Reworking valve seats

Special tools and workshop equipment required

• Depth gauge
• Valve seat refacing tool

The max. permissible reworking dimension is calculated as follows:

• Insert valve and press firmly against seat.

• Measure distance between end of valve stem and upper edge of cylinder head.
• Calculate maximum permissible reworking dimension from measured distance and minimum dimension.

Minimum dimension: inlet valve 7.6 mm, exhaust valve 7.6 mm

Measured distance minus minimum dimension = max. permissible reworking dimension.

Example:

2) The max. permissible reworking dimension is shown as dimension “b” in the illustrations for reworking valve seats.

2.2.1 Reworking inlet valve seat

• a = ∅ 28.7 mm
• b = max. permissible reworking dimension ³⁾
• c = 1.5…1.8 mm
• Z = cylinder head lower edge
• α = 45° valve seat angle
• β = 30° upper correction angle
• γ = 60° lower correction angle

3) Calculating max. permissible reworking dimension ⇒ 2.2 Reworking valve seats.

2.2.2 Reworking exhaust valve seat

• a 25.0 mm ∅
• b = max. permissible reworking dimension ⁴⁾
• c = approx.1.8 mm
• Z = cylinder head lower edge
• α = 45° valve seat angle
• β = 30° upper correction angle
• γ = 60° lower correction angle

4) Calculating max. permissible reworking dimension ⇒ 2.2 Reworking valve seats.