Disassembly and Assembly

The cylinder heads have integral valve guides and valve seats. The seats can be re-ground. Seats that have been previously re-ground can be replaced with service seats. Service valve guides are also available to replace worn valve guide bores.

CAUTION: Seats that have been previously re-ground should be marked as illustrated.

DISASSEMBLY OF THE CYLINDER HEAD





CAUTION: Mark the valves to identify their position.





Compress the valve springs and remove the valve stem collets.





Release valve spring and remove the retainer and spring.





Remove the remaining collets, retainers, springs and valves.

CAUTION: Keep the valves in a labeled rack.





Remove the valve stem seals.





CLEANING AND INSPECTING THE CYLINDER HEAD

Clean the carbon from the injector nozzle seat with a nylon or brass brush.





Scrape the gasket residue from all gasket surfaces.





Wash the cylinder head in hot soapy water solution. After rinsing, use compressed air to dry the cylinder head.





Polish the gasket surfaces with 400 grit paper.

Use an orbital sander or sanding block to maintain a flat surface.





Inspect the valve guides for scuffing or scoring. Measure the valve guide bore.

Diameter mm in

MIN 8.019 0.3157
MAX 8.089 0.3185

NOTE: If the valve guide bore is over the maximum limit, refer to Engine Alternative Repair Procedures





Inspect the head surface for nicks, erosion, etc. Check for head distortion as illustrated.

Limit

Variation: 0.010mm [0.0004 inch] within a 50.8mm [2.0 inch] diameter area, 0.30 [0.012 inch] overall end to end or side to side.

NOTE: If the cylinder head deck surface is out of specification, refer to Cylinder Block Repair Procedures.

CLEANING AND INSPECTING THE VALVES





Clean the valve heads with a soft wire wheel.





Polish the valve stems with crocus cloth.





CAUTION: Re-mark the valves according to head location.





Inspect for abnormal wear on the valve heads and stems. Measure the valve stem diameter.

Diameter mm in

MIN 7.935 0.3126
MAX 7.960 0.3134





CAUTION: Mark the new valves, if required, for the replacement location.

GRINDING THE VALVES





Grind the face of valves to be reused. Check for and replace bent valves.





Seat Angle:
Intake: 30 Degrees
Exhaust: 45 Degrees





Measure rim thickness.

Limit:
Minimum (T): 0.79mm [0.031 inch]





Check the valve stem tip for flatness.





If required. resurface the tip.

GRINDING THE SEATS





CAUTION: The illustrated marks indicate valve seats have been ground previously.

Replacement valve seat inserts must be installed if the valve seats have been ground previously.

CALCULATING THE GRINDING DEPTH





Install the valves in their designated location and measure the valve depth.





CAUTION: The valve depth is the distance from the valve face to the head deck.

Record the depth of each valve as (A).

Valve Depth mm in

MIN 0.99 0.039
MAX 1.52 0.060





Grind the valve seats to remove scores, scratches and burns.





Seat Angle:

Intake: 30 Degrees
Exhaust: 45 Degrees





Install the valves in their respective bores and measure the depth again.





Record the depth of each valve as (B).

Calculate grinding depth (GD) as follows:

GD=(B)-(A)





Limit:

GD: 0.254mm [0.010 inch]

NOTE: Service valve seats are available for seats that are over the limit.





CAUTION: Mark the cylinder head to identify the re-ground valve seats.





Install the valves in their designated location and measure the depth.





Check valve depth (C) (Integral and insert valve seats).

Valve Depth mm in

MIN 0.99 0.039
MAX 1.52 0.060

CAUTION: Replace the valve if the depth is over the limit.





Apply a light coat of valve lapping compound to each valve and lap each valve to its companion seat.





Remove the valves and clean the lapping compound from the valves and seats.





Measure the valve seat width indicated by the lapped surface.

Valve Seat Width Limit:

Minimum (1): 1.5mm [0.060 inch]
Maximum (2): 2.0mm [0.080 inch]





If required, grind area (A) with a 60 degree stone and (B) with a 15 degree stone to center the seat on the valve face. Maintain the valve seat width limits.

Minimum (1): 1.5mm [0.060 inch]
Maximum (2): 2.0mm [0.080 inch]





INSPECT THE VALVE SPRINGS

Measure the valve spring.

Limits:

Approximate Free Length (L): 55.63mm [2.190 inch]
Maximum Inclination: 1.0mm [0.039 inch]





MEASURE VALVE SPRING FORCE

Force Required:

289.32 N [65 lbs] is the minimum acceptable load required to compress the spring to a height of 49.25 mm [1.94 inch].





ASSEMBLY OF THE CYLINDER HEAD

NOTE: Clean all cylinder head components before assembling.

Install the valve stem seals.

NOTE: The intake and exhaust seals are the same.





Lubricate the stems with SAE 90W oil before installing the valves.





Compress the valve spring after assembling the spring and retainer.





Install new valve collets and release the spring tension.





WARNING: Wear protective equipment and do not stand in line with the valve stem when tapping the valve.

After assembly, tap the valve stems to verify the collets are seated.