CHEVROLET PERFORMANCE LS3 ALUMINIUM CYLINDER HEAD ASSEMBLY – P/N 12629063

Great cylinder-head airflow has been a cornerstone of the LS engine family's extraordinary performance legacy—and the Chevrolet Performance LS3 Aluminium Cylinder Head Assembly (P/N 12629063) puts that advantage directly in your hands. Fully assembled and ready to install, this production-style aluminium head suits any LS family engine running a 4.000" bore or larger—including Holden Commodore Gen III and Gen IV LS applications—delivering as-cast L92-style port geometry, premium valve components, and factory-validated performance straight out of the box.

BOLT-ON PERFORMANCE. NO COMPROMISES.

Chevrolet Performance's extensive research and development program has produced a range of aluminium cylinder heads that many professional builders use as straight bolt-ons—no further machining required. The LS3 head sits at the heart of this lineup, offering exceptional out-of-box airflow through as-cast L92-style intake ports and D-shaped exhaust ports. Whether you're refreshing a tired Commodore top end, building a street-strip LS combination, or laying the foundation for a serious performance build, this is the head that gets the job done right the first time.

Manufactured from 319-T5 aluminium alloy with high-efficiency combustion chambers and symmetrical intake and exhaust ports, the LS3 head is engineered for maximum airflow without compromise. The 15° valve angle, angled spark plug positioning, and bolt-down rocker arm design are all hallmarks of the LS platform's well-proven architecture—and this head delivers every one of them.

FULLY ASSEMBLED. TRACK-READY.

Unlike bare castings that demand additional sourcing and assembly time, the LS3 head (P/N 12629063) arrives complete with a full valvetrain component set—so you can focus on the build, not the parts chase. Every component is Chevrolet Performance spec, ensuring perfect fitment and consistent performance across the entire valve train.

KEY BENEFITS

Achieve proven LS3 airflow gains with zero machining required, save time with a fully assembled valvetrain, fit a wide range of LS and Commodore applications with a single part number, and build with total confidence on a factory-validated, OEM-engineered platform.

Key Features:

• Fits All LS Family Engines – 4.000" Bore or Larger – Broad compatibility including Holden Commodore Gen III and Gen IV LS applications
• As-Cast L92-Style Intake Ports – Factory-optimised airflow geometry, straight out of the box
• D-Shaped Exhaust Ports – Efficient exhaust scavenging for improved power output
• 2.165" Hollow Stem Intake Valves – Lightweight design for high-rpm capability
• 1.590" Solid Stem Exhaust Valves – Built for durability under sustained performance use
• 0.550" Maximum Valve Lift – Compatible with a wide range of performance camshaft profiles
• 319-T5 Aluminium Alloy Construction – Lightweight, thermally efficient, and built to last
• High-Efficiency As-Cast Combustion Chambers – Optimised for efficient combustion and compression
• 15° Valve Angle – Proven LS architecture for optimal port geometry and airflow
• Angled Spark Plug Design – 14mm, 5/8" hex, 3/4" reach taper-seat plugs
• Bolt-Down Rocker Arms & Centre-Bolt Valve Covers – Direct compatibility with standard LS valvetrain components
• Fully Assembled – Complete valvetrain components included; ready to install
• Gen III & Gen IV Small-Block Compatible Only – Fits LS-series architecture exclusively

Specifications: