What Size Carburetor The Ford 390 Needs

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The Ford 390 FE Big Block engine was one of Ford’s most durable. If you have one, chances are you need a carburetor. What carburetor does the Ford 390 need?

In a day when cars ran fast rather than efficient, Ford jumped into the muscle-car pool like a kid doing a cannonball. As part of their attempt to out-muscle (pun intended) the competition, Ford designed the Big Block V8, otherwise known as the 390. The 390 was part of the joint venture with Edsel and was manufactured from 1961 - 1976. It produced enough power to be a top choice among several models, including the Mustang, Cougar, Thunderbird, and Police Interceptor. Today, it is an engine many performance builders love putting in their hotrods.

The size of carburetor that the Ford 390 needs are either a 2bbl or 4 bbl unit producing between 600 - 650 CFM. There is a large quantity of aftermarket support for rebuilding these engines, so parts are plentiful, but they can be expensive.

Let’s face it, long before electronic fuel injection, there were carburetors. The primary job of a carburetor is to sit atop the engine and regulate the amount of the fuel/air mix that gets sucked in. The mix passes through a narrowed chamber, driving it into the intake and to each chamber through an intake valve. If you have previously restored cars, you know that a well-working carburetor is crucial to the success of your engine. Too lean a fuel mixture, the engine sucks in more air than it should, and your car stalls. Too rich, the plugs get fouled up; you smell gasoline rising from the engine, which means no power or even a small ball of fire coming out of the carburetor. The last thing you want to do is pay big bucks for a rebuilt carb or a new one and find out that it doesn’t do the trick. What size of carburetor fits best on the 390?

We have scoured the web and owner forums to explore those questions regarding this essential part of your rebuild to find the answers.

Table of Contents


What is the History of the Ford 390?

The Ford FE (which stands for Ford-Edsel was a joint venture between the two companies to produce a Big Block V8 engine that they could use across many platforms. It was essentially a bored-out 352, a top-rated engine at the time. Most 390s still have a 352 stamp still engraved on the block.

The engine debuted in 1961 across the Ford and Mercury line. The motor found its way into the Galaxie 500, Thunderbird, Cougar, Mustang, and F-series pickup trucks. Ford had good luck with the engine, and numerous entities picked up the motor for buses, commercial trucks, and marine applications. The motor proved to be a solid offering for Ford and became a hit.

The initial 390 offered up 335 horsepower and 427 lb/ft of torque. The output was very impressive in the day, but it wasn’t until a few years later, when the 390 made its way into the Mustang GT, that the engine gained most of its popularity. (Chances are, if you have a GT designation on your 60s Cougar or Cyclone, it may very well have a 390 engine under the hood).

While the Big Block V8 was a capable engine, it didn’t last too long. The engine was phased out of passenger cars in 1971 and continued to be offered as an option in trucks until 1976. The 70s brought a significant emphasis on small block v8s, which were more efficient and less expensive. The public disdain for these bigger V8s and the embrace of smaller, four-cylinder motors sealed the demise.

While the 390 was pretty resilient, it wasn’t without some issues. Owners often complained about valve cover leakage, bent rods, and vacuum leaks near the intake manifolds. Despite these concerns, the 390 FE proved a durable engine that was a blast to drive.

What Should I know Before Buying a Carburetor?

The good news is that plenty of aftermarket carburetors will fit the Ford 390. But it is essential to be armed with some information so you don’t end up purchasing a unit you shouldn’t.

Know the CFM rating

Carburetors are sized by the amount of air and fuel mixture they process in cubic feet per minute. It is always best to consult your owner’s manual for your existing CFM rating on the old carburetor you are replacing. Most forums recommend a carb rated around 600 - 650 CFM for the 390 engine.

The formula for calculating the CFM number is -

CFM = Cubic Inches x RPM x Volumetric Efficiency ÷ 3456.

Most carburetors have list numbers, or the CFM stamped directly onto the carburetor. The number for Autolite/Motorcraft carburetors is found on the side of the float bowl behind the accelerator rod inside a circle. (The second number is the CFM - The first number is the venturi designation referring to the narrowest part of the passage of the unit). For Holleys, the list number is like a VIN and is hand stamped on the choke tower to the right of the vent tube. The list number is usually four-six digits long.

Know The Flange Size

Because different companies make carburetors, you will need to know the flange size for your engine. If you choose the wrong flange style, you won’t be able to secure the carb to the intake manifold.

Know if you want 2bbl or 4bbl?

By inspecting the existing carburetor on the car, you should be able to determine how many barrels it has. A four-barrel carburetor will have four distinct chambers, two primary and two secondaries. The primary barrels work when the engine is idling or revving at low rpm, while the secondary barrels kick in to provide an additional mix of air and fuel when there is a greater demand on the engine, like during acceleration. If you have ever driven an older car and felt it kick into passing gear, that’s a signal that all four barrels are doing their thing.

What Size Carburetor Does the Ford 390 Need?

As mentioned above, depending on what you plan to use the Ford FE 390 you are rebuilding for, most forums recommend a carburetor that puts out about 600 - 650 CFM. If you want a screaming demon, go a bit higher, but anything above 750 won’t make that much difference. (Interestingly, the 390 engine that went into their Police Interceptor produced 600 CFM. In the late 60s, the Shelby had a carburetor that produced 735 CFM).

How Much Does a Carburator Cost?

There is excellent aftermarket support for these rebuilds, so you should not have trouble finding the correct carburetor that will adequately fit your engine. The prices can range from a couple hundred dollars on the low end to over a grand on the high side. A good quality carb will likely cost you somewhere in the middle.

Can I Rebuild the Old Carberator?

It may be possible to rebuild the existing carb on the engine, but most Ford forums (detailed internet sites populated by actual owners helping each other) don’t recommend it. Many have gone through the trouble of paying someone to rebuild a carburetor only to have it work a few times and then go kaput. It is usually best to buy new unless you can find a rebuilt one from a company you trust.