If you're a classic Mustang veteran, you've seen your share of carburetor swaps. Over the years, many original Autolite 4100 and 4300 carburetors have been replaced by any number of aftermarket carbs, primarily the venerable Holley four-barrel. Holleys have provided dependable performance for over five decades, and they are still one of the most popular replacement four-barrels for vintage Mustangs. But what if you're a purist who wants to return to the Mustang's original fuel system?
Because the Autolite 4300, an emissions carburetor, quickly proved unpopular when it replaced the 4100 in 1967, many were replaced by Holley carburetors with their improved performance and solid dependability. The older Autolite 4100, based loosely on the Holley (power valve and accelerator pump design), sits on the same foundation as the Holley four-barrel. In fact, the 4100, depending on how you size it, offers the same performance features (and power) as a comparable Holley 4160. In other words, a 600-cfm Autolite 4100 will deliver roughly the same performance as a Holley of the same size.
We came up with the idea for this article when Thomas Voehringer wanted his wife's '64 1/2 convertible, which has been in her family since new, brought back to factory original condition. What bugged him was the old Holley replacement carb, installed years ago by his father-in-law, on top of his D-code 289-4V engine. That's when we called Jon Enyeart at Pony Carburetors. Jon knew exactly what type of Autolite 4100 to build, right down to configuration and the carburetor identification tag. Jon specified a C4GF-AE or C4AF-C Autolite 4100 with 1.08-inch bores and automatic choke for a '64 1/2 with four-speed manual transmission.
Pony Carburetors sent us this...
Pony Carburetors sent us this C4GF-AE Autolite 4100 four-barrel carburetor properly date coded for Thomas's mid-1964 convertible.
Because Thomas has a four-speed...
Because Thomas has a four-speed manual transmission, there's no anti-stall dashpot. Before leaving Pony Carburetors, the 4100 was run-tested to make sure that it was ready for action.
Virginia Classic Mustang set...
Virginia Classic Mustang set us up with all the trimmings necessary to get Thomas' 289 engine back on the beam with a stock 4100 carburetor. We've opted for thicker four-bore carburetor base gaskets, which are available from Summit Racing Equipment.
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Many years ago, Thomas' father-in-law...
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Many years ago, Thomas' father-in-law installed this replacement Holley 1850 carburetor with electric automatic choke and vacuum secondaries. With the 4100, we'll be using the original heat tube automatic choke.
We began the removal of the...
We began the removal of the old Holley by disconnecting the neoprene fuel hose. Fuel additives are harsh these days, so it's best to hard line your Mustang's fuel system between the pump and carburetor. Because this 64 1/2 was hard lined to begin with, it's an easy fix. From '66-up, Autolite and Motorcraft carburetors had a short length of fuel hose at the carburetor. That's when you use high-pressure fuel injection hose instead of conventional in the interest of safety.
After disconnecting the carburetor...
After disconnecting the carburetor return spring and throttle linkage, the carburetor fasteners are removed using a deep-well 1/2-inch socket. The carb can then be lifted off the intake manifold.
Carburetor spacer and manifold...
Carburetor spacer and manifold contact surfaces must be hospital clean and perfectly true for proper sealing. Vacuum leaks will cause poor performance and lean spots. Even the smallest trace of old gasket will cause a vacuum leak.
Always opt for thicker carburetor...
Always opt for thicker carburetor gaskets in the interest of proper sealing. Never use gasket sealer here. If surfaces are warped, have them milled by a machine shop.
A new PCV valve and molded...
A new PCV valve and molded hose are installed next. Use clamps on both ends. Turn the carburetor spacer hose clamp ends toward the manifold to prevent carburetor interference.
Our restored Autolite 4100...
Our restored Autolite 4100 is positioned in place on top of the carb spacer. Nuts are installed and tightened evenly in a cris-cross fashion. Never overtighten; it could cause warpage or even break the base plate.
Earlier, we mentioned hard...
Earlier, we mentioned hard lining, which is what Ford did prior to the '66 model year. This is your best assurance against ruptured hoses under pressure. When hard lining isn't realistic, opt for high-pressure hoses for fuel injection. They're both pressure and fuel additive resistant. Make sure the fuel line fitting is properly threaded and do not overtighten. Use Teflon tape on fitting threads, then trim the tape.
The throttle rod should be...
The throttle rod should be adjusted to where the throttle is wide open with the pedal on the floor. Word to the wise: We suggest a double throttle return spring installed in the factory location, available from Summit Racing Equipment, which makes things safer should either spring fail.
The Right Stuff
Few people know more about Ford carburetors than Jon Enyeart of Pony Carburetors. Jon's passion for fuel metering systems became his profession nearly three decades ago when he founded Pony Carburetors back in Western New York. These days, Pony Carburetors is located in Las Cruces, New Mexico. If you're searching for the correct factory carburetor for your application, Pony Carburetors can help with outstanding restorations, rebuilds, parts, and cores.
Here's a restored Autolite...
Here's a restored Autolite 4100 carburetor for a '65-'66 Mustang with the 289-4V and automatic transmission. This is the caliber of restoration you can expect from Pony Carburetors. All carburetors are run-tested before shipping.
To get started on the right hoof, begin your effort with Jon's 1955-1973 Ford Carburetor Guide, which is filled with detailed information that will enable you to identify the carburetor you need for your classic Mustang. Once you're armed with the correct information, get on the horn to Pony Carburetors and chat with a carburetor professional who can get you set up with the correct atomizer. You can also visit their website at
www.ponycarburetors.com for more specific information.
What's This Thing Do?
Ever wonder about carburetor parts and what they do? There are no unimportant parts. Each is there for a specific purpose. Carburetors are fitted with certain components that work in unison with specific applications. For example, an anti-stall dashpot slows throttle closure should you come off the gas and brake suddenly in a Mustang equipped with automatic transmission. You won't see an anti-stall dashpot on a manual transmission car. Ever heard of a hot-idle compensator? Looking like a grasshopper, it creates a vacuum leak to raise idle speed when engine temperature gets out of hand.
This is an anti-stall dashpot,...
This is an anti-stall dashpot, a simple sealed diaphragm that slows throttle closure on automatic transmission cars, which prevents stalling.
Here's a hot-idle compensator,...
Here's a hot-idle compensator, which consists of a bimetallic strip consisting of two dissimilar metals that expand and contract at different rates based on temperature. As expansion occurs with heat, bimetallic strips unseat the valve, causing a minute vacuum leak and faster idle, which helps cooling. If your engine is running rough, it could be a faulty hot-idle compensator.