Engine Inspection and Repair
CYLINDER HEAD
1. Inspect cylinder head for damage, cracks and leakage of water or oil, replacing as necessary.
2. Measure cylinder head distortion. If distortion exceeds .004 inch (.1 mm), grind cylinder head surface. Grinding limit is .006 inch (.15 mm).
3. If cylinder head height is not 4.931-4.935 inches (125.25-125.35 mm), replace it.
4. Measure manifold contact surface distortion. If distortion exceeds .004 inch (.1 mm), grind surface or replace cylinder head.
VALVE & VALVE GUIDE
1. Inspect valve for damaged or bent stem, roughness or damage to face, or damage or uneven wear of stem tip, replacing as necessary.
2. Check valve head margin thickness which should be .03-.049 inch (.75-1.25 mm) for intake valve or .047-.071 inch (1.2-1.8 mm) for exhaust valve.
3. Measure valve length, which should be 4.776 inch (121.31 mm) for intake valve or 4.828 inch (122.63 mm) for exhaust valve.
4. Measure valve stem diameter, which should be .2744-.2750 inch (6.97-6.985 mm) for intake valve or .3159-.3165 inch (8.025-.804 mm) for exhaust valve.
5. Measure valve guide inner diameter, which should be .276-.2768 inch (7.01-7.03 mm) for intake valve or .3177-.3185 inch (8.07-8.09 mm) for exhaust valve.
6. Measure valve stem to guide clearance, which should be .001-.0024 inch (.025-.06 mm) for intake valve or .0012-.0026 inch (.030-.065 mm) for exhaust valve. If clearance exceeds .0079 inch (.2 mm), replace valve and/or valve guide.
7. To replace valve guide, proceed as follows:
a. Gradually heat cylinder head in water to 190°F.
b. Using tool 490249010A or equivalent, remove valve guide from side opposite combustion chamber, then remove valve guide clip.
c. Install clip onto valve guide and, with cylinder head heated to 190°F, tap valve guide in from side opposite combustion chamber until clip contacts cylinder head.
Fig. 3 Checking valve guide protrusion:
8. Check that height A, Fig. 3, is .52-.543 inch (13.2-13.8 mm) for intake valve or .772-.795 inch (19.6-20.2 mm) for exhaust valve.
VALVE SEAT
1. Inspect contact surface of valve seat and the valve face for roughness or damage. If necessary, resurface valve seat with a 45° valve seat cutter and/or resurface valve face.
2. Apply a thin coat of prussian blue to valve face.
3. Check valve seating by rotating the valve against the seat. If blue does not appear 360° around valve face, replace valve. If blue does not appear 360° around valve seat, resurface valve.
4. Check seat contact width, which should be .047-.063 inch (1.2-1.6 mm).
5. Check that valve seating position is at center of valve face. If valve seating position is too high, correct with a 65° cutter. If valve seating position is too low, correct with a 35° cutter for intake valve or 15° cutter for exhaust valve.
6. Seat valve to valve seat with a lapping compound.
Fig. 4 Checking sinking of valve seat:
7. Check sinking of valve seat, by measuring protruding length L, Fig. 4. If L is 2.008-2.047 inch (51-52 mm) for intake valve or 1.969-2.008 inch (50-51 mm) for exhaust valve, insert a spacer between spring seat and cylinder head to adjust. If L exceeds 2.047 inch (52 mm) for intake valve or 2.008 inch (51 mm) for exhaust valve, replace cylinder head.
Fig. 5 Valve spring specification chart:
VALVE SPRING
1. Inspect each valve spring for cracks or damage.
2. Check spring free length and angle, Fig. 5, replacing as necessary.
CAMSHAFT
1. Set front and rear journals on V-blocks and check camshaft runout. If runout exceeds .0012 inch (.03 mm), replace camshaft.
2. Check camshaft for wear or damage, replacing as necessary.
Fig. 6 Checking cam lobe height:
3. Check cam lobe height at two points, Fig. 6. Height should be 1.6163 inch (41.054 mm) and must not be less than 1.608 inch (40.854 mm) for intake, or should be 1.6257 inch (41.293 mm) and must not be less than 1.6178 inch (41.093 mm) for exhaust.
Fig. 7 Measuring camshaft journal diameters:
4. Measure journal diameters in X and Y directions at two points, Fig. 7. Diameter of Nos. 1 and 4 should be 1.9268-1.9274 inch (48.94-48.955 mm) and diameter of Nos. 2 and 3 should be 1.9258-1.9266 inch (48.915-48.935 mm). Out of round must not exceed .0012 inch (.03 mm).
5. Measure camshaft and cylinder head oil clearance as follows:
a. Remove any oil or dirt from journals and the camshaft bore.
b. Measure camshaft bore diameter, which should be 1.9297-1.9303 inch (49.015-49.03 mm).
c. Subtract journal diameter from bore diameter. Oil clearance of Nos. 1 and 4 should be .0024-.0035 inch (.06-.09 mm) and Nos. 2 and 3 should be .0031-.0045 inch (.08-.115 mm).
d. If clearance exceeds ,0059 inch (.15 mm), replace camshaft or cylinder head.
6. Measure camshaft endplay, which should be .002-.0071 inch (.05-.18 mm).
7. If endplay exceeds .0079 inch (.2 mm), replace thrust plate or camshaft.
ROCKER ARM & ROCKER SHAFT
1. Check for wear or damage to contact surface of rocker arm shaft and rocker arm, replacing as necessary.
2. Check oil clearance between rocker arm and shaft as follows, replacing as necessary.
a. Measure rocker arm inner diameter, which should be .748-.7493 inch (19-19.033 mm).
b. Measure rocker arm shaft diameter, which should be .7464-.7472 inch (18.959-18.98 mm).
c. Subtract shaft diameter from rocker arm diameter. Oil clearance should be .0008-.0029 inch (.02-.074 mm).
d. If clearance exceeds .0039 inch (.1 mm), replace rocker arm and/or shaft as necessary.
HYDRAULIC LASH ADJUSTER
Check face of hydraulic lash adjuster for wear or damage, replacing as necessary. Do not remove adjuster unless necessary.
CYLINDER BLOCK
1. Check cylinder block for leakage damage, cracks or scoring of walls, repairing or replacing as necessary.
2. Measure distortion of top surface of cylinder block. If distortion exceeds .006 inch (.15 mm), grind to a maximum of .008 inch (.2 mm), or replace cylinder block.
Fig. 8 Measuring cylinder bore:
3. Measure cylinder bore in X and Y directions at three levels in each cylinder, Fig. 8. If cylinder bore is not 3.5433-3.5442 inch (90-90.22 mm), rebore cylinder to oversize of .01 or .02 inch (.25 or .5 mm).
4. If difference between top and bottom measurements exceeds .0007 inch (.019 mm), rebore cylinder to oversize.
5. If out of round exceeds .0007 inch (.019 mm), rebore cylinder to oversize. Boring size should be based on the size of an oversize piston and the same for all cylinders.
6. If upper part of cylinder wall shows uneven wear, remove ridge using ridge reamer.
PISTONS, RINGS & PINS
1. Inspect outer circumferences of all pistons for seizure or scoring, replacing as necessary.
2. Measure outer diameter of each piston at right angle to piston pin, .87 inch (22 mm) below oil ring land lower edge. Piston diameter should be 3.5411-3.5419 inches (89.944-89.964 mm). Pistons are available in .01 and .02 inch (.25 and .5 mm) oversize.
3. Check piston to cylinder clearance, which should be .0019-.0026 inch (.049-.065 mm). If clearance exceeds .0059 inch (.15 mm), replace piston or rebore cylinders to fit oversize pistons. Whenever replacing pistons, use new piston rings.
4. Measure piston ring to ring land clearance around entire circumference with new piston ring. Clearance should be .001-.003 inch (.03-.07 mm). If clearance exceeds .006 inch (.15 mm), replace piston.
5. Inspect piston rings for damage, abnormal wear or breakage, replacing as necessary.
6. Insert piston ring into cylinder by hand and use piston to push it to bottom of ring travel.
7. Measure each piston ring end gap. If end gap exceeds .039 inch (1 mm), replace ring(s).
8. Measure piston pin hole diameter, which should be .905-.9055 inch (22.988-23 mm).
9. Measure piston pin diameter, which should be .9045-.9047 inch (22.974-.2298 mm).
10. Check piston pin to piston clearance. If clearance is not .0003-.001 inch (.008-.026 mm), replace piston and/or pin.
CONNECTING ROD
1. Measure connecting rod small end bore, which should be .9033-.904 inch (22.943-22.961 mm).
2. Check interference between small end bore and piston pin, which should be .0005-.0015 inch (.013-.037 mm).
3. Check each connecting rod for bending or twisting. If bend or twist exceeds .0024 inch (.06 mm), repair or replace as necessary.
CRANKSHAFT
1. Check journals and pins for damage, scoring or oil hole clogging.
2. Set crankshaft on V-blocks and check crankshaft runout at center journal. If runout exceeds .0016 inch (.04 mm), replace crankshaft.
Fig. 9 Measuring crankshaft journal diameters:
3. Measure each journal diameter in X and Y direction at two points, Fig. 9. Main journal diameter should be 2.4385-2.4392 inch (61.937-61.955 mm) and crankpin journal diameter should be 2.0842-2.0848 inch (52.94-52.955 mm). Out of round must not exceed .002 inch (.05 mm).
4. If diameter is less than minimum, grind journal to match undersize bearing, which is available in .01 inch (.25 mm) undersize. Do not grind rolled fillet area.
MAIN & CONNECTING ROD BEARINGS
Check bearings for peeling, scoring or other damage, replacing as necessary.
TIMING BELT
Replace timing belt if there is any oil or grease on it. Check timing belt for damage, wear, peeling, cracks or hardening, replacing as necessary. Never forcefully twist or turn inside out and be careful not to allow oil or grease on belt.
TIMING BELT AUTO TENSIONER
1. Check tensioner pulley for smooth rotation and abnormal noise, replacing as necessary. Do not clean pulley with cleaning fluids. If necessary, use a soft rag to wipe clean and avoid scratching pulley.
2. Check auto tensioner for oil leakage, replacing as necessary.
3. Check tension rod projection free length, which should be .47-.55 inch (12-14 mm). Replace as necessary.
TIMING BELT & CAMSHAFT PULLEYS
Inspect pulley teeth for wear, deformation or other damage, replacing as necessary. Do not clean pulley with cleaning fluids. If necessary, use a soft rag to wipe clean, being careful not to scratch pulley.
TIMING BELT COVER
Inspect timing belt covers for damage or cracks, replacing as necessary.