Valve Shim Gap Measurement/Replacement Procedure
Please look more closely at that little formula in the spreadsheet. It shows "1-2+3." The process for the valve gapping portion of the upper 60K isprovided below. This is an excerpt from my procedure.
Perform the following 12 steps for each of the 24 valves as they become accessible.
1. Measure the valve clearance with the feeler gauge and record the as-found gap values in the 1) Gap - As Found row of the worksheet. The valve gap measurement is the thickness of the feeler gauge that will fit into the gap without friction from the cam lobe and the shim. Even if the gap is at the nominal gap value, it is prudent to remove the shim to inspect it for abnormal wear or scoring. Shims with obvious wear or scoring should be replaced. Always check the gap of the shims after they are reinstalled even if the new shim has the same indicated thickness.
2. Rotate the tappet bucket with your finger until the notch in the bucket is accessible.
3. Depress the tappet with the tappet compressor tool positioned immediately adjacent to the cam lobe.
4. Position the tappet holder tool on the edge of the tappet bucket to hold the bucket in the depressed position and remove the tappet depressor. It is helpful to have the tappet holder's handle positioned towards the outside edge of the head to allow clearance for the shim to be removed to the inside direction. It is also helpful to attach a lanyard or leash to the tappet holder in case it pops free of the tappet.
5. Use the shim pick in the notch to pry the shim free from the tappet bucket. There is usually suction provided by the oil film holding the shim in place.
6. Use the magnet on the shim pick to remove the lifted shim from the bucket.
7. Record the thickness of the removed shim in the 3) Old Shim row of the worksheet. Example: 2525 is a 2.525mm shim.
8. Perform the calculation shown in the 4) Reqd Shim [1-2+3] row of the worksheet and record the result in this same row.
9. Locate a shim that is closest to the value determined above. It is desirable to set the gap the nominal value or a little tighter so round up to the next thicker shim. If it is desired to set the gaps at the nominal value, round to the nearest shim size.
10. Put a few drops of engine oil on the face of the shim to be placed upward and install the shim. Both faces of the shims are useable, but shims with a dark spot in the center should have the spot cleaned off before using this face. New shims do not have this spot and may have either side facing upward. Deposits of oil and debris during operation of the engine create the dark spot.
11. Depress the tappet with the tappet compressor and remove the tappet holder. Use the tappet compressor to repeatedly pump the oil from under the shim to ensure it is seated.
12. Check the gap to ensure it has been set to the desired value. If not, replace the shim with another of the same indicated size (not all shims are exactly the thickness as marked), or the next thicker or thinner size as appropriate. If the gap is measured to be at the desired clearance, record the installed shim thickness in the 5) Shim Installed row of the worksheet and the final measured gap in the 6) Gap - As Left row.
