The Carburetors on a 426 Hemi

The 426 Hemi is probably the most talked about engine in the Chrysler family. One of the topics coming up in conversation is the carburetion. Some people ask, how many carburetors did the 426 Hemi have?

The 426 Hemi had two four barrel carburetors made by the brand Carter. Each Carter AFB carburetor was rated at 625 cfm and was mounted inline, one in front of the other. These carburetors were used on all street Hemi engines from 1966 to 1971.

This article will discuss the carburetors in more detail including part numbers for each year. In addition, find out how the carburetors actually worked.

The following carburetor specifications and facts were learned from my personal experience and research, Mopar engine manuals, webinars, books and articles.

426 Hemi Carburetors

The company brand Carter made all the 426 street Hemi carburetors from the first year in 1966 all the way through to the last year in 1971.

The letters AFB mean aluminum four barrel.

The part numbers for each year are different. The front carb has the same part number for an automatic or manual car.

Other than ’66 and ’67, the rear one has a different part number, one for a manual and one for an automatic.

One of my first thoughts when I saw these carburetors for the first time was, two four barrels on a street engine, are you kidding?

The following are the 426 Hemi Carter carburetor part numbers for each year:

1966

4139S Front
4140S Rear

1967

4139S Front
4343S Rear

1968 Manual

4430S Front
4431S Rear

1968 Automatic

4430S Front
4432S Rear

1969 Manual

4619S Front
4620S Rear

1969 Automatic

4619S Front
4621S Rear

1970 Manual

4742S Front
4745S Rear

1970 Automatic

4742S Front
4746S Rear

1971 Manual

4971S Front
4969S Rear

1971 Automatic

4971S Front
4970S Rear

(CAP) Cleaner Air Package

4137S 1966 Automatic
4136S 1966 Manual
4324S 1967 Front (Manual or Automatic) (CAP)
4325S 1967 Rear (Manual or Automatic) (CAP)

The part numbers are stamped into the base on the front, left side.

Find out about the mythical 426 Hemi DOHC in my article, The 426 Hemi Dual Overhead Cam Engine – The “Doomsday Hemi”

Hemi Carter AFB Build Dates

Depending on the year, the earlier carbs have a build date directly underneath the part number. The later ones have the build date to the left of the part number.

The build date consists of a letter and a number. The letter indicates the month and the number indicates the last number of the year.

The letter I was skipped to avoid someone confusing it with the number 1. The letters in the build date represent the following months:

A= January
B= February
C= March
D= April
E= May
F= June
G= July
H= August
J= September
K= October
L= November
M= December

The numbers in the build date represent the following:

6= 1966
7= 1967
8= 1968
9= 1969
0= 1970
1= 1971

The following are some examples of build dates and what they mean:

J8 indicates September 1968
A9 indicates January 1969
F9 indicates June 1969
C6 indicates March 1966

Other Mopar Carb Number Articles:

Find out the Six Pack carb numbers and date codes in my article, 440 Six Carb Numbers and Holley Date Codes.
Mopar 440 Carburetor Identification and Numbers
413 Max Wedge Carburetor Specs

Also, check out the 426 Hemi fuel pump specifications.

My uncle had two Hemi carburetors on the shelf in his garage. Every time we visited him I would venture into the garage and stare at them. He didn’t know what car or year they were from. He acquired them from someone he knew years earlier.

How They Operate

The 426 Hemi carb linkage is progressive. The rear carburetor is considered the primary carburetor. It has the throttle linkage connected to it. A light, quick tap of the gas pedal will only open the rear carburetor.

The front carburetors are considered the secondary and are attached to the rear carb with a progressive linkage bar. When the throttle is opened up past a certain point, the linkage will open the front carb also.

The secondary carb (front) is not vacuum operated like the outboards on a Six Pack setup.

This can clearly be seen in the video below as the engine is opened up to full throttle during a dyno test.

Read up on the last year of the 426 Hemi and what cars it came in. Check out my other article, The Last Year of the 426 Hemi.

To watch the linkage, fast forward to 11:30. You can watch it from the rear and then directly above.

The car idles off the primary and secondary, not just the rear (primary) one. For the 1966 and 1967 carbs, there is no idle adjustment screw. From 1968 to 1971, there is an adjustment screw.

Both the front and rear have idle mixture screws. The front carb’s idle mixture screws are plugged after 1967 (1968-1971).

The front (secondary) carb has mixture screws to provide fuel to the forward cylinders to prevent a lean mixture.

1970 and 1971 have an idle speed solenoid and adjustment.

The dual floats are adjusted by taking the carb apart. It cannot be adjusted from the outside like a Holley.

The idle is adjusted using the mixture screws and the idle adjustments screws.

The carbs have primary and secondary jets and metering rods.

Find out all the cars which came with the 426 Hemi in my article, What Cars Had the 426 Hemi: Street and Race Hemis.

More Hemi Carb Facts

Both carburetors have their own throttle return spring.
The rear carburetor has the automatic choke.
The linkage is on the driver’s side.
The fuel lines attach on the passenger side.
Each carb has two floats, one on each side.
Each one has an accelerator pump.

Check out all the Hemi engines produced prior to the 426 in my article, Hemi Engines Made Before the 426 Hemi.

426 Hemi carburetors taken apart and rebuilt.

The Carburetors on a 426 Hemi

426 Hemi Carburetors

Hemi Carter AFB Build Dates

How They Operate

More Hemi Carb Facts

Read More 426 Hemi Articles!

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