Cylinder Head Measurement and Reconditioning
SPECIAL TOOLS- Seat Cutter tool No. 115 8280, or equivalent
- Valve Clamp Mandrel tool No. 951 2051, or equivalent
- Valve Spring Clamp tool No. 998 6052, or equivalent
- Puller tool No. 999 5219, or equivalent
- Gauge tool No. 999 5222, or equivalent
- Fixture tool No. 999 5363, or equivalent
- Drift tool No. 999 5364, or equivalent
- Drift tool No. 999 5365, or equivalent
- Reamer tool No. 999 5373, or equivalent
- Drift tool No. 999 5379, or equivalent
- Drift tool No. 999 5505, or equivalent
- Spring tester tool No. 999 9802, or equivalent
PROCEDURE
1. Remove tappets (valve lifters) from cylinder head
- Use magnet or suction cup to assist in removing tappets.
- Check tappets for signs of wear. Measure as required.
NOTE:
^ Store tappets upside down to prevent oil draining out.
^ Ensure tappets are placed in order - do not interchange components.
^ Put tappets in oil-filled container if storing for any length of time.
Tappet dimensions
A = External diameter: 32.00 mm (+0.025/-0.041 mm)
B = External height: 26.00 ± 0.50 mm
Distance between top of tappet and piston
C-1 = Unloaded: 18.40 mm
C-2 = Compressed: 16.15 mm (+0.30/-0.10 mm)
2. Remove valves
Use valve spring clamp tool No. 998 6052 and clamp mandrel tool No. 951 2051, or equivalents.
Remove:
- valve collets
- upper spring collars
- valve springs
- valves
NOTE: Check positions of moving parts carefully.
3. Remove valve stem seals
Use puller tool No. 999 5219, or equivalent.
Remove seals and lower spring collars.
Clean cylinder head:
- joint faces
- combustion chambers
- intake/exhaust ports
- valve seats
4. Check cylinder head
- Clean spark plug socket threads (use 14x1.25 mm tap)
- Clean valves, valve springs and spring collars.
- Check visually for damage.
- If in doubt as to whether valve seats are cracked, mill seat clean using seat cutter tool 115 8280, or equivalent, with 07 mm spindle and 45° cutter.
NOTE: Check that the reaming tool does not come into contact with the combustion chamber walls.
Cleaning air intake ducts: (if equipped)
- Scrape hole clean (4 mm) as far as possible.
- Blow air intake ducts clean with compressed air from intake side, on top of cylinder head.
- Check that air is getting through.
Valve seat width
Intake: 1.40-1.80 mm
Exhaust: 1.80-2.20 mm
5. Measure cylinder head distortion
- Use steel rule and feeler gauges.
Max. distortion
Longitudinal: 0.50 mm
Lateral: 0.05 mm
Cylinder head height: 129.00 ± 10.05 mm
Max. machining allowance: 0.30 mm
NOTE: Only machine cylinder head to remove scoring or corrosion on joint faces if head is undistorted.
6. Measure valve guide wear:
- Use magnetic stand and dial gauge.
- Lift valve approx. 2-3 mm clear of seat when checking guide.
Clearance between new components:
Intake: 0.03-0.06 mm
Exhaust: 0.04-0.07 mm
Max. clearance, used components:
Intake: 0.15 mm
Exhaust: 0.15 mm
7. Measure valve springs
External diameter: 0.15 mm
Internal diameter: 26.20 mm
Measure spring load using tester tool No. 999 9802, or equivalent.
Length (mm) and Load (N)
L: 42.00 mm - No Load
L1: 34.00 mm - 270 ± 20 N
L2: 24.50 mm - 640 ± 40 N
8. Valve measurement
A = Valve head diameter
Intake: 31.00 ± 0.15 mm
Exhaust: 27.00 ± 0.15 mm
B = Valve stem diameter
Intake: 6.97 mm (+0.00/-0.015 mm)
Exhaust: 6.97 mm (+0.00/-0.015 mm)
C = Overall length
Intake: 104.05 ± 0.18 mm
Exhaust: 103.30 ± 0.18 mm
Max. machining allowance, valve stem: 0.40 mm
D = Height of valve head
Intake/exhaust: 1.50 mm
Min. height after grinding: 1.20 mm
E = Sealing face angle
Intake: 44.50°
Exhaust: 44.50°
Valve Guides, Replacement
9. Mount cylinder head on fixture tool No. 999 5363, or equivalent
- Adjust angle of inclinations using holes at top of fixture ends.
- Clamp head to fixture using any of the holes so that the drift is vertical when pressed in.
- Use four sleeves as spacers for cylinder head bolts.
- Press out guides to be replaced
Press Out Guides To Be Replaced
10. Press out guides using drift tool No. 999 5364, or equivalent
- Press slowly until drift bears against valve spring seat.
- Remove any metal clips if guide is damaged.
11. Press down further using drift 999 5365
- Inspect upper section of guide bore.
- Oversize guide must be installed if guide bore is scored. (See step 14 below.)
12. Place new valve guide on drift tool No. 999 5505, or equivalent, and press home
- Press guide slowly into head until drift bears against valve spring seat.
- Top of guide should project by: 13.00 ± 0.20 mm
- Height is set by tool.
NOTE:
^ Pressure should be at least 9000 N.
^ If less force is required, remove guide, ream out bore and install oversize guide.
13. Valve guides, markings and dimensions
Standard
Diameter: 12.00 mm
No. of grooves: 0
Oversize, No. 1
Diameter: 12.10 mm
No. of grooves: 1
Oversize, No. 2
Diameter: 12.20 mm
No. of grooves: 2
14. To install oversize guide, ream out hole with reamer tool No. 999 5373, or equivalent
NOTE:
^ Reamers come in two sizes (oversize 1 and 2)
^ Oversize No. 1 can often be pressed home without reaming.
Dressing Valve Seats
15. Mill valve seats
Angles:
Sealing face angle, intake/exhaust: 45°
Relief angle, upper: 15°
Relief angle, lower: 60°
Valve seat width: (dimension a)
Intake: 1.40-1.80 mm
Exhaust: 1.80-2.20 mm
NOTE: Check that milling cutter is clear of combustion chamber walls.
Dressing Valves
16. Grind intake valves
Seating face angle: 44.5°
Edge width, new valve: 1.50 mm
Min. edge width aver grinding: 1.20 mm
NOTE: Exhaust valves are stellite coated and must be ground only with grinding paste (by hand).
17. Check valve stem height
- Use gauge tool No. 999 5222, or equivalent.
- Place gauge across camshaft bearing seats.
- Measure valve stem height by inserting sliding calipers through hole in gauge.
Valve stem height: 48.50 ± 0.40 mm
Max. machining allowance, valve stem: 0.40 mm
Length, new valve
Intake: 104.50 ± 0.18 mm
Exhaust: 103.30 ± 0.18 mm
NOTE: Correct valve stem height is essential if the hydraulic tappets are to work properly.
Valves, Installation
18. Grease valve stems and guides.
- Install valves:
- lower valve spring collars
- valves (in correct positions)
- Mount protective sleeve (included in gasket kit) on valve stem.
19. Install valve stem seals
- Place seal on valve stem.
- Remove protective sleeve.
- Push seal onto stem by hand only as far as possible. Use drift tool No. 999 5379, or equivalent.
CAUTION: Do not use a hammer to fit valve stem seals, otherwise damage may result.
20. Install
- valve spring and upper spring collar using valve spring clamp tool No. 998 6052 and clamp mandrel tool No. 951 2051, or equivalents.
- Collets: check that both halves are properly in position when the spring is not under load.