What is the valve clearance gap?
The valve clearance gap is a crucial aspect of engine maintenance that often goes overlooked by car owners. This gap, which refers to the space between the engine's valve and its rocker arm, plays a significant role in ensuring optimal engine performance. In this article, we will explore what valve clearance is, why it matters, and how to maintain it effectively.
What is Valve Clearance?
Valve clearance, also known as valve lash, is the distance between the tip of the valve and the rocker arm when the valve is closed. This gap is essential for the proper functioning of the engine's valvetrain, which controls the opening and closing of the engine's intake and exhaust valves. If the clearance is too tight or too loose, it can lead to various engine problems.
Why is Valve Clearance Important?
Maintaining the correct valve clearance is vital for several reasons:
- Engine Performance: Proper clearance ensures that valves open and close at the right times, optimizing engine performance and efficiency.
- Preventing Damage: Incorrect clearance can cause excessive wear on the valve and rocker arm, potentially leading to costly repairs.
- Fuel Efficiency: A well-adjusted valve clearance can improve fuel efficiency by ensuring that the engine operates smoothly.
- Emissions Control: Proper valve operation helps in maintaining optimal combustion, which can reduce harmful emissions.
In summary, valve clearance is crucial for maintaining engine health and performance, making it an essential aspect of regular vehicle maintenance.
How to Check and Adjust Valve Clearance
Checking and adjusting valve clearance is a task that can be performed by a skilled mechanic or a knowledgeable car owner. Here are the general steps involved:
- Gather Tools: You will need a feeler gauge, a wrench set, and possibly a screwdriver.
- Access the Valvetrain: Remove any necessary components to access the engine's valve cover.
- Measure Clearance: Use the feeler gauge to measure the gap between the valve and rocker arm. Refer to your vehicle's service manual for the correct specifications.
- Adjust as Necessary: If the clearance is not within the specified range, adjust it using the appropriate tools.
- Reassemble: Once adjustments are made, reassemble any components you removed and ensure everything is secure.
Regularly checking and adjusting valve clearance can prevent engine issues and prolong the life of your vehicle.
Conclusion
Understanding and maintaining the valve clearance gap is essential for any car owner who wants to ensure their vehicle runs smoothly and efficiently. By keeping an eye on this critical aspect of engine maintenance, you can avoid potential problems and enjoy a more reliable driving experience. If you're unsure about checking or adjusting valve clearance, don't hesitate to consult a professional mechanic for assistance.
Frequently Asked Questions
What happens if valve lash is too loose?
If the valve lash is excessive then valve lift is lost and in turn, intake port flow drops along with horsepower and torque.
What is the minimum valve clearance?
What is the minimum recommended clearance?
| Intake | Exhaust |
|---|---|
| 0.080 in. | 0.100 in. |
What will too little valve clearance do to the valve?
Too little clearance causes the valves not to fully close when the engine is up to operating temperature, and can cause burned valve tulips and seats.
What is acceptable valve guide wear?
However, if a purist had the equipment he would measure the i.d. of the guide (all the way through) and the o.d. of the worn part of the valve stem and compare them with the new spec'ns. One manual states total wear of zero to 4 thou wear of the guide is acceptable.
What is the rule of 13 valve clearance?
The “Rule of 13” applies to most 6 cylinder engines, subtract the open valve from 13 to see which one to adjust. To adjust slip the correct feeler gauge blade under the rocker and the top of the valve stem.
What happens if the valve clearance is too big?
Too much clearance causes the intake and exhaust valves to open late, impacting performance a bit. It also causes the valves to slam onto their seats, causing unnecessary wear.
How to calculate valve lash?
To determine the valve lash, subtract the squish from the desired valve opening lift. The cam in the graph is for a flathead, using squish of 0.002" the valve lash should be 0.0127" or 0.013". The exhaust could be set a couple thousandths larger to allow for thermal expansion.
What is the correct valve clearance?
Opinions may vary between piston and valve manufacturers, but a popular consensus is a minimum clearance of . 080-inch for the intake and . 100-inch for the exhaust. The exhaust valve expands more due to heat from combustion, and therefore needs additional clearance.
What is acceptable valve guide clearance?
A general rule of thumb is that intake guides need guide-to-stem clearance of . 001″ to . 003″ and exhaust guides need from . 002″ to . 004″ clearance.
What is a proper valve lash?
A critical factor for any engine is the proper clearances between parts. Valve lash is the available clearance (or gap) between the rocker arm and the tip of the valve stem when the lifter for that valve is sitting on the base circle of the cam lobe (when the valve is intended to be fully closed).
