Jim Smart
October 1, 2009

Ford has been installing electronic fuel injection on Mustangs for the past 26 years. Carbureted Mustangs encompass the rest of the marque's 45-year history - some 21 years of production - which means there were a lot of Mustangs built with old-fashioned carbureted induction. The last Mustang with a carburetor was the '85 Mustang GT, which was fitted with a "no-tamper" Holley 4180.

When the Mustang was introduced on April 17, 1964, there weren't many carburetor types. In fact, all were Autolites. What was used depended upon engine type, automatic versus manual transmission, and where the vehicle was delivered. There wouldn't be a Holley carburetor until 1967 when the popular performance carb saw duty on the 390 High Performance for a short time.

We've known Jon Enyeart at Pony Carburetors for at least two decades. When it comes to classic and late-model carburetor identification and application, Jon's the "go-to" guy for specific information. The news from Jon about Mustang carburetors is generally good, but it isn't always positive because good cores aren't always available. If you have an '80 Mustang with a 255ci small-block and the California emissions-mandatory Motorcraft VV (Variable Venturi) carburetor, you will learn from Jon that these rare emissions carburetors are hard to find and not cheap when you do find them. You could say the same thing about a 780cfm Holley 4160 for the Boss 302 or an Autolite 4100 for a 289 Hi-Po - hard to find and expensive.

If you have a mainstream Mustang with a dime-a-dozen Autolite 2100 two-barrel, the news is generally good-and it won't cost you a fortune.

Autolite 1100
The Autolite 1100 one-barrel carburetor was offered on the 170 and 200ci sixes from '63-'69. There were three venturi sizes - 1.00-, 1.10-, and 1.20-inches. Mustangs had either 1.10- or 1.20-inch depending on model year and configuration. Basic bore size was 17/16-inches. Understanding how the 1100 works takes some imagination, but it isn't much different than any other one-barrel carburetor of the era. What makes it different is how it interacts with the ignition system. The '63-'67 1100 carburetor has a spark control valve (identical to a Holley/Autolite/Motorcraft power valve) which was not used on '66-'67 California emissions or '68-'69 50-state 1100 carburetors. The spark control valve was used in conjunction with the Autolite single-point Load-O-Matic distributor. This distributor did not have a mechanical advance; instead it used venturi vacuum (throttled vacuum) at higher engine rpm.

According to Jon Enyeart, the Autolite 1100 experienced significant changes that adversely affected performance in the late 1960s. In 1968, Ford downsized to a 1.10-inch venturi and eliminated the spark control valve to help reduce emissions. Instead of a vacuum advance, six-cylinder distributors were purely mechanical advance, which hurt performance.

If your six-cylinder Mustang struggles with hesitation, stumbling, and hot starting problems, you're not alone because this is an inherent design flaw in the 1100 carburetor. Pony Carburetors has managed to engineer this problem out of its rebuilds. However, other performance issues remain. For one thing, the 170 and 200ci sixes have an integral log-style intake manifold and cylinder head, making it impossible to achieve uniform fuel distribution to all six cylinders. Cylinders 1 and 6 don't get adequate fuel distribution, resulting in unpredictable idle and stumble on acceleration.

The 1100 carburetor has the same kind of automatic choke found on 2100/4100 carburetors-an exhaust manifold-heated thermostatic coil with vacuum-induced choke unloader to reduce cold-start emissions and spark plug fouling. Six-cylinder Mustangs were never produced with a manual choke.