Hello Natasha,
The valve clearance on this engine is not directly adjustable.
The valve tappets determine the clearance, if not within specification they will need to be replaced
To check
Remove the valve/rocker cover
Rotate the crankshaft pulley in the direction of engine rotation, aligning the pulley groove with the 0 point on the cover, in order to set engine to TDC. See image 1
Measure the valve clearance at positions (1), (2), (6) and (8). See image 2
Rotate the crankshaft pulley 360 degrees in the direction of engine rotation.
Measure the valve clearance at positions (3), (4), (5) and (7). See image 2
If the measured values are not within specifications, replace the valve tappets. Use a micrometer to measure the tappet thickness. See image 3 and 5
Specifications
Inlet Side: 0.075-0.125 mm
Exhaust Side: 0.245-0.295 mm
Determine the tappet size. Refer to determining replacement tappet size.
. Remove the old tappet.
Measure the old tappet.
Perform the following calculation to determine the replacement tappet size:
Specifications
Inlet: value of removed tappet + measured clearance - 0.1 mm = new tappet size
Exhaust: value of removed tappet + measured clearance - 0.27 mm = new tappet size
Example:
- Old tappet = 3.20 mm, clearance was 0.30 mm, Intake clearance value is 0.1 mm
- 3.20 mm + 0.30 mm--0.1 mm = 3.40 mm
- 3.40 mm = 96449615 (part number)
In image 4 is a list of available tappets from GM, part numbers and clearances
Hope this helps.
Cheers, Boris
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Friday, May 19th, 2023 AT 4:03 AM