Valves, valve springs and guides

inspection

1. Clean cylinder head, valve springs, valves and valve guide bores.
2. Check existing valve stem and head diameters.
3. Check valve stem to guide clearance using new valves.

4. Renew valves and guides as necessary.

Valve head diameter A:
Inlet = 39.75 to 40.00 mm
Exhaust = 34.226 to 34.48 mm
Valve stem diameter B:
Inlet = 8.664 to 8.679 mm
Exhaust = 8.651 to 8.666 mm

5. Check installed height of each valve. Valve installed height C= 47.63 mm
6. Renew valve/valve seat insert as necessary.

7. Check valve stem to guide clearance.
Valve stem to guide clearance D:
Inlet = 0.25 to 0.66 mm
Exhaust = 0.38 to 0.78 mm

8. Check condition of valve springs:
Free length = 48.30 mm
Fitted length = 40.40 mm
Load at fitted length = 339 ± 10N
Load at valve open length = 736 ± 22N

Note: Valve springs must be replaced as a complete set.

Valve guide - renew

1. Using valve guide remover, LRT-12-037 press valve guide out from combustion chamber side of cylinder head.

NOTE: Service valve guides are 0.025mm oversize on outside diameter to ensure interference fit.

2. Lubricate new valve guide with engine oil and place in position.

3. Using LRT-12-038 partially press guide into cylinder head, remove tool.
4. Fit LRT-12-515 over valve guide and continue to press guide into cylinder head until tool contacts spring seat. Remove tool.
Valve guide installed height A = 24.13 mm

Valve seat insert - renew

NOTE: Service valve seat inserts are available 0.25 mm oversize on outside diameter to ensure interference fit.

1. Grind a crescent in seat insert, until thin enough to break using a cold chisel.

CAUTION: Do not damage counterbore.

2. Heat cylinder head evenly to approximately 65°C.
3. Using a suitable mandrel, press new insert fully into counterbore.
4. Allow cylinder head to air cool.

Valve seats - renew

1. Check condition of valve seats and valves that are to be reused.
2. Remove carbon from valves and valve seats.
3. Reface valves as necessary. If a valve has to be ground to a knife-edge to obtain a true seat, fit a new valve.
Valve seating face angle A = 45°

4. Cut valve seats using LRT-12-501 with LRT-12-503 and LRT-12-504.
Valve seat:
Width A: Inlet = 37.03 mm
Exhaust = 31.50 mm
Width B = 1.5 - 2.00 mm
Angle C = 70°
Angle D = 46° ± 15’
Angle E = 20°

 

5. Ensure cutter blades are correctly fitted to cutter head with angled end of blade downwards, facing work, as illustrated. Check that cutter blades are adjusted so that middle of blade contacts area of material to be cut.
Use light pressure and remove only minimum of material necessary.

Valves and springs - refit

1. Lap each valve to its seat using fine grinding paste.
2. Clean valve and seat.

3. Coat valve seat with a small quantity of engineers blue, insert valve and press it into position several times without rotating. Remove valve and check for even and central seating.

Seating position shown by engineers blue should be in centre of valve face.
4. Check valve installed height if valve seats have been recut or new valves or valve seat inserts have been fitted.
Valve installed height A = 47.63 mm

5. Thoroughly clean cylinder head, blow out oilways and coolant passages.
6. Fit new valve stem oil seals, lubricate valve stems, fit valves, valve springs and caps, compress valve springs using LRT-12-034 and fit collets.

7. Using a wooden dowel and mallet, lightly tap each valve stem two or three times to seat valve cap and collets.

For refitting the cylinder heads see the "cylinder head" page.