Installing Cam Bearings in an SBC: A Comprehensive Guide

Installing cam bearings in a small block Chevrolet (SBC) engine is a crucial step in rebuilding or modifying the engine. Properly installed cam bearings ensure proper crankshaft support and oil flow, which are essential for engine longevity and performance. This article provides a step-by-step guide to installing cam bearings in an SBC, along with tips, tricks, and advanced features to consider.

Understanding Cam Bearings

Cam bearings are thin, cylindrical sleeves that fit into the engine block and support the camshaft. They provide a smooth, low-friction surface for the camshaft to rotate on, and they also serve as oil passages to lubricate the camshaft and adjacent components. Cam bearings are typically made of bronze or steel and are available in various sizes and clearances to accommodate different engine applications.

Tools and Materials

To install cam bearings in an SBC, you will need the following tools and materials:

• Cam bearing installation tool
• Cam bearings (size and clearance appropriate for your application)
• Engine block
• Plastigage
• Micrometer
• Dial indicator
• Hammer
• Drill
• Tap set
• Machinist's blue

Step-by-Step Installation Instructions

1. Prepare the Engine Block:

• Clean the cam bearing bores in the engine block thoroughly. Remove any rust, debris, or old bearing material.
• Check the cam bearing bores for any damage or wear. If necessary, replace or repair the block.

2. Measure the Cam Bearings:

• Use a micrometer to measure the outer diameter of the cam bearings.
• Measure the inner diameter of the cam bearing bores in the engine block.
• Calculate the clearance between the cam bearings and the bores by subtracting the inner diameter from the outer diameter. The ideal clearance is typically between 0.001" and 0.003".

3. Apply Plastigage:

• Apply a thin layer of Plastigage to the cam bearing surface that will contact the crankshaft.
• Insert the cam bearing into the bore and carefully rotate the cam bearing using the installation tool.
• Remove the cam bearing and measure the width of the flattened Plastigage strip. This will give you the actual clearance between the cam bearing and the crankshaft.

4. Adjust the Bearing Clearance:

• If the clearance is too tight, you can remove material from the cam bearing bore using a drill and tap set.
• If the clearance is too loose, you can replace the cam bearing with a smaller one or use a bearing shim to reduce the clearance.

5. Install the Cam Bearings:

• Apply a thin layer of engine assembly lubricant to the cam bearing bores and the cam bearings.
• Carefully insert the cam bearings into the bores and tap them into place using a hammer and drift punch.
• Use a dial indicator to check the runout of the cam bearings. The runout should be less than 0.001".

Tips and Tricks

• Use a cam bearing installation tool to ensure proper alignment and prevent damage to the cam bearings during installation.
• Check the cam bearings for any burrs or imperfections before installing them.
• Use a small amount of engine assembly lubricant to the cam bearing bores and the cam bearings to reduce friction during installation.
• Double-check the clearance between the cam bearings and the crankshaft using Plastigage before running the engine.

Why It Matters

Properly installed cam bearings are crucial for the following reasons:

• Engine Longevity: Cam bearings provide support to the camshaft, reducing wear and extending the life of the engine.
• Oil Flow: Cam bearings act as oil passages, ensuring that oil is supplied to the camshaft and other critical components.
• Performance: Cam bearings with the correct clearance minimize friction and improve engine performance.

Benefits of Proper Installation

• Reduced wear and tear: Properly installed cam bearings reduce friction between the camshaft and crankshaft, extending the life of both components.
• Improved engine performance: With less friction, the camshaft can rotate more freely, resulting in improved engine performance.
• Reliability: Properly installed cam bearings help to maintain optimal oil flow and prevent premature engine failure.

Advanced Features

• Grooved Cam Bearings: Some cam bearings feature grooves or slots to improve oil flow and reduce friction.
• Self-Aligning Cam Bearings: These cam bearings have a spherical inner surface that allows them to automatically align with the crankshaft, reducing the risk of misalignment.
• High-Performance Cam Bearings: Cam bearings designed for high-performance engines are typically made from stronger materials and have tighter tolerances to handle increased loads and RPM.

Three Humorous Stories on Cam Bearing Installation

1. The Rookie's Mistake: A rookie mechanic installed cam bearings without checking the clearance. When the engine was started, the bearings seized and destroyed the camshaft. Lesson: Always check the clearance before running the engine.

2. The Overzealous Mechanic: A mechanic tightened the cam bearings too much, thinking it would make the engine more durable. However, the tight clearance caused excessive friction and premature wear. Lesson: Follow the recommended torque specifications.

3. The Oil-Starved Engine: A mechanic forgot to lubricate the cam bearings before installation. The engine ran for a short time but seized up due to lack of lubrication. Lesson: Never skip the lubrication step.

   

Conclusion

Installing cam bearings in an SBC is a crucial step in engine rebuilding or modification. By following the steps outlined in this guide and considering the tips, tricks, and advanced features discussed, you can ensure proper installation and reap the benefits of reduced wear, improved performance, and increased reliability for your SBC engine.