Valve Clearance: Adjustments
Valve Clearance, Check and Adjust
- Remove camshaft cover.
- Rotate the engine as necessary to measure the valve clearances between the heel of the cam and the cam follower (Fig. 1). See Specifications for the correct valve clearances.
- Make a note of each clearance measurement.
- Should the clearances be incorrect, proceed as follows:
- Rotate the engine and set No.1 cylinder at TDC using Service Tool 18G 1433A (1 Fig. 2).
- Push back the lock tabs (1 Fig. 3) from the camshaft sprocket securing bolts (2 Fig. 3).
- Slacken off the bolts and tab washers.
- Remove the upper chain tensioner valve clamp bolt (3 Fig. 3), remove the clamp (4 Fig. 3) and remove the valve (5 Fig. 3).
- Using a 3 mm Allen key, wind back the tensioner (turn clockwise) until the snail engages in the park position.
- Remove the tensioner housing securing bolt (7 Fig. 3) and remove the tensioner assembly (8, 9 Fig. 3).
- Remove and discard the `O' ring (9 Fig. 3) and gasket (10 Fig. 3).
- Remove the camshaft sprocket securing bolts/tab washers (1, 2 Fig. 3) and remove the sprockets (11 Fig. 3).
- Remove the cylinder head bolt from No.2 cap, left-hand camshaft (1 Fig. 4).
- Remove the cap securing bolts from No.2 cap, left-hand camshaft.
- Remove No.2 cap from the left-hand camshaft.
- Fit spacer tool 18G 1435 (2 Fig. 4) to the head.
- Fit and torque tighten the cylinder head bolt.
- Repeat the procedure for Nos 3, 4, 5 and 6 caps, left-hand camshaft (3 Fig. 4).
- Remove the cylinder head bolt from No.7 cap, left-hand camshaft.
- Loosen in sequence the securing bolts from Nos 1 and 7 caps, until the left-hand camshaft is free. Lift the camshaft from the cylinder head and fit spacer tool 18G 1435 to No. 7 cylinder head bolt position (5 Fig. 4). Fit and torque tighten the bolt.
- Repeat the procedure for the right-hand camshaft.
CAUTION: The cylinder head bolts MUST be renewed during assembly and torque tightened as described under Engine, Service and Repair, Service Procedures, SPS Joint Control System.
Remove all the valve shims or only those requiring adjustment, check the size of the existing shims with a micrometer and note the reading. Calculate the size of the shim required following the examples shown below:
VALVE CLEARANCES
For valve clearances see Specifications
Excessive Clearance in Inches
Size of existing shim 00.100
Plus the actual clearance noted 0.019 = 0.119
Less the specified valve clearance 0.013
Required shim size = 0.106
Insufficient Clearance in Inches
Size of existing shim 0.107
Plus the actual clearance noted 0.010 = 0.117
Less the specified valve clearance 0.013
Required shim size = 0.104
Fit the relevant shims to the cylinder head.
Note: See Service Data under Engine Specifications for available valve shim sizes.
- Fit the left-hand camshaft at approximately TDC.
- Lubricate Nos 1 and 7 caps.
- Fit No 1 cap. Fit but do not tighten the cap securing bolts.
- Remove No 7 cap cylinder head bolt.
- Remove the spacer tool.
- Fit No.7 cap. Fit but do not tighten the cap securing bolts.
- Finally tighten Nos 1 and 7 cap securing bolts in sequence.
- Remove No.4 cap cylinder head bolt and remove the spacer tool.
- Lubricate and fit No.4 cap.
- Fit and tighten No.4 cap securing bolts.
- Fit and tighten No.4 cap cylinder head bolt.
- Repeat the procedure for Nos 2, 3, 5 and 6 caps, left-hand camshaft.
CAUTION: The cylinder head bolts MUST be renewed during assembly and torque tightened as described under Engine, Service and Repair, Service Procedures, SPS Joint Control System.
- Set the left-hand camshaft to TDC.
- Repeat the procedure for the right-hand camshaft.
- Fit and align the camshaft sprockets to the chain and the camshafts.
- Move all the slack in the chain to the tensioner side.
- Fit upper chain tensioner tool 18G 1436/A (2 Fig. 1). Fit and tighten the tool securing bolts (1 Fig. 1).
- Tension the cam chain.
- Remove the camshaft coupling (12 Fig. 2) from the sprocket (11 Fig. 2) and align the securing bolt holes. Fit the bolts (2 Fig. 2) and tab washers (1 Fig. 2), tighten the securing bolts and lock over the tabs.
- Repeat the procedure for the other sprocket.
- Slacken off the chain tensioner tool securing bolts (1 Fig. 1).
- Remove the tensioner tool.
- Clean the tensioner assembly and gasket faces.
- Fit a new housing gasket (10 Fig. 2). Fit and lubricate a new `O' ring (9 Fig. 2).
- Fit the tensioner assembly (8, 9 Fig. 2) to the cylinder head. Fit and tighten the tensioner assembly securing bolt (3 Fig. 2).
- Fit but do not tighten the valve clamp bolt.
- Clean the valve assembly and fit new `O' rings (13 Fig. 2). Lubricate the tensioner valve (5 Fig. 2). Using an Allen key, release the tensioner, by turning the Allen key anti-clockwise.
- Fit the tensioner valve (5 Fig. 2). Position the clamp (4 Fig. 2) over the valve.
- Tighten the clamp bolt (3 Fig. 2).
- Refit the camshaft cover.