Rocker Arm Nuts & Poly Lock Nuts

What Are Poly Lock Nuts Commonly Used For?

Rocker arm nuts, also known as poly lock nuts or nut rockers, play a crucial role in the valvetrain assembly of many internal combustion engines, particularly in performance and racing applications. These nuts are commonly used for:

• Valvetrain Adjustment: Poly lock nuts are used to secure rocker arms to the rocker arm studs. They are often found in applications where precise valve lash adjustment is required. Valve lash refers to the clearance between the rocker arm and the valve stem. Proper adjustment ensures the valves open and close at the correct time, optimizing engine performance.
• High-Performance Engines: These nuts are especially crucial in high-performance and racing engines, where fine-tuning valve lash is essential to maximize power output and ensure reliable operation at high RPMs.
• Preventing Backing Out: Poly lock nuts have a nylon insert that helps prevent them from backing out due to engine vibrations, ensuring the rocker arms maintain the correct adjustment over time.

How Do You Tighten Poly Lock Nuts?

Properly tightening poly lock nuts is essential to achieve the correct valve lash and ensure your engine runs smoothly. Here's a general process for tightening poly lock nuts:

1. Rotate the Engine: Rotate the engine until the cylinder you're working on is at top dead center (TDC) on the compression stroke. This ensures the valves are closed for that cylinder.
2. Loosen the Nut: Loosen the poly lock nut, allowing some play in the rocker arm.
3. Adjust Valve Lash: Use a feeler gauge to measure the valve lash clearance. Adjust it to the manufacturer's specifications by turning the rocker arm stud or the poly lock nut itself. Tighten the nut while holding the stud in place until the correct valve lash is achieved.
4. Final Tightening: Once the valve lash is correctly set, use a wrench to tighten the poly lock nut securely against the rocker arm. The nylon insert in the nut will help keep it in place.

How Much Do Poly Lock Rocker Arm Nuts Cost?

The cost of poly lock rocker arm nuts can vary depending on factors such as the brand, material, and quantity. On average, you can expect to pay between $20 and $50 for a set of poly lock rocker arm nuts. The price may also vary based on whether you need them for a specific engine application or if you're purchasing them as part of a valvetrain kit.

Investing in quality poly lock nuts is important for reliable engine performance and valve adjustment, especially in high-performance and racing engines where precision matters.