SR20 Dual Guide Shim Conversion

Eliminate the SR20’s most notorious weakness, throwing a rocker arm. Our Dual Guide Shim Conversion is the ultimate reliability upgrade for any SR20DET cylinder head seeing high RPMs or aggressive driving.

The factory SR20 valvetrain typically uses a guide shim on one valve and a flat shim on the other. Under high load or limiter bashing, this design allows the rocker arm to slide laterally and eject itself—"throwing a rocker"—often causing catastrophic damage to the cam and valves.

The Solution:

We precision machine the tip of each valve stem to get each pair to exact tolerances. This machining allows us to install OEM Nissan guide shims on both valves under a single rocker arm, rather than just one. This reduces the need for machining guide shims and having multiple different sizes on hand for test fitting.

Benefits:

• Rocker Arm Retention: By cupping the rocker arm on both sides with guide shims, lateral movement is virtually eliminated, preventing the rocker from sliding off the valves.

• Factory Geometry: All machining is calculated to maintain the rocker angle strictly within Nissan factory specifications, ensuring proper contact patches and valvetrain geometry.

• High-RPM Reliability: Significantly reduces the chance of valvetrain failure during drifting, track abuse, or limiter usage.