Usage:
3500 Family Of Engines
Reference: Service Magazine; April 20, 1987; Page 9; "Fuel Injection Timing Adjustment". Service Magazine; November 19, 1984; Page 12; "Additional Information For Correct Fuel Injector Timing".
Reference: Tool Announcement, NEHG3304, "1U8869 Digital Dial Indicator".
Fuel injection timing is a critical engine adjustment. If done incorrectly, low engine power, high exhaust temperature, increased exhaust smoke, piston failures, etc. can result. All these problems have been caused by incorrect timing adjustment on the 3500 Family of Engines. Confusion about the adjustment procedure is believed to be the cause of the majority of the incorrect timing adjustment problems.
A new 1U8869 Digital Dial Indicator is available primarily for engine fuel systems. Using this digital dial indicator will simplify the fuel timing procedure, and therefore reduce confusion. Caterpillar recommends that the 1U8869 Indicator be added to your 6V7880 Timing and Fuel Setting Group.
New digital dial indicator.
NOTE: At this time, it is necessary to continue using the 6V3075 Dial Indicator to measure fuel setting. The distance between the end of the indicator plunger stem and the body of the indicator is shorter for the 1U8869 Indicator than for the 6V3075 Indicator, and a correct length contact point is not available. Also, the 1U8869 Indicator Plunger has only 12.7 mm (.50") travel.
The main improvement in the new indicator is that it can be programmed to read any desired number at a particular plunger position. The former sweep arm dial indicator, when used to measure unit injector fuel timing, measured the difference between the height of the gauge block and the height of the injector follower. However, the same dial indicator is used also for fuel setting, and the positive direction for plunger movement of this dial indicator is in the opposite direction for timing as it is for fuel setting. The result is that the sweep arm of the dial indicator moves in the normally negative direction to indicate positive movement for timing. This can cause confusion, especially for servicemen who only occasionally do this work.
The new indicator can be programmed so the actual timing is displayed. For example, if the timing dimension is 87.30 mm, the indicator can be programmed to show 87.30 mm when that dimension is obtained. This should eliminate any possible confusion on the timing adjustment.
Programming the new indicator is similar to programming a digital watch. See the following procedure.
Programming The Indicator And Its Installation
1. First, program the indicator to read the actual timing dimension. Since the gauge block in the timing and fuel setting tool group is 87.00 mm, the dial indicator is to be programmed for 87.00 mm.
a. Turn the indicator ON by pushing the "on/off" button.
b. Push the "in/mm" button so the display shows mm.
c. A negative sign (-) should be in the display window under REV. If that space is blank, push the ± so the display shows (-). When this is done, plunger movement into the indicator will show on the display as negative movement, and plunger movement out of the indicator as positive movement.
d. Push and hold the preset button down until there is a flashing (P) in the upper right corner of the display, and then release the button.
e. Push and hold the preset button down until the flashing (P) disappears, and a flashing indicator bar is seen in the lower left corner of the display, and then release. Momentarily pushing the preset button will cause a minus sign to appear or disappear above the flashing indicator. Use the preset button to make this position blank.
f. Push and hold the preset button down until flashing indicator begins to flash under the first number position (fourth position to the left of the decimal), then release. Momentarily pushing the preset will cause the display number in that position to change. Use the preset until this position reads zero (0).
g. Use the preset button to move the flashing indicator and change the display numbers until the display shows 0087.00 mm. Push and hold the preset button until the flashing (P) is shown in the upper right corner of the display, and then release. Momentarily push the preset button so the flashing (P) and the zeros to the left of 87.00 mm disappear.
h. The indicator can now be turned off if desired. The indicator will retain the preset number in memory (only one preset number is retained). To recall the preset number, repeat Steps 1a through 1d.
2. Install a 5P4160 Contact Point [19 mm (.75")] in the indicator stem.
3. Install the indicator in the timing bracket. Leave the collet loose.
4. Place the bracket and indicator on the 6V3117 Gauge Block with the extension rod of the bracket on the step of the gauge block. Position the indicator in the bracket so the indicator plunger has adequate travel and tighten the collet.
5. Repeat Steps 1a through 1d.
6. Momentarily push the "preset" button. The display should show 87.00 mm. Place the bracket and dial indicator on the injector. See the Service Manual for correct procedure. The dial indicator display will show the timing dimension directly, for example, 87.70 mm will appear as 87.70 mm and 86.50 mm will appear as 86.50 mm.