GMC 376445 Gm Cylinder Heads 5.7

( Manufacturer Part Number: 376445 ), ( Type: Cylinder Head ), ( Manufacturer Warranty: 1 Year ), ( Items Included: Bolts ), ( Vintage Part: No )

Review GMC 5.7 Gm Cylinder Heads fits 350

The **GMC Part Number 376445 5.7L GM 350 V8 Cylinder Heads** are a high-performance, precision-engineered component designed to deliver exceptional power, reliability, and durability for the iconic **LS1-based 5.7L (350 cubic inch) V8 engine** found in classic and modern GMC trucks, including models like the **Sierra, Yukon, and Denali**, as well as Chevrolet applications such as the **Corvette (C6), Camaro SS, and SS Trucks**. These cylinder heads are crafted from **high-strength cast iron**, ensuring robust structural integrity while maintaining optimal heat dissipation to prevent warping or premature failure under heavy loads. Each head features **four-valve-per-cylinder architecture**, incorporating **intake and exhaust valves** with **stainless steel stems** and **hardened valve seats** to resist wear, corrosion, and thermal expansion, even under extreme high-performance conditions. The **piston-to-valve clearance** is meticulously optimized to prevent contact during high-revving applications, making these heads ideal for both **street and strip** use, whether in stock configurations or when paired with **forced induction (turbocharged or supercharged)** setups. The **combustion chamber design** is finely tuned for **efficient fuel-air mixture distribution**, promoting better combustion efficiency and reduced knocking, while the **integrated valve springs and retainers** are engineered to handle high RPMs and aggressive camshaft profiles without losing tension. For enhanced performance, these heads often come with **ported and polished intake and exhaust passages**, improving airflow and scavenging, which translates to **noticeable gains in horsepower and torque** especially when paired with a **high-flow intake manifold, performance camshaft, and upgraded fuel system**. Additionally, the **threaded spark plug holes** and **precise valve guide alignment** ensure a seamless fit with aftermarket components, making these heads a versatile choice for both **restoration projects** and **high-performance builds**. Whether you're restoring a **1997 2007 LS1-era GMC truck** to factory specs or pushing a **modified 5.7L engine** to its limits, these **GMC 376445 cylinder heads** provide the foundation for a **reliable, high-revving, and torque-rich powerplant** that balances strength, efficiency, and performance. Built to meet **OEM specifications**, they are a direct replacement for factory heads, ensuring compatibility with stock or upgraded components while offering the durability needed for **daily driving, towing, or track use**.

### Pros and Cons of Buying GMC 376445 5.7L GM 350 Cylinder Heads

1. **Compatibility and Availability** These cylinder heads are designed for the GM LS-series engines, which are widely used in vehicles like the GMC Sierra, Chevrolet Silverado, and others. The 5.7L (350 cubic inch) version is a common and well-documented engine, making parts and support readily available.

2. **Performance Potential** The 350-series heads are capable of supporting significant power increases with proper modifications. They can handle forced induction (turbocharging or supercharging) and high-performance camshafts, making them a solid choice for enthusiasts looking to build a high-output engine.

3. **Durability and Reliability** The GM 350 heads are built to handle high RPMs and power levels, especially when paired with a strong engine block and supporting components. Many aftermarket upgrades (such as porting, polishing, or upgrading valves) can improve airflow and efficiency.

4. **Aftermarket Support** There is a vast array of aftermarket parts available for these heads, including upgraded valves, springs, retainers, and even full head replacements if needed. Companies like JE, Comp Cams, and Edelbrock offer performance-oriented components tailored for the 350 heads.

5. **Cost-Effective Upgrade** Compared to some other high-performance heads, the 350 heads are relatively affordable, especially when purchased used or from a reputable salvage yard. This makes them a cost-effective option for builders on a budget.

6. **Easy to Modify** The heads are relatively straightforward to work on, with common issues like valve seat replacement, porting, or valve job being manageable for experienced DIYers. Many performance shops also offer head porting services.

7. **Long-Term Investment** If maintained properly, these heads can last for decades, even in high-performance applications. Many LS-based engines built for street or strip use continue to run reliably with proper care.

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- **Valve Seat Wear or Failure** The stock valve seats can wear out, leading to poor sealing and potential overheating or detonation. Upgrading to aftermarket seats (e.g., Stellite or ceramic) is often recommended for high-performance builds.

- **Head Gasket Failures** If the head gasket is not replaced regularly or if the heads are not properly torqued, leaks or warping can occur. This is more critical in forced-induction applications.

- **Warping** Overheating or improper cooling can cause the heads to warp, leading to poor sealing and potential engine damage. Regular inspection and cooling system maintenance are essential.

- **Valvetrain Stress** The stock valvetrain may not be adequate for high RPM or high-power applications, leading to valve float or spring failure. Upgrading to stronger springs, retainers, and pushrods is often necessary.

- **Valve Jobs** The valves, guides, and seats should be serviced every 60,000 100,000 miles to prevent wear and ensure proper sealing.

- **Porting and Polishing** While not always necessary, porting and polishing the heads can significantly improve airflow and power, though this requires skill or professional help.

- **Cooling System Upgrades** Forced induction or high-power applications may require upgraded radiators, oil coolers, or intercoolers to prevent overheating.

3. **Skill Dependency** Installing or modifying these heads can be complex, especially for beginners. Proper torque specifications, gasket application, and alignment are critical to avoid issues like leaks or warping. If not done correctly, it can lead to costly repairs.

4. **Compatibility with Older Engines** While the 350 heads are versatile, they may not fit perfectly with older or heavily modified engines without additional modifications (e.g., custom gaskets, spacers, or bolt patterns).

5. **Potential for Salvage Yard Risks** If purchasing used heads, there is a risk of buying heads that have been previously damaged (e.g., cracked, warped, or improperly machined). Inspecting the heads thoroughly or purchasing from a trusted source is crucial.

6. **Limited Stock Performance** The stock heads are not optimized for high performance. Without upgrades, they may not deliver the power or reliability expected in a high-output application. This means additional investment is often required to unlock their full potential.

---

The GMC 376445 5.7L GM 350 cylinder heads are a **strong, versatile, and cost-effective choice** for enthusiasts looking to build or upgrade an LS-based engine. They offer excellent performance potential, especially with aftermarket support, and are widely compatible with a range of vehicles. However, they require **regular maintenance, proper installation, and potential upgrades** to avoid common issues like valve seat wear, warping, or head gasket failures.

For **street or mild performance applications**, these heads are a solid investment with minimal hassle. For **high-performance or forced-induction builds**, they are a great foundation but will need significant upgrades (valvetrain, cooling, porting) to handle the increased stress. The key to success lies in **proper maintenance, quality parts, and careful installation**.

---

- You are building a **reliable, high-performance LS engine** (e.g., 500 600 hp on stock bottom end with supporting upgrades).

- You plan to **invest in aftermarket parts** (valve seats, springs, porting, cooling upgrades) to maximize their potential.

- You have access to **reputable sources** (salvage yards, trusted sellers, or OEM replacements) to avoid damaged or worn-out heads.

- You are comfortable with **basic engine maintenance** or have access to a mechanic experienced with LS engines.

- You are on a **tight budget** and cannot afford the necessary upgrades to keep the heads running reliably.

- You lack **mechanical experience** or access to proper tools for installation and maintenance.

- You are building a **low-power, daily-driver engine** where stock or mildly upgraded heads would suffice (e.g., a 300 400 hp build).

- You cannot verify the **condition of the heads** (e.g., warping, cracks, or previous damage) before purchasing.

**Final Verdict:** These heads are **one of the best choices for LS-based builds** due to their balance of performance potential, availability, and aftermarket support. With the right upgrades and care, they can deliver **decades of reliable service** in both street and high-performance applications. However, they are not a "set-and-forget" solution and require **proactive maintenance** to avoid common failures. For most enthusiasts, the trade-offs are well worth it.

Details:

Rebuilt years ago and have been sitting wrapped in plastic. The product is a 5.7 GM 350 376445 cylinder heads. They may need a little cleaning before install.

part #: 376445 prices

• $80.79-$600.98

specifications cylinderheapar:

• for models: 350
• for makes: Gmc
• mpn: 376445
• type: Cylinder Head
• manufacturer warranty: 1 Year
• items included: Bolts
• vintage part: No

seller cylinderheapar:

• rating: 100.0%
• city: Coatesville, Pennsylvania
• # reviews: 53

payments cylinderheapar:

• other
• wallet: Apple-pay
• credit card: Visa

general cylinderheapar:

• Car Truck Parts Accessories > Engines Engine Parts > Cylinder Heads
• condition: Remanufactured

returns cylinderheapar:

• policy: Returns Accepted
• time: 14 Days
• paid by: Buyer

shipping cylinderheapar:

• type: Calculated
• transit: 3-9 Days
• cost: $83.04
• carrier: UPS
• service: UPS Ground
• class: Standard

offer cylinderheapar:

• quantity: 1
• options: Ship-to-home
• started: April 7, 2026
• availability: In Stock
• sold: 0

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