Connecting Rod Bearing Clearance Measurement Procedure

Important:  Connecting rod bearings that have been run in an engine should NEVER be reused.

1. Before final assembly it is important to check the clearance of the new connecting rod bearings.
2. Place a length of fresh, room temperature plastic gauging material all the way across the connecting rod bearing journal.
3. Install the connecting rod end cap on its original connecting rod making sure the bearing lock tangs are aligned on the same side of the rod.
   Fig 1: Installing Connecting Rod End Cap

   Courtesy of GENERAL MOTORS CORP.
   CAUTION: Refer to in FASTENER NOTICE .

   Important:  Reuse the old connecting rod bolts ONLY for measuring the connecting rod bearing clearance.

4. Lubricate connecting rod bolts with engine oil and install in the connecting rod.

   Tighten 

   Tighten the connecting rod bolts to 30 N.m (22 ft lbs).

5. Loosen the connecting rod bolts until the torque reading is zero.
6. Re-tighten the connecting rod bolts.
   1. 6.1. First Pass

      Tighten 

      Tighten the connecting rod bolts to 25 N.m (18 ft lbs).

   2. 6.2. Final Pass

      Tighten 

      Tighten the connecting rod bolts an additional 110 degrees using the J 36660-A. 

   Fig 2: Identifying J 36660

   Courtesy of GENERAL MOTORS CORP.
7. Allow the assembly to sit for at least two minutes.
8. Remove the connecting rod cap bolts.
9. Remove the connecting rod cap.
   Fig 3: Removing Connecting Rod Cap

   Courtesy of GENERAL MOTORS CORP.
10. Determine the connecting rod bearing clearance by comparing the width of the flattened plastic gauging material at its widest point with the graduation on the gauging material container.
Fig 4: Determining Crankshaft Bearing Clearance
Courtesy of GENERAL MOTORS CORP.
11. Compare your measurements with the Engine Mechanical Specifications . If the new bearings do not provide the proper crankshaft to bearing clearance, re-measure the crankshaft journals for the correct specified size and check to make sure you have the correct new bearings. If the crankshaft journals are incorrectly sized, replace the crankshaft. No crankshaft machining is permitted and undersized bearings are not available.
12. Clean the plastic gauging material from the connecting rod bearing journals using a soft lint-free cloth.