# FAQ: What Carburetor Do I Need?

## How do I know what size carburetor I need?

The formula for calculating how much CFM (cubic feet per minute) your engine requires is: CFM = Cubic Inches x RPM x Volumetric Efficiency ÷ 3456.

## How do I choose the right carburetor?

To arrive at the most appropriate carburetor choice, there’s a basic formula: engine displacement multiplied by maximum rpm divided by 3,456. For example: a typical 355ci small-block—a 0.030-over rebuild—with a 6,000-rpm max engine speed would work well with a 616-cfm carb ((355 x 6,000) 3,456 = 616.32).

## How much horsepower will a 650 cfm carb support?

So, using your Google-Fu you type “How much power can a 650 cfm carb support?” Well, chances are that you’ll get answers in the 450-470 hp range, but that’s not really the right way to look at it.

## What cfm carb do I need for a 350?

A 600-cfm carburetor may perform quite well on a stock 350 Chevy. However, the minute you start weaving in power adders like a hotter cam, a dual-plane performance intake manifold, and aluminum heads you’re going to need 700-750 cfm.

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## What happens if your carburetor is too big?

If the barrels are too big, the loss of air velocity means the cylinder will not fill to its full capacity. An engine with a carb that is too big will put out less Torque and Horsepower. It will be difficult to drive due to poor low-end torque. If you drag race your car, an oversized carb will produce slow 60 ft.

## How do I know if my carburetor is rich or lean?

Q: How Do You Tell if a Carburetor Is Rich or Lean? A: One way to tell for sure is by “reading” the spark plugs. If the plug tip is white, the mixture is lean. If it’s brown or black, it’s rich.

## How much does a new carburetor cost?

Depending on the extent of service that needs to be performed, this type of service typically costs around \$200 to \$300. If your carburetor needs to be replaced, it may run you between \$500 and \$800 total.

## What can I spray in my carburetor to start my engine?

Remove the air filter and shoot a one-second burst of an aerosol petroleum-based lubricant (not starting fluid, silicone or Teflon spray) directly into the carburetor throat. Try starting. If the engine starts and then dies, that confirms you’ve got a fuel problem.

## What are the 3 types of carburetors?

There are three general types of carburetors depending on the direction of flow of air.

• Types of Carburetors.
• Constant Choke Carburetor:
• Constant Vacuum Carburetor:
• Multiple Venturi Carburetor:

## Does a carburetor spacer add horsepower?

When you stack spacers, you are actually improving their insulation properties, and at the same time you’re getting more horsepower. This type of spacer will increase the velocity of your vehicle’s air-to-fuel charge. This means you’ll build low to mid-range torque.

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## Are carb spacers worth it?

Spacers are said to improve air/fuel vaporization through and out of the carburetor. Anytime the air/fuel charge has to turn sharply coming off the carb, it increases the chance of separating the fuel from the air.

## How much HP does a carburetor add?

After you fix what’s limiting performance, an Edelbrock Performer intake can add as much as 10 HP. The FAQ forum is a good place to ask questions. There are differences between engines and performance improvements.

## What is a 600 CFM carburetor?

A 600 CFM carburetor can be a great choice for a wide variety of engines. They can be a perfect match for a highly tuned race engine around 300 cubic inches all the way up to a street tuned big block.

## Will a bigger carb make my bike faster?

A bigger carburetor alone will not make your bike go faster. In most cases, your bike won’t even start or idle roughly with a carburetor that’s too big. For more power, you should look into a full system performance exhaust and rejetting your carb (not replacing it entirely).

## Can I use any carburetor?

That’s because there is a wide variety of pod filters on the market to fit most any carburetor. If the carb you’re considering has a different size spigot than your current carb, you can always have an adapter ring machined by your local machine shop. Sometimes you can just use a different manifold adapter.