ROCHESTER 7040255 Quadrajet W-31

( Manufacturer Part Number: 7040255 ), ( Choke Type: Mechanical ), ( Type: Carburetor ), ( Mounting Flange Type: Spread Bore ), ( Manufacturer Warranty: 1 Year ), ( Items Included: Gasket ), ( Features: Quadrajet ), ( Country/region Of Manufacture: United States ), ( Vintage Part: Yes ), ( Performance Part: No )

Review ROCHESTER Quadrajet W-31

The Rochester Quadrajet W-31 is a high-performance carburetor designed for applications where power and efficiency are paramount. This carburetor is part of the Quadrajet series, which is known for its ability to deliver precise fuel delivery and excellent idle quality.

The W-31 model is specifically engineered for use with small-block Chevrolet and GMC engines, making it an ideal choice for hot rods, muscle cars, and other performance applications. It features a quad-barrel design, which allows for increased air flow and fuel delivery compared to traditional single or dual-barrel carburetors.

One of the most notable features of the Rochester Quadrajet W-31 is its vacuum secondary system. This system utilizes four small secondary throats, which are activated by engine vacuum. This design helps to ensure that the carburetor delivers the optimal fuel mixture under a wide range of engine speeds and loads.

Another important feature of the W-31 is its adjustable idle mixture screws. These screws allow the user to fine-tune the carburetor's idle mixture, ensuring that the engine runs smoothly and efficiently at low RPMs. Additionally, the carburetor comes with adjustable primary and secondary idle jet kits, making it easy to customize the idle mixture to specific engine conditions.

The W-31 is also designed with ease of installation in mind. It comes with a tapered bore design, which helps to ensure a good seal between the carburetor and the intake manifold. Additionally, it features a removable float bowl, which makes it easier to access the internal components for adjustments or maintenance.

Overall, the Rochester Quadrajet W-31 is a high-performance carburetor that delivers precise fuel delivery and excellent idle quality. Its vacuum secondary system and adjustable idle mixture screws make it a versatile and customizable solution for small-block Chevrolet and GMC engines. Whether you're building a hot rod or restoring a classic muscle car, the W-31 is a carburetor that will help you get the most out of your engine.

Pros and Cons of buying a Rochester 7040255 Quadrajet W-31 Carburetor

The Rochester 7040255 Quadrajet W-31 is a popular carburetor model known for its high-performance capabilities. However, like any other automotive component, it comes with its pros and cons. In this analysis, we will discuss the advantages and disadvantages of purchasing a Rochester 7040255 Quadrajet W-31 carburetor.

1. Superior Fuel Efficiency: The Quadrajet W-31 carburetor is renowned for its excellent fuel economy. Its advanced design ensures optimal fuel-air mixture, leading to improved engine performance and reduced fuel consumption.

2. Smooth Idle: This carburetor provides a smooth idle, which is crucial for a comfortable driving experience. It minimizes engine vibrations and ensures a steady engine speed.

3. Powerful Performance: The Quadrajet W-31 is capable of delivering impressive power output, making it an excellent choice for high-performance applications. It can effectively handle large engines and provide a noticeable improvement in engine response.

4. Reliable: The Rochester Quadrajet carburetors have a reputation for durability and reliability. They are built using high-quality materials and robust designs, ensuring longevity and consistent performance.

5. Easy to Tune: The Quadrajet W-31 is relatively easy to tune, allowing users to optimize its performance according to their specific engine requirements.

6. Versatile: This carburetor is compatible with a wide range of applications, including both gasoline and diesel engines. This versatility makes it a popular choice among automotive enthusiasts.

1. Complex Design: The Quadrajet W-31's complex design can make it difficult to install and maintain compared to simpler carburetor models. It may require the help of a professional mechanic or extensive DIY knowledge.

2. Expensive: The Rochester 7040255 Quadrajet W-31 is a premium carburetor, and its price reflects its high-performance capabilities. It may not be an affordable option for those on a tight budget.

3. Sensitive to Modifications: The Quadrajet W-31 is a finely tuned carburetor, and any modifications, even minor ones, can significantly impact its performance. Proper tuning and careful adjustments are essential to ensure optimal performance.

The Rochester 7040255 Quadrajet W-31 carburetor offers impressive power, fuel efficiency, and smooth idle, making it an excellent choice for high-performance applications. Its reputation for durability and reliability further adds to its appeal. However, its complex design, sensitivity to modifications, and high price may deter some potential buyers. Ultimately, the decision to purchase the Quadrajet W-31 carburetor depends on individual preferences, budget, and performance requirements. If you prioritize powerful performance and fuel efficiency, this carburetor might be worth the investment.

Details:

7040255 W-31 carburetor. The unit is restored and 100% built to factory standards at a cost of $700. This unit was restored and rebuilt to 1970 W-31 factory Specs by John Herald of Old's Motion. The date is a 1971 so its either service replacement which what I was told when purchased by John or re -stamp.

part #: 7040255 prices

• $42.95-$3500.00

specifications carbcoon:

• for makes: Rochester
• mpn: 7040255
• choke type: Mechanical
• type: Carburetor
• mounting flange type: Spread Bore
• manufacturer warranty: 1 Year
• items included: Gasket
• features: Quadrajet
• country/region of manufacture: United States
• vintage part: Yes
• performance part: No

seller carbcoon:

• # reviews: 139
• rating: 100.0%
• city: Rehoboth, Massachusetts

offer carbcoon:

• options: Ship-to-home
• started: September 7, 2025
• sold: 0
• quantity: 1
• availability: In Stock

returns carbcoon:

• policy: No Returns

shipping carbcoon:

• transit: 4-10 Days
• service: USPS Priority Mail
• class: Expedited
• type: Calculated
• carrier: USPS
• cost: $0.00

general carbcoon:

• Car Truck Parts Accessories > Air Fuel Delivery > Carburetors
• condition: Used

payments carbcoon:

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

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