Wiseco W4954 Groove Lock Spacer Oil Rail Support

The Wiseco W4954 Groove Lock Spacer is a precision oil ring support component designed for use with Wiseco forged pistons where the wrist pin bore intersects the oil ring groove. Also known as an Oil Rail Support (OSR), this part prevents the oil ring rails from protruding into the wrist pin opening during engine operation — a critical requirement in short compression height applications resulting from large strokes or long rod lengths.

Key Features:

• Spring steel construction for durability and consistent tension throughout the operating range
• Dimple-down orientation locks the spacer in place and prevents rotation — dimple must face downward over the wrist pin hole, positioning the end gap 90 degrees from the wrist pin
• Installed against the bottom sill of the oil ring groove prior to oil ring assembly
• Compatible only with pistons that have a groove machined 0.030 inches wider than the standard oil ring
• Ensures optimal oil control and consistent piston performance across the full RPM range
• Sold individually — one (1) Groove Lock Spacer per package

Installation Note: This spacer must be installed before the oil ring assembly. Position with the dimple facing downward and oriented over the wrist pin hole. This ensures the end gap sits 90 degrees away from the wrist pin for proper sealing and support.

Wiseco is a world leader in performance forged pistons, engineered and machined in the USA at their Mentor, Ohio facility. The W4954 Groove Lock Spacer is part of their comprehensive lineup of piston accessories built to complement their performance piston sets.