Mustang MonthlyHow To Engine
Rebuild Autolite 2100/4100 Carburetors
In this day and age of electronic fuel injection, we find it strangely comforting when we walk up to a vintage Mustang at a show or cruise-in and see the age-old mechanical fuel mixer sitting atop the engine's intake manifold. Unfortunately, the old hot rod adage of "bigger is always better" often rules the day when it comes to carburetion (and camshafts, and exhaust, and valve size, and so on!). We regularly see mild 289ci and 302ci small-block Fords wearing 650-750 four-barrel carburetors, all in the name of more performance. However, a carburetor of that size is usually just wasting fuel and giving you poor fuel economy.
Ford spends billions of dollars on engineering their cars with parts designed to work right and last, so we find it ironic when people remove a perfectly well-engineered part to put a lesser quality part in its place. This goes for vintage as well as newer Mustangs. To that end, many people think the original Autolite carburetors fitted to '60s Mustangs are "factory junk" that need replacing with aftermarket carburetors (that usually require a different intake manifold, throttle linkages, PCV connections, and more). In reality, the Autolite 2100 2V and 4100 4V carburetors are well-engineered and thought out pieces that often just need some TLC and service parts to make them factory fresh once again.
If your Mustang is missing its Autolite carburetor, you can find usable cores at most swap meets or online, then simply go through the carburetor with a good rebuild kit, replace any fittings/linkages required, and setup the carburetor's adjustments for fast idle, choke, accelerator pump shot, and more to have an accurate and well-running carburetor that fits, looks the part, and runs efficiently.
If you're looking for a more concours solution, there are several companies, such as Pony Carburetors, where you can have your carburetor professionally rebuilt and tuned, including show quality plating, or simply buy the proper carburetor outright.
The carburetor we're going to crack open here is an older Pony Carburetors-built 4100 4V. The plating and finish are still in great shape, but due to lack of use and today's E10 fuels, the carburetor has started to leak and give starting and driving issues. So follow along as we take our aging 4100 from crusty leaker back to a show-ready atomizer that runs right.