CYLINDER GP-AIR OVER HYD 7V6786 - Caterpillar

Make reference to GUIDELINE FOR REUSABLE PARTS; PISTONS, Form No. SEBF8049; CYLINDER LINERS, Form No. SEBF8068; and PISTON PINS AND RETAINING RINGS, Form No. SEBF8051. The precombustion chamber (PC) piston and rings have the same specifications as the direct injection (DI) piston and rings. The PC piston has a four slot relief area on the dome of piston for valve clearance. The DI piston has no slots in the piston dome as illustrated. (1) Top ring.(2) Intermediate ring.(3) Oil control ring.(4) Bore in piston for pin ... 50.815 0.008 mm (2.0006 .0003 in.) Clearance between pin and bore in piston ... 0.008 to 0.028 mm (.0003 to .0011 in.)Maximum permissible clearance (worn) ... 0.05 mm (.002 in.)Pin diameter ... 50.795 0.005 mm (1.9998 .0002 in.)7C490 Piston Group (Part of 7C491 Piston & Rod Group)These pistons have an offset pin bore and must be installed correctly in the engine. The word "FRONT" is marked on top of the piston. Also, there is a green color mark on the bottom of the piston. These marks must be toward the front of the engine at installation. Number on tab groove side of connecting rod is to be positioned toward opposite side of engine from camshaft. For PC engines tighten the nut that holds the plug in the piston to a torque of ... 40 7 N m (30 5 lb.ft.)