Brass Plug - Block Core Hole

The Brass Plug - Block Core Hole (MPN 9427693) from Chevrolet Performance is a freeze plug engineered to seal the coolant passages in an engine block where core holes are drilled during casting. For mechanics and engine builders working on small-block and big-block Chevrolet engines, this brass core hole plug is an essential component that prevents coolant leakage from the often-overlooked core drain cavities. Whether you're rebuilding a classic muscle car engine, restoring a vintage truck, or performing a complete machine shop overhaul, a properly seated core hole plug ensures you won't lose coolant during initial startup or ongoing operation.

Constructed from brass with a 5/8-inch diameter design, this freeze plug combines corrosion resistance with reliable sealing characteristics under typical engine operating pressures. Brass is the preferred material for core hole plugs because it resists rust and pitting that often occurs in cast iron blocks, ensuring a longer service life than steel alternatives. The natural finish and compact dimensions (4 x 0.45 x 4.4 inches) allow for straightforward installation in tight engine block passages without requiring special tools—a simple press fit with careful alignment is all that's needed for a watertight seal that will hold through thousands of engine cycles.

This universal-fit core hole plug is ideal for DIY builders, professional machine shops, and restoration specialists replacing original equipment or upgrading to a more durable solution. Installation is straightforward: clean the block passage thoroughly, ensure the hole is properly sized, and press the brass plug in place until it sits flush—no sealant is typically required if the plug diameter is correct. Chevrolet Performance's reputation for OEM-quality components makes this freeze plug a reliable choice for anyone serious about preventing coolant leaks and maintaining proper engine cooling system integrity during rebuild or modification work.