Carburetor information and help for FOX model airplane engines

Fox Carburetor Indentification and Help

If Duke Fox's engines can be considered unique, his carburetors are, perhaps, even more so. We receive quite a few questions regarding carburetor operation but with so many models, spanning many decades, it sometimes takes several emails to determine exactly which one we are dealing with. We have assembled a photo collection that covers most Fox carburetors dating back several decades. Hopefully, these will serve as a guide to help identify the carburetor on your Fox engine.

For more information on carburetor operating theory, adjustment procedures and modifications, just click on the heading or more info for the carb series you are interested in.

Early 2-Jet Carburetors
While other manufacturers were still offering only simple air-bleed types, Fox was producing more complex fuel metered carburetors. These 2-jet designs were capable of good performance, but were also quite tricky to adjust properly. Don't confuse these with modern 2 "needle" carburetors which are quite different in design and operation!
more info
 For .15BB For .19 - .25

 For .29-.36 size engines For .40-.78 size engines

MKX Series Carburetors
These second generation Fox carburetors operate on the same principle as most modern 2-needle types. Although the concept did not originate with Fox, they are still very much "Fox" in appearance.
more info
 For .15BB For .19 - .25 Bushing 

 For .40 small frame engines.
.19BB and .25BB similar but have
round intake instead of square.
 For .40-.78 size engines.

EZ Series Carburetors

The EZ series replaced the MKX on engines .40 and larger. Although outwardly these appear to be just a simple air-bleed design, they are actually more sophisticated. They also employ a fuel metering system for the midrange as well. The air bleed-screw is provided to fine tune the idle mixture.
more info

 For .40 size engines.  For .45-.74 size engines.

"Improved" 2-Needle Carburetors

Although the EZ series is simple to adjust, there have been some mid-range problems because the metering system is not adjustable. Also, the air-bleed design does not always work well in conjunction with external fuel pumps. To solve these problems, Fox has recently introduced a new 2-needle design. While the outward appearance is similar to the previous MKX series, big improvements have been made to the fuel metering system and needle valve assemblies. Our experience has shown these to work extremely well! So far they are available only for .40 size engines.
more info

   Under development.
 For .40 size engines.  For .45-.74 size engines.


Perry Carburetors

The Perry has long been the most favored aftermarket carburetor. Although not a Fox product we are including it in this section as it makes a great update to almost any Fox engine. more info