OPERATOR AR 2304956 - Caterpillar

Introduction
The 3406 NSFS Camshafts with cross drilled oil passages, are assembled with either two plugs, or one plug and a screen assembly. Timing advance will not function properly without one of these combinations. A 3406 NSFS Camshaft must be assembled with different parts depending on its intended application. The screen assembly can replace one of the plugs for U.S. on-highway trucks and is used for noise reduction.Necessary Parts
These engines must have either two plugs, or one plug and a screen assembly with orifice to allow the timing advance to function properly. Omitting the plugs causes Serious Engine Damage!
Necessary parts include the 6V-5135 Setscrew and the 7C-2658 Screen Assembly.Adaptability
The 7C-2568 Screen Assembly is used in the following 3406B Truck Engines equipped with injection pump groups; 7C-2616, 7C-3221, 7C-3222, 7C-3223 OR-2876, 0R-2931, 0R-2932, 0R-2933, 0R-2934, 0R-2965. For adaptability see chart.
Illustration 1. 6V-5135 Setscrew (1), 7C-2568 Screen Assembly (2), 3406 Fuel Pump Camshaft (3).The injection pump group part number is stamped on the top face of the injection pump housing. If any of the listed part numbers are found, the 7C-2568 Screen Assembly and one 6V-5135 Setscrew are required. The 7C-2568 Screen Assembly torque is 3 1 N m (27 9 lb in). The 6V-5135 Setscrew Torque is 21 7 N m (16 5 lb ft).
Illustration 2. 6V-5135 Setscrew (1), 6V-5135 Setscrew (2), 3406 Fuel Pump Camshaft (3).For all other 3406 NSFS Injection Pump Groups using camshafts with 7/16 threaded cross drilled oil passages, two 6V-5135 Setscrews are required.