Valve and Seat Grinding
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- Reconditioning the valve seats is very important. The seating of the valves must be perfect for the engine to deliver optimum power and performance. Several different types of equipment are available for grinding valve seats.
- Another important factor is the cooling of the valve head. Good contact between the valve and the seat will ensure that heat will be properly dissipated.
- The recommendations of the equipment manufacturer should be followed carefully to obtain the proper results. Regardless of the type of equipment used, it is essential that valve guide bores be free of carbon or dirt to ensure proper centering of the tool pilot in the guide.
- Valves that are pitted or have stems that stems that show excessive wear, or valves that are warped excessively must be replaced.
- DO NOT reface valves. Valves with excessive wear or damage MUST be replaced.
- Inspect the valve for the following conditions:
- Burnt or eroded areas (1)
- A worn margin (2)
- A bent stem (3)
- A worn or scored stem (4)
- A worn key groove (5)
- A worn stem tip (6)
- Inspect the valve face for the following conditions:
- Worn or no margin (1 or 4)
- Pitted surfaces (2)
- Burnt or eroded areas (3)
- Inspect the valve margin.
If the margin has worn away, it can lead to breakage, burning or pre-ignition due to heat localizing on this edge. If the vertical edge of the valve head, margin, is not visible and only a sharp edge remains, replace the valve.
- Inspect for a loose valve seat in the cylinder head. 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 equipment manufacturer should be followed carefully to obtain the proper results. Regardless of the type of equipment 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.
- The valve seats should be concentric to the centerline of the guide, measure valve seat runout. The total indicator runout reading must be within specification. Refer to Engine Mechanical Specifications (L83)Engine Mechanical Specifications (L86) .
- If the valve seat has been ground, measure the valve stem height after reassembly of the cylinder head. The cylinder head, and/or valve must be replaced if the valve stem height is not within specification after seat grinding. Refer Engine Mechanical Specifications (L83)Engine Mechanical Specifications (L86) .
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