Silver Seal B306 VSI Valve Spring Insert Shim Type B - 030 50-Pack

The Silver Seal B306 is a Type B, .030" thickness VSI® Valve Spring Insert (shim) — part of Silver Seal's original, patented valve spring insert system trusted by engine builders since 1959. These inserts are installed under valve springs to restore proper installed height and spring pressure lost during valve and seat reconditioning work.

Refacing valves and grinding or cutting valve seats removes metal, which directly reduces spring pressure. The B306 insert compensates for this material loss, restoring correct spring tension and ensuring consistent valvetrain performance. The Type B (.030") inserts are silver-colored and case hardened for long-term durability under high heat and load conditions.

Key Features:

• Type B — .030" thickness, silver-colored, case hardened steel construction
• Patented heat-slashing serrations equalize installed height and pressure across all valve springs
• Protects cylinder head spring pads from spring abrasion
• Will not compress under load, maintaining correct spring pressure
• Dimensions: 1.438" OD × 0.645" ID
• Part of Silver Seal's complete VSI® system — compatible with A306 (.060") and C306 (.015") for full-range correction

Silver Seal VSI® inserts are a staple in professional engine rebuild and machine shop environments. The B306 is ideal for restoring spring pressure on slightly worn or freshly reconditioned cylinder heads where only moderate correction is needed.