Testing Vacuum Advance; Checking Distributor Cam Wear - CEN-TECH 40963 Set Up And Operating Instructions Manual

Testing Vacuum advance

1. Speed the engine up slowly to the
manufacturer's specified speed for
this test (often 2000 RPM) and leave
the vacuum line detached from the
distributor.
2. Aim the Timing Light at the timing
marks and turn the timing advance
knob on the back of the timing light
up slowly until the timing mark moves
to Tdc or 0.
3. Connect the vacuum line to the
distributor.
4. If the timing mark stays still, the
trouble could be a plugged line,
a leaky diaphragm, or a frozen
distributor plate. See a certified
mechanic if the mark doesn't move.
5. Read the amount of vacuum advance
from the timing marks on the engine.
Compare with vehicle service
manual.
reV 07h, 09g
SKU 40963 For technical questions, please call 1-800-444-3353.

checking distributor cam Wear

1. This test is done after the timing has
been set and the timing light lines up
with the reference pointer for cylinder
number 1.
#1 cylinder
6 cylinder
Opposite
2
cylinder
6
3
Opposite
cylinder
note: The opposite cylinder is opposite
the #1 Cylinder on Distributor Cap.
Figure 3
2. Connect the Timing Light to the
spark plug wire directly opposite (180
degrees) from the number 1 cylinder
on the distributor cap.
(See Figure 3)
3. Start the engine and aim the Timing
Light towards the timing mark. The
reading should be the same as when
the Timing Light was connected to
the number 1 cylinder wire. If not,
the probable cause is a worn out
distributor cam, bushing, or bearing,
or bent distributor shaft. Contact
a qualified service technician for
repairs.
4 cylinder
3
4
Opposite
cylinder
1
2
#1 cylinder
4
1
5
8 cylinder
5 7
6 2
3 1
4 8
#1 cylinder
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