TM 5-4310-452-14
5-4. TOP DEAD CENTER (TDC) SETTING.
This Task Covers: Top Dead Center (TDC) Setting
Initial Setup:
Equipment Conditions:
Tools/Test Equipment:
• Engine off.
• General mechanic's tool kit
• Left and right door assemblies open,
• Degree indicator (003-0498)
• Front baffle assembly removed (see paragraph
• Dial indicator (003-0543)
5-27) .
• TDC fixture (003-0498)
• TDC pointer (003-0678)
TOP DEAD CENTER (TDC) SETTING
NOTE
Use this procedure when either the flywheel or crankshaft pulley have been replaced, or the
timing marks cannot be seen.
1.
Remove No. 1 valve cover (see paragraph 4-12).
2.
Set No. 1 cylinder valves in overlap position (see paragraph 4-13).
3.
Using 36 mm socket and breaker bar, turn crankshaft (8) clockwise one full revolution, then turn 1/4-turn more.
4.
Install TDC fixture (5) in place on No. 1 cylinder head (7).
5.
Turn T-handle (1) and depress rocker arm (6) 0.197-0.236 in, (5-6 mm).
6.
Install dial indicator (3) in TDC fixture (5). Preset dial indicator load at 7 mm, and tighten locknut (2).
7.
Install degree indicator (10) on crankshaft pulley (11). Install TDC pointer (12) behind engine front cover bolt (9).
8.
Turn crankshaft (8) clockwise until rocker arm (6) moves dial indicator pointer (4). Continue to turn crankshaft slowly
until dial indicator pointer reverses direction, then stop.
9.
Set dial indicator pointer (4) at zero.
10. Position degree indicator (10) on crankshaft pulley (11) with TDC pointer (12) set at zero.
11. Turn crankshaft (8) counterclockwise until dial indicator pointer (4) completes one full revolution, and is pointing
exactly 0.1 mm (10 graduations) past zero on dial indicator (3).
12. Record the position indicated by the TDC pointer (12) on the dial indicator (3).
13. Turn crankshaft clockwise until dial indicator pointer completes one full revolution and is pointing exactly 0.1 mm (10
graduations) past zero on the dial indicator (3).
14. Record the position indicated by the TDC pointer (12) on the degree indicator (10).
NOTE
Top dead center (TDC) is the middle of the two positions recorded in steps 12 and 14.
15. Find the average of the two positions recorded in steps 12 and 14.
5-6
