How To Measure Bearing Clearances On Your Engine - Step By Step | Real Street Performance

Summary

In this detailed video, Jay from Real Street Performance walks viewers through the critical process of measuring main and rod bearing clearance on a Honda B-series engine. He explains the tools required, key measurements, and the importance of maintaining proper oil clearance for engine performance and longevity. Jay covers topics such as measuring the main tunnel, checking crankshaft condition, and selecting the right bearings. He emphasizes the role of oil as both a lubricant and coolant, and offers insights on adjusting bearing clearance to ensure optimal oil flow, thus preventing premature engine failure.

Takeaways

• 😀 Proper bearing clearance is essential for engine success, ensuring sufficient oil flow and preventing metal-on-metal contact.
• 😀 Vertical oil clearance is the critical gap between the bearing and crankshaft, with larger clearance near the parting line of the block for oil reservoirs.
• 😀 Always use the right tools: inside micrometer, outside micrometer, and torque wrench, along with a service manual for proper specifications.
• 😀 When measuring the main housing bore, be sure to install main caps in their original positions, and torque them smoothly to avoid damaging threads or bearings.
• 😀 Bearing crush is crucial for proper seating of bearings; too little crush can lead to bearing failure and too much crush can cause deformation.
• 😀 When measuring crankshaft journals, avoid nicking the surface with the micrometer to ensure accurate readings and a good fit with the bearings.
• 😀 Use H (standard) and HX (extra clearance) bearings to fine-tune oil clearance in small increments, typically in half-thousandths.
• 😀 If working with a damaged or spun crankshaft, consider replacing it, especially if the crank has significant taper or ovality in the journals.
• 😀 Always measure thrust clearance (crankshaft endplay) to ensure it is within the specified range (usually around 0.004–0.005 inches).
• 😀 For rod bearings, label the caps to avoid mixing them up, and check the housing bore diameter before disassembling the rods for measurement.
• 😀 Using a mix of H and HX bearings allows for precise adjustments to achieve around 2 thousandths of clearance, a safe and common value for most performance builds.

Q & A

Why is it important to measure main and rod bearing clearance during an engine build?

Measuring bearing clearance is critical for ensuring proper oil flow and lubrication, which prevents metal-to-metal contact between engine parts. This helps avoid premature wear, overheating, and potential engine failure.

What tools are required for measuring bearing clearance?

You'll need an inside micrometer, outside micrometer, and a torque wrench. These tools allow for precise measurements of the bearing and crankshaft sizes to ensure the correct oil clearance.

How does bearing eccentricity affect oil clearance measurements?

Bearing eccentricity means that the clearance near the parting line of the engine block is larger than the vertical clearance. This larger clearance helps to act as a reservoir for oil to ensure better lubrication and cooling.

Why is vertical oil clearance considered the smallest clearance in an engine?

Vertical oil clearance refers to the space between the crankshaft and bearing at the tightest point. It is critical for maintaining oil flow to keep the engine parts lubricated and cool, preventing damage from friction.

How should the main caps be installed when measuring the bearing clearance?

The main caps must be installed in the same position and direction from which they were removed. This ensures the proper alignment of the bearings and avoids introducing any distortions that could affect clearance measurements.

What do you do if the crankshaft shows signs of taper or egg shape after being machined?

If the crankshaft has significant taper or egg shape, it may not be suitable for use. You should either replace the crankshaft or have it re-machined to ensure proper bearing clearance and oil flow.

What is the difference between H and HX bearing sets, and when should each be used?

H bearings are for standard clearance, while HX bearings provide extra clearance. HX bearings are useful when you need slightly more oil flow or are compensating for thermal expansion, especially in the main caps.

Why is it important to install bearings correctly in the engine block?

Installing bearings correctly ensures that the oil can flow properly through the bearing body, which helps keep the crankshaft lubricated. Incorrect installation can lead to poor oil flow and potential engine failure.

How do you measure the thrust clearance of the crankshaft?

To measure thrust clearance, use a magnetic base dial indicator attached to the main cap to check the front-to-back movement of the crankshaft. This clearance ensures the crankshaft has the proper endplay to operate smoothly.

What should you do if your bearing clearance measurements don’t seem right?

If your measurements are off, stop and troubleshoot the issue. Double-check the tool calibration, ensure the parts are clean, and verify the installation process. It's important not to make assumptions without understanding the root cause.