GM 3940977 Nos Heat Riser Exh Valve General 65-68

( Brand: Gm ), ( Manufacturer Part Number: 3940977 ), ( Part Type: Heat Valve Motor ), ( Country Of Origin: United States ), ( Vintage Part: Yes )

Review GM General Motors Nos 65-68 Heat Riser Exh Valve #3887033 #3940977 fits CAMARO CHEVELLE 396 427

The **GM 3940977 NOS (New Old Stock) Heat Riser Exhaust Valve** for the **1965 1968 Chevrolet Camaro and Chevelle models**, specifically designed for the legendary **396 and 427 cubic inch V8 engines**, represents a meticulously preserved piece of automotive heritage that bridges the gap between classic muscle car performance and modern reliability. This rare component, sourced from the original factory production lines, ensures an authentic fit and function that matches the high-performance standards of the era. The heat riser exhaust valve plays a critical role in the engine s exhaust system by regulating the flow of exhaust gases, optimizing backpressure, and enhancing engine breathing particularly under heavy loads or high RPMs while also protecting critical components from excessive heat. Crafted from high-quality, durable materials, this valve is designed to withstand the extreme temperatures and pressures generated by the powerful **396 CID (396 cubic inch) V8** and the even more formidable **427 CID (427 cubic inch) V8**, which were staples in the muscle car era, delivering raw horsepower and torque. Whether installed in a meticulously restored showroom-ready Camaro or a high-performance street rod, this NOS part guarantees an uncompromising connection to the original performance DNA of these iconic engines. For enthusiasts seeking both authenticity and performance, this exhaust valve is an essential addition to any GM big-block build, ensuring that the spirit of the golden age of American muscle lives on with every rev of the engine.

### **Pros and Cons of Buying a 1969 Chevrolet Chevelle SS 396/427 with Heat Riser and Exhaust Valve (GM Part Numbers 3940977, 65-68 Camaro/Chevelle)**

#### **Pros**

1. **Classic Muscle Car Heritage**

The 1969 Chevelle SS with a 396 or 427 V8 is a legendary muscle car, representing the golden era of American automotive performance. These engines are iconic, highly sought-after, and retain strong collector value.

2. **Strong Engine Options**

- The **396 V8** (375 425 hp in factory form) is a reliable, high-performance engine with a reputation for durability when properly maintained.

- The **427 V8** (425 430 hp in the LS6 form) is one of the most powerful and desirable big-block Chevy engines ever made, offering raw power and a distinctive sound.

- Both engines benefit from extensive aftermarket support, including performance parts, rebuild kits, and tuning options.

3. **Proven Reliability (With Proper Care)**

- When maintained correctly, these engines can last well over 200,000 miles, especially with modern fuel and oil standards.

- The **heat riser** (part 3940977) helps improve exhaust flow and engine performance by reducing backpressure, which can be beneficial for both power and longevity.

- The **exhaust valve** (likely part of the valve train) is a critical component, and keeping it in good condition prevents catastrophic engine failure.

4. **Strong Aftermarket and Restoration Community**

- Parts are widely available, both new and used, making repairs and modifications easier.

- Restoration guides, forums (e.g., Chevy101, MuscleCarReview), and professional shops specialize in these models.

- Classic car clubs and shows provide networking opportunities for owners.

5. **Driving Experience**

- The **4-speed manual transmission** (if equipped) offers a more engaging driving experience compared to modern automatics.

- The **solid lifter engines** (common in 396/427 models) provide a distinctive, aggressive sound that enthusiasts love.

- The **stiff suspension and heavyweight** (especially with a 427) make for a planted, responsive handling experience.

6. **Investment Potential**

- Well-preserved examples, especially with rare options (e.g., LS6, Hurst shifter, or low-mileage), appreciate in value over time.

- Restored models can sell for **$50,000 $150,000 ** depending on condition, options, and rarity.

7. **Customization Opportunities**

- The **396/427 platform** is highly modifiable, from **big-block swaps** (e.g., LS-based engines) to **nitrous kits, superchargers, or turbocharging**.

- Modern **fuel injection upgrades** (e.g., Holley, Edelbrock) can significantly improve performance and drivability.

---

#### **Cons**

1. **High Maintenance Costs**

- **Big-block Chevy engines** require **regular valve adjustments** (every 5,000 10,000 miles for solid lifters) to prevent catastrophic failure.

- **Rod bearings, main bearings, and pistons** wear out over time and may need replacement every **100,000 200,000 miles** if not maintained.

- **Exhaust manifolds, headers, and heat risers** can corrode or leak, requiring replacement (especially in rust-prone climates).

- **Transmission and drivetrain** components (e.g., differentials, universal joints) may need attention if the car has high mileage.

2. **Fuel and Emissions Challenges**

- **Modern fuel standards** (higher octane, ethanol blends) can cause **carbon buildup, valve seat wear, or detonation** in older engines.

- **Emissions compliance** can be difficult if modifying or restoring, as many states require **smog-certified** vehicles for registration.

- **Catalytic converters** (if installed) can restrict exhaust flow and reduce performance.

3. **Rust and Structural Issues**

- Many **1969 Chevelle/SS models** suffer from **frame rust, floorpan corrosion, and body panel deterioration**, especially in snowy or humid climates.

- **Original suspension components** (shocks, springs, bushings) are often worn and may require replacement for safe handling.

- **Body-on-frame construction** means rust can compromise structural integrity, requiring **welding, replacement panels, or full restorations**.

4. **Driving Practicality**

- **Poor fuel economy** (typically **10 12 MPG** for the 396, **8 10 MPG** for the 427) makes daily driving expensive.

- **Heavy weight** (especially with a 427) makes the car **less nimble** on highways and in city traffic.

- **Manual transmissions** (if equipped) require **more effort to shift** compared to modern automatics, which can be tiring on long drives.

5. **Insurance and Storage Costs**

- **Classic car insurance** can be **expensive** (especially for high-performance models like the LS6).

- **Storage fees** (if not driving regularly) add up, and **garage protection** is often recommended to prevent rust and damage.

- **Towing and transport** for shows or events can be costly if not owned locally.

6. **Finding a Reliable Example**

- Many **396/427 Chevelle/SS models** have been **abused, neglected, or poorly restored**, leading to **hidden mechanical issues**.

- **Title issues** (salvage, rebuilt, or flood-damaged) can complicate ownership.

- **Dealers and private sellers** may overcharge for "restored" models that still have **major problems**.

7. **Time and Financial Commitment**

- **Restoring a project car** can take **years** and **$20,000 $100,000 ** depending on condition.

- **Driving a daily project car** is impractical for most owners, as maintenance and repairs are frequent.

- **Opportunity cost** money spent on a classic car could be invested elsewhere for better returns.

---

### **Conclusion**

- **Loves classic muscle cars** and values the **heritage, sound, and driving experience**.

- **Has the budget for maintenance, repairs, and potential restoration**.

- **Plans to drive it occasionally** (or keep it as a **show car**).

- **Is prepared for high ownership costs** (insurance, storage, parts).

However, it is **not a practical daily driver** and requires **significant time, money, and mechanical knowledge** to keep running smoothly. If you re looking for a **reliable, low-maintenance vehicle**, this is **not the right choice**. But if you re a **true Chevy enthusiast** willing to put in the work, it s one of the most **rewarding and exciting** cars to own.

---

### **Recommendation**

- Consider a **lower-mileage, well-documented example** (preferably with a **clean title and service records**).

- Start with a **396 over a 427** (easier to maintain, slightly better fuel economy).

- **Get a pre-purchase inspection (PPI) from a trusted mechanic** specializing in big-block Chevys.

- **Budget for at least $30,000 $50,000** for a **restorable project** (not a fully restored show car).

- Look for a **fully restored example** with **low miles (under 50,000)** and **modern emissions compliance**.

- Prioritize **rust-free frames, suspension upgrades, and a reliable transmission**.

- **Avoid salvage-title cars** unless you re prepared for major repairs.

- Focus on **rare options** (e.g., **LS6, Hurst shifter, ZL1, or low-mileage examples**).

- **Avoid heavily modified or "hot rod" builds** originality holds value better.

- **Join classic car forums** to verify authenticity and condition before buying.

- Consider **renting or leasing a classic car** first to see if you enjoy the ownership experience.

- **Partner with a mechanic** who can help with repairs if you re not hands-on.

You **love the era and want a piece of automotive history**.

You **have the skills, tools, and budget** for maintenance.

You **plan to enjoy driving it** (

Details:

NOS 65-68 Camaro Chevelle BB 396 427 Heat Riser Exh Valve GM #3887033 #3940977, BOX IS NOT PERFECT.

part #: 3940977 price

• $74.99

specifications emissyste:

• for models: 396, 427, Camaro, Chevelle
• brand: Gm
• mpn: 3940977
• part type: Heat Valve Motor
• country of origin: United States
• vintage part: Yes

general emissyste:

• Car Truck Parts Accessories > Exhaust Emission Systems > Other Exhaust Emission Parts
• condition: New other see details

seller emissyste:

• rating: 99.9%
• city: Jersey Shore, Pennsylvania
• # reviews: 2313

offer emissyste:

• best offers: True
• quantity: 1
• availability: In Stock
• sold: 0
• options: Ship-to-home
• started: April 23, 2026

payments emissyste:

• wallet: Google-pay
• other
• credit card: Diners-club

shipping emissyste:

• type: Calculated
• carrier: USPS
• transit: 4-8 Days
• class: Standard
• cost: $8.54
• service: USPS Ground Advantage

returns emissyste:

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

Gm 3940977 Is Similar To:

• 00460734 Acdelco Gm Original Equipment Secondary Air Injection Vacuum Delay Valve (19.8% similar) Stock is updated nightly, so it possible that an item shows in but was already sold. Most items are shipped directly from our supplier to you. 18LIFE cycle status code: 4MATERIAL: plastic maximum diameter: 19. This part fits vehicles made in the following years 1991 , 1994 , 1995 , 1996 , 1997...(March 14th, 2018)
• 10037288 Gm Parts Nos Oem (14.3% similar) ...(December 31st, 2017)
• 10045075 Gm Nos Air Injection Engine Pulse Harness Assembly (18.8% similar) Unknown applications. Verify applications before buying. Nos Gm air injection engine pulse harness assembly for. Part I have no way to test this and it is sold as...(April 22nd, 2018)
• 10293954 Acdelco Gm Original Equipment Canister Vent Valve Control Solenoid (25% similar) Brand new emissions evap vent valve part number...(March 6th, 2018)
• 11518792 Gm Valve Retainer (17.3% similar) This part fits vehicles made in the following years 2013 , 2014 , 2015 , 2016 , 2017 , 2018...(July 17th, 2018)
• 12556259 Acdelco Gm Original Equipment Vapor Canister Purge Valve Hose (26.9% similar) 75END 1 type: straightened 2 inside diameter...(December 12th, 2018)
• 12559015 Acdelco Gm Original Equipment Genuine Vapor Control Valve (21.6% similar) This will depend on the carrier. Software, DVD's, videos and VCR tapes are non-returnable, unless defective. Most carriers take 3-4 weeks to settle a claim...(October 7th, 2018)
• 12570427 Acdelco Gm Original Equipment New Genuine Engine Lh Valve Cover (20.8% similar) 5, classic 3500 crew cab, extended regular cab 1 ton, 2/6 '6 box 3/4 8' 5'8 chassis ton 161. 3L, 8 Cl 3L4 DOORCADILLACCTS2004 Cl 2L1 2 ton, 1500 crew cab, cab long box, standard extended regular 2500 3/4 3500 chassis, 185. 5, 3500 crew cab, extended regular 4 door 1/2 ton, classic 1500 cab long box...(August 2nd, 2018)
• 12573220 Acdelco Gm Evaporative Emissions Vapor Canister Purge Solenoid Valve (23.6% similar) Gm evaporate emissions vapor canister purge solenoid valve off a 2004 GMC envoy best regards al...(April 6th, 2018)
• 12599243 Ac Delco Gm Oem Pcv Valve Hose For 08709 29464 (29.5% similar) Brand new ac Delco Gm oem PVC valve hose before purchasing see the compatibility list to make sure this fits your vehicle...(March 26th, 2019)
• 12638819 Acdelco Gm Original Equipment Vapor Canister Valve (26.3% similar) Our experience will show in every customer that we meet and product ship...(August 3rd, 2018)