Upgrading a 318 Mopar engine with a 4 barrel carburetor can unlock significant power and throttle response. But with so many options from different brands, choosing the right one requires careful research. We compared manufacturer specifications, industry standards, and aggregated owner feedback to evaluate the top contenders. This guide breaks down the strengths and weaknesses of each carburetor to help you make an informed decision.
| Photo | Product | Score | Buy |
|---|---|---|---|
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Edelbrock 1406 Performer 600 CFM Best Overall for Street 318 600 CFM, electric choke, manual secondary, aluminum construction |
9.0 | 🛒 Check Price |
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Holley 0-80457S Street Avenger 670 CFM Best for Performance Upgrades 670 CFM, electric choke, vacuum secondaries, dual-feed fuel bowls |
8.7 | 🛒 Check Price |
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Demon 1901 Speed Demon 625 CFM Best for Precision Tuning 625 CFM, mechanical secondary, annular boosters, billet metering blocks |
8.4 | 🛒 Check Price |
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Summit Racing SUM-M08603 600 CFM Best Budget Option 600 CFM, electric choke, vacuum secondaries, standard flange |
8.1 | 🛒 Check Price |
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Holley 0-1850C 600 CFM Best Classic Holley Replacement 600 CFM, manual choke, vacuum secondaries, single-feed |
8.3 | 🛒 Check Price |
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Edelbrock 1405 Performer 600 CFM Best Manual Choke Alternative 600 CFM, manual choke, manual secondary, aluminum |
7.8 | 🛒 Check Price |
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Quick Fuel Technology QFT-SS-650-VS 650 CFM Best for Modified 318 Engines 650 CFM, vacuum secondaries, electric choke, polished aluminum |
7.3 | 🛒 Check Price |
1. Edelbrock 1406 Performer 600 CFM: Best Overall for Street 318
In our evaluation, the Edelbrock 1406 Performer stands out as the most balanced 4 barrel carburetor for a 318 used primarily on the street. Its 600 CFM flow rating matches the engine’s air demands at moderate RPMs, and the electric choke ensures fuss-free starts. Owner feedback consistently praises its out-of-box calibration for stock 318s, requiring minimal tuning. The aluminum body is both lightweight and resistant to fuel corrosion, adding to its durability.
However, this carburetor has limitations for those seeking maximum power. The manual secondary linkage opens progressively, which is great for street manners but can feel sluggish at wide-open throttle compared to vacuum secondaries. If you plan heavy towing or frequent high-RPM operation, a 650 CFM model might serve better. Also, the fuel inlet location may interfere with some air cleaner setups, so check clearances before purchase.
- Tuned for stock to mild 318 engines with excellent drivability and smooth idle
- Electric choke provides reliable cold starts without manual adjustment
- Durable aluminum body resists corrosion and weighs less than cast iron
Pros: Easy bolt-on with no adapter needed for stock spread-bore intakes; Consistent performance across temperature ranges
Cons: Not ideal for high-RPM or race applications; secondaries open slowly
2. Holley 0-80457S Street Avenger 670 CFM: Best for Performance Upgrades
The Holley Street Avenger 670 CFM is a popular upgrade for 318 owners who want more aggressive performance without sacrificing street manners. Its vacuum secondaries adjust to engine demand, delivering a noticeable kick when you floor it. In our research, owners report significant gains in horsepower and torque compared to the stock 2 barrel, especially when paired with a mild cam and headers. The dual-feed fuel bowls ensure consistent fuel pressure during hard acceleration.
That said, this carburetor demands more attention than the Edelbrock 1406. Many owners note that out-of-box tuning is necessary to eliminate hesitation or rich spots. The metering block and power valve may need adjustment for specific engine combos. If you prefer a set-and-forget solution, this may not be the best choice. Also, the higher CFM rating can be overkill for a stock 318 with restrictive exhaust, potentially reducing low-end torque.
- Vacuum secondaries provide smooth transition and adjust to engine load
- Dual-feed fuel bowls improve fuel delivery under high-demand conditions
- Includes quick-change vacuum secondary spring kit for easy tuning
Pros: Excellent throttle response and power increase over stock 2 barrel; Comes with detailed tuning instructions for DIY enthusiasts
Cons: Requires careful tuning for optimal idle and part-throttle cruise
3. Demon 1901 Speed Demon 625 CFM: Best for Precision Tuning
The Demon 1901 Speed Demon is a favorite among enthusiasts who enjoy fine-tuning their carburetor. Its 625 CFM rating is well-suited for a mild 318, and the annular boosters deliver crisp throttle response. In our evaluation, this carburetor shines when you want to dial in the air-fuel ratio for maximum power. The billet components add durability and allow for replacement of wear items without buying a whole new carburetor.
However, the mechanical secondaries can be abrupt on the street, making part-throttle driving less smooth. This carburetor is best for those who aren’t afraid to adjust jets, air bleeds, and floats. Many owners report that out-of-box tuning is essential, and it can be frustrating for casual users. If you simply want to bolt on and drive, consider a vacuum secondary model. Also, the lack of a choke (manual or electric) on some versions may be inconvenient for daily drivers.
- Annular boosters improve fuel atomization for better throttle response
- Mechanical secondary linkage offers instant full-throttle power
- Billet metering blocks and baseplate for precise airflow control
Pros: Highly tunable with interchangeable air bleeds and emulsion jets; Compact design fits tighter engine bays
Cons: Not for beginners; requires significant tuning knowledge
4. Summit Racing SUM-M08603 600 CFM: Best Budget Option
The Summit Racing SUM-M08603 offers a cost-effective entry into 4 barrel carburetion for the 318. It delivers consistent performance for street use, with a 600 CFM rating and vacuum secondaries that mimic the behavior of more expensive carburetors. In our research, it is praised by budget-conscious builders who need a functional upgrade without breaking the bank. The electric choke is a welcome feature at this price point.
However, durability is a concern. Some owners report minor fuel leaks from the gaskets after extended use, and the throttle shaft bore may wear faster than on Holley or Edelbrock units. This carburetor is best for occasional use or budget builds where reliability is not the top priority. If you plan to drive the vehicle daily or push it hard, investing in a higher-end carburetor is advisable.
- Affordable price with reliable performance for daily driving
- Electric choke for easy cold starts
- Vacuum secondaries provide smooth power delivery
Pros: Great value for the money; Direct replacement for many 2 barrel to 4 barrel conversions
Cons: Less durable than premium brands; some reports of fuel leaks
5. Holley 0-1850C 600 CFM: Best Classic Holley Replacement
The Holley 0-1850C is a classic that has powered countless Mopar engines, including the 318. Its 600 CFM vacuum secondary design is well-mated to stock and mildly modified 318s, offering reliable performance. In our comparison, this carburetor’s strength lies in its simplicity and rebuildability. You can find parts at any auto parts store, and many mechanics are familiar with its tuning. The cast-iron version is very durable, though heavier than aluminum.
However, the manual choke (on this version) requires reaching under the hood to start the engine, which is a drawback for daily drivers. An electric choke conversion is possible but adds cost. Some owners also note that the single-feed fuel inlet can be restrictive at higher fuel demands, though it’s fine for street use. If you want a no-fuss daily driver, consider the electric choke version. This carburetor is best for restoration projects or those who enjoy hands-on tuning.
- Proven design with millions in service; easily rebuildable
- Vacuum secondaries for smooth street driving
- Available with manual or electric choke options
Pros: Tons of aftermarket support and tuning parts; Durable cast-iron construction (aluminum versions also available)
Cons: Manual choke can be inconvenient for daily driving
6. Edelbrock 1405 Performer 600 CFM: Best Manual Choke Alternative
The Edelbrock 1405 is essentially the same carburetor as the 1406 but with a manual choke. For those who prefer simplicity or have a classic vehicle where a manual choke is period-correct, this is a solid choice. It offers the same 600 CFM flow and smooth street performance. In our research, owners who use their 318 for weekend cruising or track days appreciate the manual control over the choke.
However, the manual choke is a significant drawback for daily use. You must remember to set it and then turn it off as the engine warms, which can be inconvenient. Also, the manual secondary linkage can be too aggressive for some drivers, leading to bogging if opened too quickly. This carburetor is best for those who prioritize cost savings or authenticity over convenience. If you drive your 318 regularly, spend a little more for the 1406 with electric choke.
- Same solid performer as the 1406 but with manual choke
- Manual secondary linkage for driver-controlled opening
- Lightweight aluminum body resists corrosion
Pros: Lower cost than the electric choke version; Reliable and consistent once tuned
Cons: Manual choke requires driver intervention on cold starts
7. Quick Fuel Technology QFT-SS-650-VS 650 CFM: Best for Modified 318 Engines
The Quick Fuel Technology QFT-SS-650-VS is designed for 318s that have been modified with a camshaft, headers, and a free-flowing intake. Its 650 CFM rating can support higher RPM power, and the vacuum secondaries help maintain street manners. In our evaluation, it works well when the engine can use the extra airflow, but it is not a drop-in upgrade for a stock 318. Owners with mild builds have reported a noticeable performance gain above 3000 RPM.
However, on a stock 318, the 650 CFM can actually hurt low-end torque and throttle response due to reduced air velocity. Tuning can mitigate this but may not fully solve it. Additionally, some owners have reported quality control issues, such as sticky floats or misaligned gaskets. This carburetor is best for experienced builders who have already upgraded other engine components. For a stock 318, choose a 600 CFM model instead.
- Higher CFM rating suitable for cammed and head-worked 318s
- Vacuum secondaries provide smooth power delivery
- Polished finish adds engine bay aesthetics
Pros: Great for engines with upgraded intake and exhaust; Adjustable vacuum secondary spring for tuning
Cons: Over-carbureted for stock 318; may cause poor low-end response
Frequently Asked Questions
What size 4 barrel carburetor is best for a stock 318?
For a stock 318 with a 2 barrel intake, a 600 CFM carburetor is generally the best match. It provides a good balance of airflow and velocity for low-end torque and mid-range power. Going too large (650 CFM or more) can reduce throttle response and fuel efficiency. However, if you have a mild cam, headers, and a free-flowing exhaust, a 650 CFM carburetor may be beneficial.
Do I need an adapter to install a 4 barrel carburetor on my 318?
Most 318 engines came with a 2 barrel intake manifold. To install a 4 barrel carburetor, you will need a 4 barrel intake manifold or an adapter plate. An adapter allows you to mount a 4 barrel carburetor on a 2 barrel manifold, but it may restrict airflow. For best performance, we recommend upgrading to a proper 4 barrel intake manifold.
What is the difference between vacuum secondary and mechanical secondary carburetors?
Vacuum secondary carburetors open the secondaries based on engine demand, providing smooth power delivery and good drivability for street use. Mechanical secondary carburetors open the secondaries directly with the throttle linkage, offering instant full-throttle response but can be abrupt on the street. For a 318 daily driver, vacuum secondaries are usually preferred. For race or high-performance builds, mechanical secondaries may be chosen.
How do I tune a 4 barrel carburetor for my 318?
Tuning involves adjusting the idle mixture screws, float level, and possibly changing jets and metering rods (on Edelbrock) or power valves and jets (on Holley). Start with the manufacturer’s baseline settings, then adjust based on your engine’s vacuum reading, spark plug color, and driving feel. For precise tuning, an air-fuel ratio gauge is recommended. If you are new to carburetors, consider a model with an electric choke and pre-set calibration like the Edelbrock 1406.
Can I use a 4 barrel carburetor on a 318 with stock cam and exhaust?
Yes, you can, but the gains may be modest. A 4 barrel carburetor will improve throttle response and top-end power, but the stock cam and exhaust restrict overall airflow. You will still see a noticeable improvement over the stock 2 barrel, especially in mid-range power. For maximum benefit, consider upgrading the intake manifold, camshaft, and exhaust system as well.
Our Verdict
After researching and comparing the options, the Edelbrock 1406 Performer 600 CFM earns our top pick for most 318 owners. It offers the best balance of performance, ease of installation, and reliability for street-driven vehicles. For those seeking more aggressive performance and willing to tune, the Holley Street Avenger 670 CFM is a strong runner-up.
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