Valve Seat Grinding Reconditioning the valve seats is very important. The seating of the valves must be perfect for the engine to deliver the power and performance it was designed to produce. Another important factor is the cooling of the valve head. Good contact between each valve and its seat will ensure that heat will be carried away properly. Several different types of equipment are available for refacing valves. The manufacturer's instructions for how to use the equipment should be carefully followed to attain the proper results.
Regardless of what type of equipment is used, it is essential that valve guide bores be free from carbon or dirt to ensure proper centering of the pilot in the guide. Refer to “Specifications” for valve seat angle specifications. Reaming Valve Guide The valve guides used in this engine are simply holes bored in the cylinder head. The valve guides are not replaceable. If the valve stem-to-bore clearance as previously measured is excessive, the valve guides should be reamed and a valve with an oversize stem installed. Oversize valves are available. Refer to “Specifica- tions”. Select a reamer that will provide a straight, clean bore through the entire length of the valve guide (figure 12-58).
Valve Rocker Arm Stud Replacement Remove or Disconnect 1 . Valve rocker arm stud by unscrewing. Install or Connect 1 . Valve rocker arm stud into cylinder head. Tighten • Rocker arm stud to 47 N m (35 lb· ft.). Figure 12-58 Reaming Valve Guides Assembly Figures 12-48, 12-49, 12-59 and 12-60 Install or Connect 1 . Valves. A . Lubricate the valve stems with clean engine oil. B . Insert the valves into the proper valve guides until the face of the valve contacts the valve seat. 2 . Seal. A . Install the seal over the valve stem. B . Hold the valve against the valve seat. C . Push the seal down the valve stem until it bottoms out against the head. 3 . Springs. 4 . Valve spring cap. A .
Compress the valve spring using J 8062 (figure 12-48), enough so the lower valve stem groove can be seen clearly. B . Apply a small amount of grease to the area of the upper valve stem groove. C . Assemble the two valve keys into the upper groove using the grease to hold them in place. D . Release the compressor tool J 8062, making sure the valve keepers stay in place. E . Repeat the preceding steps on the remaining valves. G643 (E) Service Manual Chapter 3. Engine Mechanical System 89