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Accurate adjustment of the clearance between the valve buttons and the intake and exhaust valves is important if maximum performance and economy are to be obtained. ‪

Intake and exhaust valve clearance are adjusted by an adjusting set screw and locknut located at the valve end of the rocker arm. See Figure 27286 . ‪

Valve and Fuel Injector Height Adjustment Components for the Series 50G Engine

Bar the engine over clockwise until one of the cylinders has the intake and exhaust cam follower rollers on the base circle of the camshaft. Adjust all four valves at this position. Continue barring the engine over until the next cylinder is in position. Follow the timing valve circle chart until all of the valves have been adjusted. See Figure 40399 . ‪

Timing Circle Chart for the Series 50G Engine

  1. Disconnect starting power for engine.
  2. Remove spark plug boots from the connection on the rocker cover.
  3. Remove the engine valve rocker cover; refer to Section .
  4. Insert a 3/4 in. drive breaker bar or ratchet into the square hole in the center of the crankshaft pulley. Bar the engine over until both the intake and exhaust cam rollers are on the base circle of the camshaft. Stop engine rotation.

    Note: The cylinder number.

  5. See Figure 40399 and locate the cylinder. The timing circle can be started with any cylinder. Ensure the circle is completed to set all valves.
  6. To adjust the intake valves, insert a feeler gage between the tip of the valve stem and the valve button at the end of the rocker arm. See Figure 20574 and see Table

    1. Feeler Gage ‪

    4. Wrench (9/16 in.) ‪

    2. Valve Button ‪

    5. Intake Valve Stem ‪

    3. Allen Wrench (3/16 in.) ‪

    Valve Clearance Adjustment Series 50G

  7. Loosen the locknut, and turn the adjusting set screw until the feeler gage produces an even or smooth pull between the valve stem and the valve button.
  8. Torque the locknut to 41-47 Nm (30-35 lbft), and remove the feeler gage. Insert the feeler gage to ensure that the adjustment did not change when the locknut was tightened. Readjust as necessary.
  9. The exhaust valves are adjusted the same way as the intake valves. See Table
  10. Complete the adjustment of all four valves (two intake, two exhaust) for that cylinder before proceeding to the next step.
  11. See Figure 40399 and note the cylinder number, in parentheses, directly under the cylinder that just received the valve adjustment.