REMOVAL & INSTALLATION
See Figures 1, 2, 3 and 4
Disconnect the negative battery cable.
Remove the timing chain front cover.
During timing chain and sprocket removal, position the crankshaft 90 degrees past Top Dead Center (TDC), to make sure the pistons will not contact the valves upon assembly.
Carefully rotate the crankshaft clockwise so the timing mark on the crankshaft sprocket and keyway align with the main bearing cap split line (90 degrees past TDC).
Remove bolts, then remove the timing guides and tensioner.
Remove the camshaft sprocket bolt, using a 7/8 in. (21mm) wrench to hold the camshaft. Then remove the timing chain and camshaft sprocket. Remove the crankshaft sprocket, if necessary.
Inspect the chain for wear and damage. Check the inside diameter of the chain, it should be no more than 16.77 in. (426mm). Inspect the chain guides for wear or cracks and the timing sprockets for teeth or key wear. Replace components as necessary.
Verify that the crankshaft is positioned 90 degrees clockwise past TDC from the keyway (keyway at 3 o'clock).
Bring the camshaft up to No. 1 TDC by loosely installing the sprocket and rotating the sprocket until the timing pin can be inserted. The camshaft contains wrench flats to assist in turning the shaft. The dowel pin should be at 12 o'clock when the camshaft is at TDC and a timing pin (3/16 in. drill bit) should then install at about the 8 o'clock position.
If removed, install the crankshaft sprocket, then rotate the crankshaft counterclockwise 90 degrees up to No. 1 TDC (keyway at 12 o'clock).
Position the chain under the crankshaft sprocket and over the camshaft sprocket. If necessary remove the camshaft sprocket, then slide the camshaft sprocket into position with the chain already engaged. The timing chain should be positioned so that one silver link plate aligns with the reference mark on the camshaft sprocket and the other aligns with the downward tooth (at the 6 o'clock position) on the crankshaft sprocket. The letters FRT on the camshaft sprocket must face forward, away from the cylinder head and excess chain slack should be located on the tensioner side of the block.
Temporarily install the timing pin to verify proper alignment of the camshaft and sprocket, then install and tighten the sprocket bolt to 75 ft. lbs. (102 Nm). Again, use a wrench on the camshaft flats to hold the shaft in position while tightening the bolt. Do not allow the camshaft retaining bolt to torque against the timing pin or cylinder head damage will result.
Install the chain guides with the words FRONT facing out. Install the fixed guide first and verify the chain is snug against the guide, then install the pivot guide. Tighten the bolts to 19 ft. lbs. (26 Nm) and verify that the pivot guide moves freely.
Retract the tensioner plunger and pin the ratchet lever using a 1/8 in. No. 31 drill bit inserted in the alignment hole at the bottom front of the component. Install the tensioner and tighten the bolts to 14 ft. lbs. (19 Nm), then remove the drill bit.
Make one final check to verify all components are properly timed, then remove all timing pins.
Install the timing chain front cover.
Connect the negative battery cable, start the engine and check for leaks.
Fig. 1: At 90 degrees past TDC, the crankshaft sprocket timing mark and keyway will align with the main bearing cap split line
Fig. 2: Exploded view of the timing chain and sprocket assembly-SOHC engine
Fig. 3: Insert the timing pin to ensure that the camshaft is at No. 1 TDC-SOHC engine
Fig. 4: When the camshaft is at TDC, rotate the crankshaft counterclockwise 90 degrees to achieve TDC