Checking/Refacing Cylinder Head Contact Surface

Reference Sizes: H1
When New: 130.6 / 13O.7 mm (1)
Minimum Height After Stock Removal: 130.4 (1)
Permissible Variation From Evenness Of Mating Surface:
In Longitudinal Direction: 0.08 mm
In Transverse Direction: 0.00 mm
Permissible Variation Of Parallelism Of Top To Bottom Mating Surface:
In Longitudinal Direction: 0.10 mm
Peak-To-Valley Height: 0.003-0.010 mm

Reference Sizes: H2
When new: 145.91 / 146.0 mm
Minimum height after stock removal: 145.7 mm (1)
Permissible Variation From Evenness Of Mating Surface:
In Longitudinal Direction: 0.08 mm
In Transverse Direction: 0.00 mm
Permissible Variation Of Parallelism Of Top To Bottom Mating Surface:
In Longitudinal Direction: 0.10 mm
Peak-To-Valley Height: 0.003-0.010 mm

Reference Sizes: T
With Standard Size Camshaft Bearing, Diameter: 23.07 mm

Test Pressure With Air Under Water
In Bar Gauge: 2 bar

Footnotes
(1) Measure by inserting a shaft and dressing half the diameter. The stock removal at the cylinder head and at the crankcase of an engine must together not be more than 0.40 mm.


NOTE: Only machine cylinder head mating surface if porous or damaged points exist or if an impermissible variation has been measured from the evenness in the longitudinal direction.

CAUTION:
- The top cylinder head mating surface must not be machined otherwise the basic bores of the camshaft bearings will be altered.
- If cracking is suspected (internal loss of coolant), the cylinder head must be pressure-tested.

Refacing
1. Measure reference sizes H1 and H2 and note.
2. Face cylinder head mating surface.
Deburr sharp edges at edge of combustion chamber.
3. Again measure reference sizes H1 and H2.
Determine stock removal and note.
4. Re-position valve seats by the same amount of the stock removal at the cylinder head.
5. Measure reference size (T) between end of valve stem and base of camshaft bearing.

NOTE:
- To do this. insert 0.60 mm round bar in the middle of the bass of the camshaft bearing and measure size "T" with caliper gage.
- If the size obtained is less than the size "T", it is no longer possible to achieve correct valve clearance compensation; replace valve seat ring or cylinder head.

6. Check camshaft timing.

CAUTION:
- It is not permitted to rework the valves.
- If the valve seat has to be reworked, the valve should be replaced.