make a difference in power as quickly as a manifold and carb swap. You can do a carburetor
and manifold swap in an afternoon and be enjoying the differences by evening. From the
factory, Ford didn’t offer much in the way of factory performance induction packages until the
289 High Performance engine was introduced in 1963.
All 221, 260, 289, 302, 351W and 351C two-barrel engines were equipped with the Autolite
2100 series carburetor from the factory. Beginning in 1972, the Autolite name was abandoned
for Motorcraft, but carburetor basics remained the same from the beginning in 1957 until the
end in the late 1980s. The 2100, and later the 2150, provided excellent service for nearly 30
years. Good rule of thumb is to remember that “2100” and “2150” apply to two-barrel carbs
while “4100” applies to the four-barrel. The 4100 carburetor was introduced the same year as
the 2100 in 1957. The 4100 was replaced by the 4300 in 1967. The Autolite/Motorcraft 4300
four-barrel emissions carburetor will be addressed later.
Though the 4100 didn’t set any land speed records, it is likely the most reliable carburetor ever
made. Likewise for the 2100. The 4100 carburetor offers the same size benefits as any mid-
size Holley 500 or 600cfm four-barrel. However, the 4100 offers greater reliability and longevity
than the Holley. You can install an Autolite 4100 atop your Edelbrock Performer or Weiand
Stealth dual-plane and enjoy greater benefits than you will with the Holley.
Induction systems for these engines is a no brainer. There was one basic cast iron intake
manifold topped with one type of carburetor. The Autolite 2100 two-barrel carburetor was
specific to each application, with no two applications having the same Ford part number.
Identification of these carburetors is straightforward. Throttle bore size is your first visual clue.
For example, a Autolite 2100 big-block carburetor has much larger throttle bores than 2100s
designed for the 221 and 260 engines. So the big-block 2100 carburetor’s throttle plates will
not open to full capacity if installed on the 221/260 in error. Likewise, a small-block carburetor
installed on a big-block in error will dramatically reduce performance.
series two-barrel
carburetor. Look for throttle
bore size cast into the body
(arrow). This is a 1.14-inch
throttle bore for the 289-2V.
(driver’s) side of the carburetor body beginning in the 1960 model year. What you can expect
to see are numbers like .98, 1.01, 1.02, 1.14, 1.23. This is the venturi diameter in inches. The
higher the number, the larger the venturi diameter in inches. The 221ci small-block was fitted
with eight possible 2100 types, all with .98-inch diameter venturis (190cfm ). The 260 and 289ci
engines were fitted with 2100 carburetors with 1.01 (245cfm ) and 1.02-inch (240cfm) diameter
venturis, depending upon application. Venturi size originally depended upon transmission,
vehicle application and original sales district. California emissions carburetors, for example,
were jetted differently. This was also true for vehicles delivered to high elevation areas like
Denver. For 1964, the 289 received a larger throttle bore 2100 with 1.14-inch (300cfm )
venturis. This gave the 289 improved low-end torque.
There are a few things to remember about the 2100. Carburetor identification tags weren’t
used until 1965. The most significant improvements in the 2100 came in 1964—accelerator
pump, choke unloading system (choke piston set-up), and National pipe threads at the fuel line
inlet. More changes came in 1966 with the deletion of the brass fuel bowl vent tubes. In 1970, a
choke unloader diaphragm appeared in the air horn as a means to improved cold engine
emissions performance.
Autolite 2100
carburetor received a
choke pull-off
diaphragm (arrow) for
a cleaner warm-up.
with an Autolite 4100 series carburetor. The 289-4V low-compression engine that was offered
briefly in the Mustang beginning in March of 1964 was fitted with the 4100 series four-barrel
carburetor with 1.08-inch (480cfm ) venturis. For 1965-66, the same basic 4100 carburetor
body was employed with 1.08-inch (480cfm ) venturis. However, the 289 High Performance
utilized a 4100 with 1.12-inch venturis (600cfm ) and a manual choke. Improved air flow
enhanced performance.
carburetor is an outstanding piece -
easy to tune, reliable, and offers good
performance. This carburetor was
used on 289-4V and High Performance
engines from 1963-66, and in 1967
only on the Hi-Po. The 1967 289-4V
engine was equipped with the 4300
carburetor.
Beginning in 1967, Ford set its sights on improved emissions. The Autolite 4300 four-barrel
carburetor was conceived to replace the 4100 as a means to both improved emissions and
performance. The 4300 differed greatly from the 4100 with its slightly larger secondary throttle
bores and smaller primaries. From the start, there were teething problems with this carburetor.
It’s first year out, only one version of the 4300 was implemented at 441cfm—not enough
carburetor in any case. The following year, 1968, a larger 4300, a 600cfm unit, was employed
for specific big-block applications only. The 441cfm 4300 carb was dropped in 1970. In 1974,
the 4300 was replaced by the 4350.
In 1971, the Autolite 4300D yielding 715cfm came into play on certain 351 Cleveland engines—
the Boss 351 and the 351 Cobra Jet. What made the 4300D different from the 4300 was its
spreadbore design, like the Rochester QuadraJet, Carter Thermo Quad and Holley Spread
Bore. The 4300D offered huge quantities of air when power was needed.
a compression throttle
return spring instead
of the pull spring used
through 1970.
it is not interchangeable with any other spreadbore carburetor. This means that manifold and
carburetor are married and must be used together. The key here is to learn how to live
peacefully with this carburetor.
The 4300 and 4300D are identifiable by the Ford part numbers cast into the casting. This
number is located at the base at the left-front of the carburetor if the identification tag has
been lost. Living peacefully with the 4300 takes understanding how it works. Performance
depends upon calibration, adjustment and using the right 4300 for the application—just like
any other carburetor.