| Subject: | Second Design Connecting Rod Bolt and Torque Specification |
| Models: | 1997-99 Chevrolet Corvette |
| 1999 Chevrolet and GMC C/K Models (Silverado and Sierra) |
| with 4.8 L, 5.3 L, 5.7 L, or 6.0 L V8 Engine
(VINs V, T, G, U -- RPOs LR4, LM7, LS1, LQ4) |
This bulletin is being issued to revise the Fastener Tightening Specifications
and the Piston, Connecting Rod, and Bearing Installation procedures in Section 6
Engine Mechanical of the Service Manual. A second design connecting rod bolt
will be introduced for the 1999 model year. Either design bolt, (when used
in pairs and properly tightened) may be used with 1997-99 connecting
rods. Add the second design bolt description and torque specifications to
the appropriate Service Manual information.
Identify the type of connecting rod bolt.
| • | The first design connecting rod bolt (1) can be identified by
a single dimple/mark on the head of the bolt and no retaining sleeve (3) on
the bolt shank. |
| • | The second design connecting rod bolt (2) can be identified by
two dimples/marks on the head of the bolt and a retaining sleeve (3) on the
bolt shank. |
Important: When replacing the connecting rod bolts, both bolts MUST be of the same
design for each connecting rod assembly. The use of different design connecting
rod bolts on the same connecting rod may lead to uneven clamploads and/or
connecting rod bearing bore distortion.
Install the bearing, cap, and bolts.
Tighten
| • | Tighten the first design bolts: |
| | First pass evenly to 20 N·m (15 lb ft). |
| | Final pass to 60 degrees using the J 36660. |
| • | Tighten the second design bolts: |
| | First pass evenly to 20 N·m (15 lb ft). |
| | Final pass to 75 degrees using the J 36660. |
