Valve Guide Reaming/Valve and Seat Grinding
Valve Guide Reamer
- Measure the valve stem-to-guide clearance using a dial indicator.
Valve stem-to-guide clearance may also be obtained by using a micrometer to
measure the valve stem diameter and a ball type measuring gage to measure the
- A valve stem (1) and guide (2) with clearance in excess
of 0.093 mm (0.0037 in) must be repaired or the components replaced.
- Inspect the valve stems for excessive scoring, wear, or warpage.
- Measure the valve stem diameter. A valve stem with a diameter less
than 7.95 mm (0.313 in) must be replaced. Position the tip of the
dial indicator at the top of the valve guide. If the valve stem diameter is
within specifications, and the stem-to-guide clearance is excessive, the valve
guide must be reamed oversize and a valve with oversize stem installed.
- Ream the valve guide using the J 37378-1 .
- Clean the guide bore of all metal shavings and debris.
- Install the valve (227 and 228), with oversize stem,
into the cylinder head (218).
- Inspect the valve for proper fit. Move the valve back and forth in
the guide. The valve should move freely with no resistance or drag.
- Inspect the valve for the following conditions:
- Inspect the valve face for the following conditions:
- Inspect the valve margin. The exhaust valve may be refaced if the
margin is greater than 1.25 mm (0.05 in) thick before grinding.
- Reface pitted exhaust valves on a suitable valve refacing machine.
- Replace the valve if the margin is less than 1.25 mm
(0.05 in) thick after grinding.
- If the valve face has been ground, it may be necessary to shim the
valve spring to obtain the proper spring installed height. Refer to Cylinder
Head Assemble .
- Inspect for a loose valve seat in the cylinder head (218). The
valve seat has an interference fit to the cylinder head.
- Clean the valve guide bores with a suitable tool. Remove all carbon
or dirt from the bores. The valve guide must be clean for the seat grinding
tool to obtain proper results.
- Grind the valve seat. The recommendations of the manufacturer of
the equipment should be followed carefully to obtain 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 tool pilot
in the guide.
- Inspect the valve seats.