How to Adjust 350 Chevy Valves? Quick 4 Steps!

4 Easy Steps on How to Adjust 350 Chevy Valves!

In adjusting the valve lash on GM engines, both small and big block, the procedure should be clear and easy. Whether you’re a professional technician, an engine builder, a racer, or a home mechanic trying this for the first time, the key lies in understanding the correct techniques. The service manuals and camshafts instructions often seem confusing, with advice that varies from one source to another.

My approach, honed over years as a do-it-yourselfer, simplifies the task. It involves a step-by-step process, avoiding the issues often not covered in the general information. This entire article is dedicated to demystifying engine maintenance, particularly valve adjustment in V-type engines.

Remember, adjusting valves is more than just following procedures; it’s about grasping the nuances of your Chevy 350. For any specific questions, the instructions here should be your first source of information. 

Valve Adjustment Procedure Step By Step Guide

Valve Adjustment Procedure Step By Step Guide

When adjusting the valves of a 350 Chevy, whether the engine is hot or cold, precision is key. Major camshaft manufacturers often recommend setting the valves on a cold engine. This practice helps avoid erroneous adjustments especially in lifters that might be “pumped up”. 

For those working on a fresh engine that hasn’t yet been run, make sure every part is well lubricated before you begin. Not only does this make the job comfortable, but it also ensures the longevity and efficiency of your engine’s performance.

1. Removing Valve Covers and Spark Plugs

Removing Valve Covers and Spark Plugs

During the process of setting the valves on a 350 Chevy, the first step involves removing the valve covers and spark plugs. This makes the engine much easier to turn over. For clarity and to make the task less confusing, it’s advisable to loosen all the rocker arm adjustment nuts across all cylinders. 

This allows the internal lifter plungers to return to their home position. Taking these initial steps ensures that everything is correctly aligned, making the actual valve adjustment process smoother and more straightforward.

2. Turning the Engine

Turning the Engine

Start by using a long-handled ratchet or breaker bar on the crank bolt to turn the engine in a clockwise direction.

  • Adjusting #1 Cylinder

With the #1 cylinder, turn the engine until the exhaust pushrod just begins to move up. At this point, stop and adjust the intake valve of the same cylinder.

  • Fine-Tuning Valve Adjustment

After adjusting the #1 intake valve, continue to turn the engine, watching the intake pushrod. When it’s full open and begins to close, nearing almost closed, stop and adjust the exhaust rocker arm on the same cylinder. This procedure ensures the lifters are at the base circle of the cam, eliminating any additional pre-load.

  • Completing the Process

Finally, repeat this procedure for the remaining cylinders.

3. Finalizing the Valve Adjustment Process

The final step valve adjustment procedure on a 350 Chevy is crucial yet often overlooked. Once all adjustments are made, it’s essential to re-install the valve covers securely. This not only protects the internal components but also signifies the completion of your task. With the valve covers back in place, you can confidently know that your valve adjustment procedure is finished, ensuring your engine runs smoothly and efficiently.

4. Instructions & Precautions

While you may be adjusting 350 Chevy valves on a cold engine for comfortability, it’s good to warm up the engine and then shut off before starting the replacement process. 

  • Preload adjustment should be done slowly, allowing the lifter to adjust properly. This step is crucial to prevent interference between the intake valve head and the top of the piston, which could lead to internal damage or bent push rods. 
  • Always refer to the Manufacturer’s Recommended Specifications to thoroughly work on and ensure valves are adjusted properly. 
  • If you encounter noisy lifters, you can replace them too as part of the maintenance process.

How to know if Valves Need Adjustment on A 350 Chevy?

Identifying when the valves on a 350 Chevy need adjustment is crucial for engine maintenance. Recognizing the symptoms can prevent further issues and ensure optimal performance.

  • Rattling Sounds: Indicate loose valves.
  • Overheating Engine: Often due to the tightness of valves.
  • Increased Fuel Consumption: Sign of combustion rate issues.
  • Pre-Ignition: A clear sign of adjustment needs.
  • Poor Engine Performance: Indicates potential valve issues.
  • Sudden Engine Light Activation: Could signal valve problems.
  • Engine Jerks: When the car is moving, a sign of valve maladjustment.

Frequently Asked Questions (FAQs):

What are symptoms of valves out of adjustment?

Incorrect valve adjustment can lead to insufficient heat transfer from the valve to its seat, potentially causing valve warp or seat pitting​​.

How do you adjust SBC valves?

For SBC valves, after finding the top dead center on the balancer, adjust both #1 valves, then rotate the engine 45 degrees and adjust #8 valves, continuing in this manner through the firing order, using the “spin the push rod” method​​​​.

What order do you adjust valves?

Valves should be adjusted by rotating the engine until the piston is at the top dead center of the compression stroke, then adjusting the clearance between the valve stem and rocker arm​​​​.

How could you know if the valve clearance needs to be adjusted?

An increase in exhaust smoke and the engine not operating at full power are signs that valves need adjusting. Understanding valve clearance, the gap between the rocker arm and the valve, is crucial​

What will too little valve clearance do to the valve?

Too little valve clearance can lead to valves not seating properly, causing insufficient cooling and potential valve damage.

What happens if valves are too tight?

If valves are too tight, they may not close completely, risking overheating, decreased engine performance, and potential damage to the valve and seat.

Is it better to have tight or loose valves?

Neither extreme is ideal; too tight valves risk engine damage, while too loose valves can cause performance issues.

Are loose valves better than tight?

Loose valves are generally less harmful than tight valves but can still lead to engine inefficiency and noise.

Will valves out of adjustment cause backfire?

Incorrect valve adjustment can lead to backfiring, among other engine performance issues.

Conclusion

Adjusting the valves on a 350 Chevy engine is a task that blends precision with a bit of personal finesse. From ensuring the right valve clearance to understanding the nuances of each step, the process is detailed but highly rewarding. In my experience, paying close attention to each adjustment, especially being mindful of the valve clearance, has always been key to maintaining engine performance and longevity. 

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