3116 and 3126 Truck Engines Finding Top Center Position For No. 1 Piston

Top Center (TC) Bolt Location (Typical Example)
(1) Top center (TC) bolt. (2) Timing hole. (3) Flywheel housing.

NOTE: Depending on engine application, the timing hole (2) is located at either the left front face or right front face of the flywheel housing.

1. Remove plug from timing hole (2) on front of flywheel housing.

NOTE: Turn the engine with the four large bolts on the front of the crankshaft. Do not use the eight small bolts on the front of the crankshaft pulley.

2. Put 8T0292 top center (TC) bolt (1) in hole. Now turn the engine flywheel counterclockwise until the top center (TC) bolt engages with the threaded hole in the flywheel.

NOTE: If the flywheel is turned beyond the point that the top center (TC) bolt engages in the threaded hole, the flywheel must be turned clockwise approximately 30 degrees. Then turn the flywheel counterclockwise until the to center (TC) bolt engages with the threaded hole. The reason for this procedure is to make sure the backlash is removed from the gears when the No. 1 piston is put on top center.

3. Remove the valve cover.

4. The intake and exhaust valves for the No. 1 cylinder are fully closed if No. 1 piston is on the compression stroke and the rocker arms can be moved by hand. If the rocker arms cannot be moved and the valves are slightly open, the No. 1 piston is on the exhaust stroke. Make reference to charts for CRANKSHAFT POSITIONS FOR VALVE LASH SETTING to find the correct cylinder(s) to be checked/adjusted for the stroke position of the crankshaft when the top center (TC) bolt has been installed in the flywheel.

NOTE: When the actual stroke position is identified, and the other stroke position is needed, it is necessary to remove the top center (TC) bolt from the flywheel, turn the flywheel counterclockwise 360 degrees, and reinstall the top center (TC) bolt.

NOTE: The timing hole is only used for valve lash setting and to time the engine electronically with the 7X1200 timing adapter group.

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