600 CFM Carburetors

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. A 600 CFM carb can work well with engines making 250-450 horsepower depending on the combination of parts and the RPM where it makes peak power. Lots of people think that bigger is always better. Sometimes that is true, but it’s not always the case with carburetors. Choosing too big of a carburetor will cause bad throttle response, poor low RPM operation and it can even cost you top-end power. No amount of tuning will fix this. You would be better off to pick a carburetor that is a little too small. It may cost you a little power on the top end but it will run better in every other range.

Using a CFM Calculator to See if a 600 CFM Carb is Best

The easiest way to match a carburetor to your engine is to use a CFM Calculator. You can enter your engine size in cubic inches and the RPM where your engine makes its max power. It’s important to be accurate about this number since choosing an unrealistic RPM will really throw off the calculation resulting in an oversized carburetor. The CFM calculator will give you a suggestion for a street tuned engine with basic upgrades and a highly tuned race engine. If your engine is somewhere in between then choose a CFM rating in the middle. Carburetor CFM ratings are a measurement of the maximum volume of air that can flow through the barrels. The calculator estimates the volume of air that can potentially move through your engine based on the information you provide.

Mechanical, Vacuum, or Air Valve Secondaries?

With mechanical secondary carbs the secondary butterflies are directly connected to the throttle linkage and open as you press the gas pedal. They are typically used with lightweight race cars with big cams and manual transmissions. Vacuum secondaries have no mechanical connection to the throttle linkage. The secondary butterflies are opened based on a vacuum signal as RPMs increase. They are more suited to heavier street driven cars with automatic transmissions. Air valve secondaries like the Edelbrock Performer are a combination of the two. The throttle butterflies are mechanically connected to the throttle linkage but the secondary barrels are covered with an air valve. The air valve is opened by air flowing into the engine. They offer the reliability of a mechanical secondary with the load sensing capability of a vacuum secondary.

Which carburetor is right for me?

If you’re asking yourself: how do I choose a carburetor?, we have you covered. Summit Racing has 600 CFM carburetors from Holley, Edelbrock, Quick Fuel, FST Carburetors and more. A properly sized and tuned carburetor of any type can work on any engine. It’s critical to pick the right size with a mechanical secondary carb. A vacuum or air valve secondary carburetor can still run pretty well even if it’s slightly oversized or not tuned perfectly.

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