GM 12600821 Ls Heads Int General 260CC 68CC 2.165/1.59

( Brand: Gm ), ( Manufacturer Part Number: 12600821 ), ( Type: Cylinder Head ), ( Material: Aluminum ), ( Vintage Part: No ), ( Country Of Origin: United States ), ( Performance Part: Yes )

Review GM General Motors Ls Chevy Aluminum Heads 260cc Int 68cc 2.165/1.59 Bare Pair

These **Chevrolet 260cc Intake (12600821) cylinder heads** are a high-performance, meticulously crafted component designed to elevate the breathing and efficiency of your small-block Chevrolet engine, particularly those with a 260cc intake manifold configuration. Engineered for the classic **260cc intake port** setup, these heads are forged from **high-quality cast iron**, ensuring durability and resistance to thermal stress under high-performance conditions. The **2.165-inch intake valve** and **1.59-inch exhaust valve** dimensions are optimized for improved airflow, allowing for better combustion and increased horsepower and torque output. The **68cc combustion chamber** volume is carefully calibrated to complement the intake manifold, promoting a more efficient air-fuel mixture and reducing detonation risk. These heads are **bare**, meaning they come without valves, springs, retainers, or rocker arms, offering the flexibility to pair them with upgraded components like stamped steel or titanium valves, coil-over valvesprings, or hydraulic flat-tappet lifters for enhanced performance. Whether you're building a **high-revving street machine, a drag racing engine, or a reliable daily driver**, these heads provide a solid foundation for achieving superior power delivery while maintaining reliability. Perfect for applications ranging from **1955 to 1965 small-block Chevy engines**, these heads are a sought-after upgrade for enthusiasts looking to push their engines to new limits.

### **Pros and Cons of Buying Bare 12600821 GM LS Chevy Heads (260cc Intake, 68cc Intake, 2.165/1.59 Compression Ratio)**

1. **High Performance Potential** These heads are designed for high-revving, high-flow applications, making them ideal for forced induction (turbo/supercharger) or high-performance naturally aspirated builds. The 260cc intake ports and 68cc intake valves allow for significant airflow improvements over stock heads.

2. **Lightweight Construction** The aluminum casting keeps the heads relatively light compared to cast iron, improving engine responsiveness and reducing reciprocating mass.

- High-flow intake and exhaust valves

- Porting and polishing services

- Custom valve springs and retainers

- Performance camshafts and lifters

4. **Compatibility with Modern Engines** The LS platform is one of the most popular in aftermarket tuning, so these heads can be paired with a variety of modern components, from stock LS blocks to high-performance bottom ends.

5. **Potential for High Horsepower** With proper porting, valve training, and supporting modifications (fueling, cooling, etc.), these heads can reliably produce **500 HP** on pump gas and **800 HP** with ethanol blends and forced induction.

6. **Customization Options** Buyers can choose between different valve sizes (e.g., 2.165" intake/1.59" exhaust) to optimize airflow for their specific application (e.g., more aggressive valve sizes for forced induction).

7. **Resale Value** Since LS engines are highly sought after, well-maintained heads in good condition can retain value, especially if they come from a known performance build.

---

1. **High Cost** Bare heads are expensive upfront, especially when factoring in additional components needed for a complete build (valves, springs, retainers, gaskets, porting, etc.). A full performance head setup can easily cost **$1,500 $3,000 ** depending on modifications.

- **Fueling upgrades** (high-flow injectors, fuel pump, ECU tuning)

- **Cooling system improvements** (larger radiator, upgraded water pump, thermostat)

- **Exhaust system** (high-flow headers, catless exhaust for NA builds)

- **Intake system** (high-flow air filter, throttle body, or supercharger/turbo)

- **Lubrication system** (oil cooler, upgraded oil pump)

- **ECU tuning** (to properly map fuel, ignition, and timing)

Neglecting these can lead to **detonation, overheating, or catastrophic failure**.

- **Port matching** (if using a custom block)

- **Valve grinding** (to ensure proper seating and flow)

- **Valve spring upgrades** (to handle higher RPMs and valve float)

- **Retainer and keeper upgrades** (to prevent valve bounce)

DIY porting is difficult for beginners, and professional porting can add **$500 $1,500 ** to the cost.

4. **Potential for Leaks and Gasket Issues** Aluminum heads can develop **warping** over time, leading to head gasket failures if not properly bedded and torqued. LS heads are prone to **warping under high loads**, so proper cooling and torque specs must be followed.

- **Precision torque requirements** (over-torquing can warp the heads)

- **Valve train setup** (proper lash, spring preload, and retainer installation)

- **Sealing issues** (head gaskets, oil control rings, and freeze plugs must be properly installed)

6. **Not a "Set-and-Forget" Upgrade** Unlike bolt-on parts (e.g., cold air intake, exhaust), these heads require **ongoing maintenance**, including:

- Regular valve inspection (for wear or cracks)

- Coolant system checks (to prevent overheating)

- Fuel system tuning (as power increases)

7. **Risk of Overbuilding the Top End** If the rest of the engine (block, crank, rods, etc.) isn t upgraded to match, the heads can become a **weak point**. For example:

- A stock LS3 block may struggle with **800 HP** without reinforcement (e.g., rod bolts, main caps).

- A weak oil pump or cooling system can fail under high loads.

---

### **Conclusion and Recommendation**

#### **Who Should Buy These Heads?**

- **Serious performance enthusiasts** building a **high-RPM, high-flow engine** (NA or forced induction).

- **Turbocharged/supercharged builds** where airflow is critical.

- **Builders with experience** in engine assembly or those willing to invest in professional help.

- **Projects with a budget** for supporting modifications (fueling, cooling, exhaust, tuning).

#### **Who Should Avoid These Heads?**

- **Beginners** who want a simple, bolt-on performance upgrade.

- **Budget-conscious builders** who can t afford the full supporting mods.

- **Those building a daily driver** without plans for forced induction (unless paired with a strong bottom end).

- **People who dislike fine-tuning** (these heads require careful setup).

If you re **committed to a high-performance LS engine** and have the **budget and knowledge** to support them, these heads are an excellent choice for **serious power gains**. However, if you re looking for a **quick, affordable upgrade**, consider alternatives like:

- **Stock LS heads with porting** (cheaper but less potential)

- **Aftermarket heads from reputable manufacturers** (e.g., JE, Edelbrock, or custom ported heads)

- **Turbocharged/supercharged kits** that include heads as part of a complete package

**For the right builder, these heads are a fantastic foundation for a high-revving, high-flow LS engine but they demand respect and proper support.** If you re willing to put in the work, the payoff in **horsepower and reliability** can be substantial. If not, they may end up being an expensive investment with limited returns.

Details:

Aluminum, Untouched, Bare. 260CC Intake, Valve size 2.165/1.590, 68CC Chamber, Angle Plug. GM Heads, 12600821 LS Chevy Square Port PAIR.

part #: 12600821 prices

• $599.99-$7421.21

specifications cylinderheapar:

• for makes: Chevy
• brand: Gm
• mpn: 12600821
• type: Cylinder Head
• material: Aluminum
• vintage part: No
• country of origin: United States
• performance part: Yes

returns cylinderheapar:

• policy: Returns Accepted
• paid by: Seller
• time: 30 Days

seller cylinderheapar:

• city: East Jordan, Michigan
• # reviews: 16187
• rating: 99.8%

shipping cylinderheapar:

• class: Standard
• cost: $93.89
• service: UPS Ground
• type: Calculated
• transit: 3-8 Days
• carrier: UPS

general cylinderheapar:

• Car Truck Parts Accessories > Engines Engine Parts > Cylinder Heads
• condition: For parts or not working

offer cylinderheapar:

• options: Ship-to-home
• availability: In Stock
• started: May 5, 2026
• quantity: 1
• sold: 0

payments cylinderheapar:

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

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