L

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(c) Check the valve head margin thickness.

Standard margin thickness: 0.8 - 1.2 mm

Minimum margin thickness: 0.5 mm (0.020 in.)

If the margin thickness is less than minimum, replace the valve.

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(d) Check the valve overall length.

Standard overall length:

Intake 100.60 mm (3.9606 in.) Exhaust 100.45 mm (3.9547 in.)

Minimum overall length:

Intake 100.1 mm (3.941 in.) Exhaust 100.0 mm (3.937 in.)

If the overall length is less than minimum, replace the valve.

(e) Check the surface of the valve stem tip for wear.

If the valve stem tip is worn, resurface the tip with a grinder or replace the valve.

NOTICE: Do not grind off more than the minimum.

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8. INSPECT AND CLEAN VALVE SEATS

(a) Using a 45° carbide cutter, resurface the valve seats. Remove only enough metal to clean the seats.

(b) Check the valve seating position.

Apply a thin coat of prussian blue (or white lead) to the valve face. Lightly press to the valve against the seat. Do not rotate the valve.

(c) Check the valve face and seat for the following:

• If blue appears 360° around the face, the valve is concentric. If not, replace the valve.

• If blue appears 360° around the valve seat, the guide and face are concentric. If not, resurface the seat.

• Check that the seat contact is in the middle of the valve face with the following width:

If not, correct the valve seats as follows:

(1) If the seating is too high on the valve face, use 30° and 45° cutters to correct the seat.

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(2) If the seating is too low on the valve face, use 75° and 45° cutters to correct the seat.

Squareness

(d) Hand-lap the valve and valve seat with an abrasive compound.

(e) After hand-lapping, clean the valve and valve seat.

Squareness em0988

INSPECT VALVE SPRINGS

(a) Using a steel square, measure the squareness of the valve spring.

Maximum squareness: 2.0 mm (0.075 in.)

If squareness is greater than maximum, replace the valve spring.

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(b) Using vernier calipers, measure the free length of the valve spring.

If the free length is not as specified, replace the valve spring.

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(c) Using a spring tester, measure the tension of the valve spring at the specified installed length.

Installed tension:

16.7 - 19.3 kg (36.8 - 42.5 lb, 164 - 189 N) at 34.7 mm (0.000 in.)

If the installed tension is not as specified, replace the valve spring.

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10. INSPECT CAMSHAFTS AND BEARINGS

A. Inspect camshaft for runout

(a) Place the camshaft on V-blocks.

(b) Using a dial indicator, measure the circle runout at the center journal.

Maximum circle runout: 0.04 mm (0.0016 in.)

If the circle runout is greater than maximum, replace the camshaft.

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B. Inspect cam lobes

Using a micrometer, measure the cam lobe height.

Standard cam lobe height:

Intake 35.310 - 35.410 mm (1.3902-1.3941 in.) Exhaust 35.560 - 35.660 mm (1.4000-1.4039 in.)

Minimum cam lobe height:

Intake 35.20 mm (1.3858 in.) Exhaust 35.45 mm (1.3957 in.)

If the cam lobe height is greater than minimum, replace the camshaft.

C. Inspect camshaft journals

Using a micrometer, measure the journal diameter.

Journal diameter: 26.959 - 26.975 mm (1.0614-1.0620 in.)

If the journal diameter is not as specified, check the oil clearance.

D. Inspect camshaft bearings

Check the bearings for flaking and scoring.

If the bearings are damaged, replace the bearing caps and cylinder head as a set.

Free Distance

Free Distance

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E. Inspect camshaft gear spring

Using vernier calipers, measure the free distance between the spring end.

If the free distance is not as specified, replace the gear spring.

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F. Inspect camshaft journal oil clearance

(a) Clean the bearing caps and camshaft journals.

(b) Place the camshafts on the cylinder head.

(c) Lay a strip of Plastigage across each of the camshaft journals.

(d) Install the bearing caps.

(See step 4 on pages EM-123 to 125)

NOTICE: Do not turn the camshaft.

(e) Remove the bearing caps.

(f) Measure the Plastigage at its widest point.

Standard oil clearance: 0.025 - 0.062 mm

Maximum oil clearance: 0.10 mm (0.0039 in.)

If the oil clearance is greater than maximum, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.

(g) Completely remove the Plastigage.

G. Inspect camshaft thrust clearance

(a) Install the camshafts.

(See step 4 on pages EM-123 to 125)

(b) Using a dial indicator, measure the thrust clearance while moving the camshaft back and forth.

Standard thrust clearance:

Maximum thrust clearance:

Intake 0.12 mm (0.0047 in.) Exhaust 0.10 mm (0.0039 in.)

If the thrust clearance is greater than maximum, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.

H. Inspect camshaft gear backlash

(a) Install the camshafts without installing the exhaust cam sub-gear.

(See step 4 on page EM-123 to 125)

(b) Using a dial indicator, measure the backlash.

Standard backlash: 0.020 - 0.200 mm

Maximum backlash: 0.30 mm (0.0188 in.)

If the backlash is greater than maximum, replace the camshafts.

11. INSPECT VALVE LIFTERS AND LIFTER BORES

(a) Using a caliper gauge, measure the lifter bore diameter of the cylinder head.

Lifter bore diameter: 28.000 - 28.021 mm

(b) Using a micrometer, measure the lifter diameter.

Lifter diameter: 27.975 - 27.985 mm (1.1014-1.1018 in.)

(c) Subtract the lifter diameter measurement from the lifter bore diameter measurement.

Standard oil clearance: 0.015 - 0.046 mm

Maximum oil clearance: 0.07 mm (0.0028 in.)

If the oil clearance is greater than maximum, replace the lifter. If necessary, replace the cylinder head.

12. INSPECT INTAKE AND EXHAUST MANIFOLDS

Using precision straight edge and feeler gauge, measure the surface contacting the cylinder head for warpage.

Maximum warpage: 0.30 mm (0.0118 in.)

If warpage is greater than maximum, replace the manifold.

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