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:

• Measured distance
  • 8.0 mm

Minimum dimension

• 7.6 mm

=max. perm. rework dimension¹⁾

• 0.4 mm

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

Reworking inlet valve seat

a = ∅ 28.7 mm b = Max. permissible reworking dimension¹ 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

2) Calculating max. permissible reworking dimension ⇒ 2.3 Reworking valve seats.

Reworking exhaust valve seat

a = 25.0 mm ∅ b = max. permissible reworking dimension¹ 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

3) Calculating max. permissible reworking dimension ⇒ 2.3 Reworking valve seats.