The Autolite 1100 one-barrel carburetor was offered on the 170 and 200ci sixes from '63-'69, in 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. The carb bore size was
1-7/16", however it is commonly referred to as a 1.5" bore.
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 the 1100 carburetors had a Spark Control Valve (similar to a Holley/Autolite/Motorcraft power valve), which was used in conjunction with the Autolite single-point Load-O-Matic distributor. Unfortunately this distributor had no provisions for mechanical advance (centrifugal weights), instead it used venturi vacuum to sense changes in engine rpm. As such, it works OK on stock motors, but falls short as a performance distributor.
In the late 1960's
the Autolite 1100's experienced two significant changes that effected performance. First... the '68-'69 carbs
were downsized to a 1.10-inch venturi to improve emissions, however this resulted in a very noticeable reduction in performance. Secondly.... the infamous Spark Control Valve was eliminated, first in the '66-'67 California emissions carbs, then in all '68-'69 carburetors. As such the distributors incorporated mechanical advance (centrifugal weights) to sense changes in RPM, rather than venturi vacuum.
One important feature you need to understand, is how the choke mechanism works. The 1100 used mechanical linkage to partially open the choke, unlike most other carbs of the era, which used a piston or diaphragm to open (unload) the choke plate once the engine has started. As such, to start the engine you need to depress the throttle pedal 1/3 to 1/2 the way down and leave it there while cranking the engine. You only remove your foot after the engine has fired. Whereas on other carbs of the era, you remove your foot from the pedal to start the engine, but only after pumping the throttle pedal several times.
Autolite 1100 carburetor identification is done by examining the base plate and searching for the Ford part number for initial identification, however a physical inspection is usually required. Prior to '67 all 1100 carbs had one accelerator pump diaphragm. From '67-'69, manual transmission models had one diaphragm, while automatic transmission models had two, with the second diaphragm acting as an anti-stall dashpot. If you see a Spark Control Valve, which looks like a power valve, you have a pre-'68 carb. If you can't find a Spark Control Valve, it's a '68-69 carb. The best way to identify the size, is by checking the venturi's inside diameter ( 1.00, 1.10, or 1.20-inches). Obviously... the larger 1.20 offers the best performance.
If you plan to swap either the stock 1100 carb or the distributor, it is crucial to understand how the 1100 worked in conjunction with the Load-O-Matic distributor. Basically you can swap the dizzy for the later Duraspark II distributors, or an aftermarket dizzy like the DUI, by capping of the Spark Control Valve vacuum port on the 1100 and using manifold vacuum. However if you swap out the carb, thus eliminating the Spark Control Valve, you must swap out the distributor as well.
The stock Load-O-Matic distributors will not function properly with an aftermarket carb such as a Weber, Holley, or any Autolite carb without a Spark Control Valve. For more information we recommend reading our tech article on the Load-O-Matic
Starting in '63 the 1101 was used on the 223ci inline six, in both full sized cars and trucks. It was also used on the 262ci in 64' and on the 250ci in '69, however the following year ('70) it was replaced by the Carter RBS. The 1101 is very similar to the 1100, but it has a larger venturi and a 1-11/16" carb bore, which is commonly referred to as a 1.75" bore. The 1101 utilized a choke unloader piston, similar to other carbs of the era, however the choke cap is only 1-5/8" whereas most other carbs have 2" cap. The 1101 is rated at 140-145cfm.
This carb was noted for it's trouble free design and was considered to be an excellent carb for the early 60's, capable of providing good fuel economy and reliable service. The 1904 was introduced in '52, but wasn't used on our sixes until early 1960, on Falcons and Comets. Then in late '60 and '61 both models came with the 1908. In 1962 the newly designed 1909 was used on Falcon and Comets, as well as Fairlanes. The Falcon carbs came with a manual choke, while the Comets and Fairlanes came with an automatic choke. All three carbs, normally installed on 215/223ci engines, had a slightly smaller bore and venturi for use on the 144/170ci engines. Flow rates were as follows, 130/150/170cfm for the 1904, 135/150cfm for the 1908, and 125/150cfm for the 1909.
Although the Autolite 1100 gets a lot of attention for its extensive use on Ford sixes, it wasn't the only six-cylinder carburetor. Carter is a name normally associated with Chrysler products of the era, but Ford also used its share of Carter carburetors. The Carter YF first saw use on California emissions 170 and 200ci sixes in 1967. In '68-'69 it was used on the 170ci and 240ci sixes. And in 1970, when the Autolite 1100 was phased out, Mustangs got the Carter YF on the 200ci. The Carter YF is a little squat-box one-barrel carburetor with metering rod that functions like the larger Carters. While it's a better carburetor than the Autolite 1100, the YF suffers from a poorly designed accelerator pump. The YF carburetor does not have a Ford part number on the body, so your best shot at identification is the carburetor tag (if it's still there), or the Carter part number (#6051) which is stamped into the main body. Flow rates for the Carter YF's were 150/170/187/200cfm, however only the 150/187cfm carbs were used on our sixes.
The Carter RBS was only used on the 250ci six, from '70-'73. Like the Carter YF, the RBS has a metering rod design, which is actuated by intake manifold vacuum. And like the YF, it also struggles from a poorly designed accelerator pump. For identification, a Carter part number (#2191) is cast into the RBS body. However in 1972 Carter began producing these carburetors with the words "Mfd. by Carter for Motorcraft", which makes them very easy to identify. Only one size was ever produced, which flowed 215cfm.
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