What Size Carburetor Do I Need For A 350 | Carburetor Size Explained

A carburetor can be worn down with use and, at times, might need replacing. When you’re picking out a new carburetor, an important thing you need to consider is the size that you’re picking. It won’t do you any good to pick any size of the carburetor.

So in this article, we’ll be trying to answer the question, what size carburetor do I need for a 350? We’ll also be looking at why choosing the right size for your 350 is important.

What Size Carburetor Do I Need For A 350

Why Does The Size Of Your Carburetor Matter?

The size and power of your carburetor are related. Bigger carburetors will be able to draw in more air and properly mix them with fuel to create combustion. As such, they will be able to provide more power to your vehicle. This will help with your car’s driving ability and acceleration. That’s why before getting a carburetor, you need to ask yourself, how much does a chevy 350 engine weigh.

While this might tempt you into thinking that the bigger the carburetor, the better, that is not the case. Carburetors need to be properly chosen based on certain factors. We’ll also be looking at why a bigger carburetor isn’t always the best choice.

What Factors Affect The Size Of Carburetor You Need?

What Factors Affect The Size Of Carburetor You Need

First and foremost, the most important factor is the vehicle you’re using and its engine. For this article, we’ll be looking at the recommended sizes for a 350 Chevy, but the general rule is that bigger vehicles often require a bigger carburetor. This is because they need more combustion to produce more energy to keep the vehicle going.

Next, the other factor you need to keep in mind is the engine your vehicle is employing. V8 engines have a different demand than V12 engines. Higher horsepower cars will need bigger carburetors to keep up and ensure a smooth performance of the car. Generally, 350 Chevy’s employ V8 engines, but they can be modified to make use of more powerful engines.

Finally, additional accessories like carb spacers can alter the size of the carburetor you need. They usually tend to increase the horsepower of your ability and, as a result, allow you to use a bigger carburetor. 

The Problems of Using A Big Carburetor

While using a big carburetor like does tend to boost the performance of your car especially if it’s paired with LQ4 turbo cam, but it is only up to a certain limit. After a certain point, your car’s engine doesn’t properly keep up with the mixing power of a bigger carburetor. It can end up disrupting your engine’s performance as it can cause it to choke. You may notice your car abruptly stopping and reduced fuel efficiency. And mind you, the carburetor rebuild cost can get pretty high.

So there must be a middle ground, where the size of your carburetor provides you optimal performance but isn’t so big that it causes your engine to choke. This now begs the question of how this particular size is decided to obtain the optimal performance. 

Deciding On the Size of Carburetor

It is possible to come across an estimate on what size of a carburetor you might need for your vehicle. The general rule of thumb is that the size of your carburetor is directly proportional to the volumetric efficiency of your engine. In case you are not aware, volumetric efficiency measures how much of the airflow through the engine. 

The volumetric efficiency is one factor that limits the size of your carburetor. If the efficiency is low, less air is allowed to pass through, and using a bigger carburetor than recommended will cause choking. 

By taking the volumetric efficiency into account and multiplying it with the cc of the engine and the rpm, you can then obtain the CFM  for your required carburetor after dividing the result by 3456. CFM measures the airflow of your carburetor and is often used to determine the size you will need for your car.

Using the formula is one of the best ways to determine what you need for your vehicle. We will be using it to determine the size of the carburetor for your 350. 

What Size Carburetor Do I Need For A 350 

If we are considering a stock Chevy 350 that has been unmodified, we can assume volumetric efficiency to be 80 percent. They make use of 350 CC engines and usually tend to have an rpm of 5500.

Considering these values, the CFM rounds up to 445. So for stock 350s, you will generally want a carburetor rated at around 445 or 450 CFM. For modified ones with higher volumetric efficiencies, 500 CFM carburetors are usually recommended.

It should be noted that the actual values can differ since we are taking some approximations and estimates. You should refer to the proper values of your vehicles to come to a proper conclusion and get a more accurate result.


What size carburetor do I need for a 350? The answer is that in most cases, you will need a 445 or 450 CFM carburetor. Be sure to check the specifications on your vehicle and consult with a mechanic just to be sure.