TIMING
PSU OR
MODEL
50
INJECTION
PUMPS
One
of
two
methods can be used to determine the
proper timing button to time the fuel injection pump
correctly to the engine.
Method
1-Timing
by
Calculation
This procedure is used, when all dimensions are
available for replacing an old pump, before the pump
is installed. Timing by calculation requires the port
closing dimension and button thickness from the
pump being replaced.
It
also requires the port closing
dimension of the new pump. Put the dimensions in
the PORT CLOSING FORMULA and calculate the
new button thickness. After determining the timing
button thickness find the button code
in
Table
8.
If
injection pump is removed from the engine, make
sure the steel shims between pump and cylinder
block mounting remain the same. These shims main-
tain proper gear backlash.
Do
not change the pump mounting
Ez2
shim’s total thickness or the proper
pump gear to camshaft
gear
mesh will
be
affected.
The shim thickness is establishedat the factory dur-
ing engine assembly and does not change unless a
new cylinder block is installed.
Port
Closing Formula:
The procedure for determin-
ing the proper port closing (PC) timing button for a
new or replacement pump is as follows:
1.
Remove old pump.
2.
Determine port closing dimensions and original
button thickness from old pump.
A.
Write down port closing dimension given on
old
pump flange and port closing dimension
given on new pump flange. See example.
B.
Use a pair of channel lock pliers
or
screw-
driver to remove tappet, retaining ring, and
timing button from old injection pump (Figure
48).
Use nurnberor letter code on timing but-
ton to obtain dimension of old timing button
fromTable8.Thiscodeshould
bethesameas
the code number stamped on injection pump
(Figure
48).
OnallPSUpumpsbesureto
E3
hold the pump drive gear
securely against the pump body when remov-
ing the tappet. If not, the pump will come
apart and be difficult
to
assemble. The meter-
ing sleeve wlll drop off the plunger if the gear
and plunger are removed.
If
fhe plunger port
is
not closed by the sleeve, there wlll be no
fuel delivery and the pump wiil not operate.
3.
Add dimension on
old
pump flange
to
timing but-
ton dimension. See example.
Example:
Inches
(mm)
Port
closing dimension
of
old pump
1.109 (28.169)
Button thickness
of
old pump
+
.107 (2.719)’
Total
1.216 (30.887)
Port
closing dimension
of
new pump
-1.094 (27.788)
Required button thickness
of
new
pump
.122 (3.099)
4.
Subtract port closing dimension given on new
pump flange from total dimension for old pump.
5.
Use dimension calculated to select new timing
button that is nearest the calculated dimension.
Install new timing button
m
pump and install
tappet on pump.
6.
Install injection pump. Referto lNJECT/ON
PUMP
INSTAL LA TI0 N.
MAXIMUM
THROTTLE
STOP
SCREW
D
O-RING
KEEPS TA
IN
DURING
HAND
GROOVE
/
TAPPET
FIGURE
48.
TAPPET
REMOVAL
Method
2-Flow
Timing Injection Pump
This procedure is used when dimensionsfrom the old
pump are lost or when a new cylinder block is
installed. Clean diesel fuel is used, when
flow
timing,
to determine if the proper timing button has been
installed.
If the pump is removed from the engine, be sure the
steel shims between the pump and the cylinder block
mounting are the same. These shims maintain proper
gear backlash. The number stamped on the cylinder
block injection pump mounting pad indicates the
proper shim thickness. This thickness does not
change when anew pump is installed.
It
changes
only
when a new cylinder block is installed.
47
Redistribution or publication of this document,
by any means, is strictly prohibited.
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