LS 706 Head Specs [Features & Comparison with Other Cylinder Heads]

706 heads, also known as “706 cylinder heads,” are a specific type of cylinder heads commonly used in engines produced by General Motors (GM), specifically in their LS series. These cylinder heads are quite popular among engine enthusiasts due to their compatibility and desirable features.

The name “706” comes from the casting number associated with these heads. Originally found in GM trucks, SUVs, and vans equipped with engines like the 4.8L, 5.3L, and 6.0L, the 706 heads have gained a reputation for their versatility and performance potential.

Here are some of its key features and specs:

Material Composition

When it comes to 706 cylinder heads, you have two popular options: robust cast iron or lightweight aluminum alloy. Cast iron heads excel in handling high-stress situations, offering exceptional durability and heat dissipation.

On the other hand, aluminum heads provide a weight reduction advantage, leading to enhanced overall engine performance and improved fuel efficiency.

Port Design

The design of the intake and exhaust ports in 706 cylinder heads is nothing short of meticulous. These well-engineered ports optimize airflow, ensuring your engine breathes effortlessly.

By maximizing the engine’s ability to draw in air, these optimized port designs contribute to increased power output and torque. The shape, size, and contour of the ports are crafted with precision to promote efficient flow of the air/fuel mixture, resulting in better combustion efficiency.

Combustion Chamber Design

The combustion chambers within 706 cylinder heads are carefully crafted for peak performance. By incorporating an optimal combustion chamber design, these cylinder heads ensure efficient fuel burning, reducing emissions, and delivering power with finesse.

The shape and volume of the combustion chambers directly influence the engine’s compression ratio, which has a significant impact on overall performance.

Valve Configuration

A standard valve configuration of two intake valves and two exhaust valves per cylinder is the norm for 706 cylinder heads. The size and shape of these valves play a pivotal role in determining the engine’s airflow, horsepower, and torque characteristics.

With their carefully engineered design, these valves ensure smooth intake and exhaust flow, optimizing engine breathing and overall performance.

Valve Springs

To achieve precise valve control and operation, 706 cylinder heads rely on thoughtfully selected valve springs. These springs are designed to provide the necessary tension, ensuring optimal valve timing and closure.

By preventing valve float at high engine speeds, these well-calibrated valve springs safeguard the integrity of the valvetrain and contribute to optimal engine performance.

Valve Seats

The valve seats in 706 cylinder heads are meticulously crafted to provide a resilient and precise sealing surface for the valves.

High-quality valve seats contribute to maintaining optimal compression levels and preventing leakage during combustion. With their precise machining, these valve seats ensure a snug fit and a reliable seal.

Bolt Patterns

The bolt patterns of 706 cylinder heads are purposefully designed to guarantee proper alignment and secure fitment onto the engine block. Thanks to these accurate bolt patterns, installing and maintaining the cylinder heads becomes a hassle-free process.


It’s crucial to note that 706 cylinder heads are engineered to fit specific engine models such as the Chevrolet small-block engines that include 305, 350, and 400 cubic inch (CI) engines, GM V8 engines that include engines like the LS1, LS2, LS3, LS6, and LS7.

This ensures seamless compatibility with various vehicles, allowing for a proper fit and optimal functionality. Prior to installation, confirming the compatibility of 706 cylinder heads with the intended engine is essential.

Aftermarket Support

Due to their popularity, 706 cylinder heads enjoy a vibrant aftermarket support system. Performance enthusiasts can explore a range of aftermarket options, including upgraded components like valves, springs, and porting, for even greater performance gains.


In terms of price, 706-cylinder heads are often seen as a cost-effective option for engine upgrades and replacements. Prices may vary depending on factors such as the chosen material, brand, and any additional features or modifications.

Performance Potential

It’s no secret that 706-cylinder heads have gained a reputation for boosting horsepower and torque. Thanks to their improved airflow characteristics, these heads are highly sought-after by engine enthusiasts aiming to take their vehicle’s performance to the next level.

Benefits and Advantages of 706 Heads

The 706 heads offer a range of practical benefits and advantages that make them a popular choice among engine enthusiasts. Some of these benefits include:

  • Compatibility: One of the key advantages of 706 heads is their compatibility with a wide range of LS engines. Whether you’re working with a Gen III or Gen IV LS engine, these heads seamlessly fit into your setup. This versatility is a major plus for engine swaps or upgrades without the hassle of extensive modifications.
  • Cost-Effectiveness: if you’re budget-conscious, you’ll appreciate the affordability of 706 heads. Compared to some pricier aftermarket cylinder heads, these heads offer a cost-effective solution for enhancing LS engine performance. You can achieve noticeable gains without emptying your wallet, making it a practical choice for many.
  • Flow Characteristics: The 706 heads are known for their impressive flow characteristics, particularly in the lower to mid-range RPMs. This means you’ll experience improved torque and drivability, which translates to better acceleration and responsiveness during everyday driving or mild performance enhancements.
  • Aftermarket Support: Thanks to their popularity, the aftermarket support for 706 heads is abundant. Whether you’re seeking upgraded components, performance enhancements, or expert advice, you’ll find a wide range of options tailored specifically to these heads. The thriving community and resources make it easier to fine-tune your engine to meet your performance goals.
  • Upgrade Potential: While the 706 heads offer solid performance as they come, you can take things a step further through modifications. Engine builders can explore options like installing larger valves, fine-tuning the ports, or upgrading valve springs. These enhancements unlock additional power and performance, allowing you to push the boundaries even further.
  • Availability: Finding the right components for your engine project is crucial, and the good news is that 706 heads are widely available. You can source them from various suppliers, both original and aftermarket. This availability saves you time and effort in locating the necessary parts, ensuring a smoother and more convenient engine build.
  • Community Knowledge and Support: With the popularity of 706 heads, there’s a vibrant community of engine enthusiasts who have already explored their potential. Online forums, resources, and experienced individuals offer a wealth of knowledge and support. Whether you need advice on installation, troubleshooting, or optimizing performance, the community is there to help, ensuring a smoother journey.
  • Versatility: While the 706 heads were originally used in GM trucks, SUVs, and vans, their versatility extends beyond those applications. These heads can find a home in various projects, from street rods and muscle cars to custom builds. Their adaptable nature means you can leverage their performance benefits across different vehicle types and applications.

Comparison with Other Cylinder Heads

Cylinder HeadMaterial CompositionPort DesignCombustion Chamber DesignValve ConfigurationCompatibilityPerformance Potential
706 HeadsCast Iron or AluminumCathedralVaries2 valves per cylinderSmall-Block and LS EnginesGood potential with mild modifications
823 HeadsAluminumCathedral or D-ShapedVaries2 valves per cylinderLS-Based EnginesImproved potential with better airflow and performance parts
862 HeadsCast Iron or AluminumCathedralVaries2 valves per cylinderSmall-Block and LS EnginesModerate potential with mild modifications
243 HeadsAluminumCathedralLS1/LS6 Style2 valves per cylinderLS1, LS6, LS2, LS3, L92 EnginesGood potential with CNC porting and performance modifications
317 HeadsCast Iron or AluminumCathedralVaries2 valves per cylinderLQ4, LQ9, L76, L92, L99 EnginesModerate potential with mild modifications


In a nutshell, the 706 heads have become a go-to choice for LS engine enthusiasts looking to step up their game. Whether you’re a seasoned pro or a passionate DIYer, these heads offer a winning combination of compatibility, performance, and affordability.

With their wide compatibility, the 706 heads can seamlessly integrate into various LS engine setups, including popular GM trucks, SUVs, and vans. They provide a solid foundation for engine swaps and upgrades without the headache of complicated modifications.

What sets the 706 heads apart is their exceptional flow characteristics. This means improved torque and drivability, giving your vehicle that extra oomph you’ve been craving. Plus, the extensive aftermarket support means you can easily find the components and upgrades tailored specifically for the 706 heads, allowing you to fine-tune your engine to perfection.

The best part? The 706 heads won’t break the bank. They offer an affordable solution for enhancing your LS engine’s performance without draining your wallet. This makes them a practical choice if you want to experience the thrill of improved power without compromising on quality.