according to the
plug wire it is connected to.
For instance, in case you would like to know the DWELL of 2° cylinder of the scheme b
follow the instructions below:
•
Connect the yellow clamp to the coil negative pole.
•
Connect the induction clamp to the plug wire of 4° cylinder (previous cylinder
following the ignition sequence).
•
The microprocessor ignores the ignition signals from the yellow clamp until the
induction clamp warns the microprocessor that the last measured signal comes
from the 4° cylinder wire.
•
Now the microprocessor starts counting the degrees until it measures a new signal
(which obviously will come from the 2° cylinder plug).
•
The instrument displays the obtained angle.
The ignition advance control is performed by enabling the flash of the timing light.
Act on the special DEVIATOR to make the TDC fixed and movable references
correspond. When the two references correspond read on the display the advance
value.
In case it does not correspond to the manufacturer's values it is necessary to operate
on the engine.
OPERATING INSTRUCTIONS
ENGINE REVOLUTIONS
CONTACT POINTS DWELL (DWELL)
ADVANCE
31