The Carter AFB and Rochester 4GC were used on the 1963 & 1964 Cadillacs. There was not specific body style, or setup you would see one or the other used and will find either on any particular Cadillac. There were specific model #'s and differences and have posted information I have collected over the years. This might not be complete, but includes the notes I have on file and welcome any updates.

According to the 1964 to 1969 Master Parts book page 219,  The 1964 Carter AFB replacement carb was the 3903S.  The 1959 to 1963 Carter AFB was the 3480S.  The difference between the 3480S and the 3903S is the 3903S has a mounting block on the left/driver side rear with scew holes to hold the electric kick down switch used on the TH equipped cars.  I have seen the 3480's continued to be used on the 1964's that did not require the switch (62 series and 75 series and commercial chassis that had the older Hydrmatics).

Now what was put on these cars later as they were serviced is a smorgasborg.  I have on hand 3904S, and a couple of SR3656S,...but no 3955S.  If you have an new master parts list it probably shows one of the newer carbs.  This was very common.  For example the 1963 Lo and Hi note horns were larger than the 64 horns, but the 64-69 Master Parts book calls for the 64 style as the replacement for the 63 because they no longer made the 63 style.


Here is a listing of the Carbs I have that were originally used for 1963 & 1964:

1 963 8 390 Carter AFB 3480S 577  (without AC)
1963 8 390 Carter AFB 3481S 577  (with AC)
1963 8 390 Rochester 4-GC 7023030 1122
1963 8 390 Rochester 4-GC 7023031 1122
1964 8 429 Carter AFB 3655S 577  (without AC, used as service replacement carb through 1967) 
1964 8 429 Carter AFB *3656S “AD4” 577 (with AC)
1964 8 429 Rochester 4-GC 7024030 1305
1964 8 429 Rochester 4-GC 7024031 1305

Additional Notes added July 3, 2016

For 1963 the Carter AFB's for cars without AC were 3480S
For 1963 the Carter AFB's for cars with AC were 3481S
The Service (replacement) carb was the 3680S ... at least until sometime in 1967 when the 3903s became the service carb.

For 1964 the Carter AFB's for cars without AC were 3655S
For 1964 the Carter AFB's for cars with AC were 3656S
The Service (replacement) carb was the 3655S

CFM Ratings:

CFM ratings were not listed in the Shop Manuals or Dealer Data Books and Carter was really vague in terms of the Carter AFB which could range from 400 cfm up to 900 cfm from what I have read. 

Rochester 4GC is a bit easier as they only made 3 CFM's during this time period: a 486, 553, and 692 cfm carb. You can compare the venturi and main bore diameters (1 1/8 1 15/32 / 1 7/16 1 11/16) to quickly lock in on the fact it was a 553 CFM carb. Since the specs for 63 and 64 are the same you pretty much assume the carbs are the same CFM rating.

As far as the Carter AFB, I had done some research that let me to believe their carb was a 575cfm. There were tons of model # but looking at later ones with CFM rating seemed to narrow it down to 500 CFM to 575 CFM, with the 575 CFM being the closer rating.

Example Pictures:

Carter AFB Carb:

Gaskets & Shim Installation:
--> for Rochester 4GC it is intake, gasket, insulator, gasket,  carb.
--> for Carter AFB it is intake, gasket, insulator, gasket, shim, carb.
Here are the installation instructions you will find in the shop manual in the Carburetor Removal and Installation section (page 10-11, section 20.b. in 1963 manual; page 8-17, Section 27.b. in 1964 manual). 

Rochester 4GC Pictures:

Misc Pictures:

Here are a couple of pictures showing the 1964 Carter AFB with the Kickdown Switch for theTurbo Hydramatic equipped body styles:

Here is the top and bottom of the Intake to Carburetor Insulator:

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Comment by Norman Silverman on January 10, 2019 at 9:17pm

Just sent you an email. Happy to purchase them from you!

Comment by Norman Silverman on January 10, 2019 at 9:11pm

Much obliged !

Comment by Jason Edge on January 10, 2019 at 8:22pm

For the Carter AFB I sell the Fel Pro 60034. It takes 2 of these gaskets, one below and one above the insulator. (For Rochester carbs, use the Fel-Pro 9770). I have been selling both new for many years for $5 each. If you have trouble finding a gasket and want one of mine email me at

Here is a picture of the FelPro gasket I sell for the Carters:

Here is the Fel Pro 9770 for the Rochester 4GC:

Comment by Norman Silverman on January 10, 2019 at 8:00pm

Need to know which carburetor manifold gaskets to buy. I am replacing my original 3656S carburetor with another (rebuilt) 3656S carburetor. Do I buy the ones that are a match to the spacer shown here, or do I buy the old kind that have just the four barrel holes in them?


Comment by Tony and Ginny 429 on December 22, 2017 at 6:58pm
Truly an abundance of food For the holidays

My heritage is Sicilian and will always have more food to eat and drink than the people can consume that are attending
Some of the traditional homemade holiday food are just the best and exciting to see again every year
i was taught ( without words- by example ) to never take the last piece of anything on the table out of respect to the others eating there

Enjoy --the food the family and the egg nog ( Russ ) --Merry Christmas
Comment by Anders on December 22, 2017 at 1:35pm

"smorgasborg" mentioned above is Swedish for a buffet. Smörgåsbord is actually two words; smörgås = sandwich and bord = table. If you want to break it down further you can take the word smörgås apart as well. Smör = butter and gås = goose.

So the conclusion is that the word smorgasbord is used in the sense of a buffet but in reality means sandwich table or butter goose table. Did it make sense?

Smörgåsbord is common throughout the year but is mainly served before and during Santa Claus, then called julbord (Santa table).

Meatballs, ham, small sausages, various cabbage, eel, pickled herring in more than a thousand ways... Basically everything you could think of and some more will end up on the table. Most people eat to much and there has been cases where people ate to much and died. Alcohol is also a very big part.

We drink something called julmust. Coca Cola doesn't really like that we prefer julmust so they run adds aggressively on the tv trying to change our minds. My daughter would never ever drink Coca Cola during Santa times. For her its julmust every day.

Some serious pictures of Smörgåsbord aká Julbord

Comment by Bill Bunch on June 25, 2016 at 10:07am

Thanks for that advice.  I'll definitely check the plugs.  Something is definitely out of whack.  It uses a gallon of fuel just getting to the end of the driveway.  It was always a bit thirsty, but not that bad.

Comment by Tony and Ginny 429 on June 24, 2016 at 4:45pm
When i put the 1406 on my 64 429 engine ,the carb had to be rejetted for the mixture to be correct
The engine was running lean before the carb was rejetted
Lean is not good ,creates excessive heat ,a bad thing
Pull your plugs to examine there color
They should be burning a brown paper bag color if correct
White is lean ,darker color is richer burning plugs
Rejetting and carb adjustments can only be done when all other engine issues have been corrected and specs are on point
They are the last adjustments made to tweek the engines performance ,and will max out performance as the cyliners are burning perfect ,if the plugs are burning the correct color
Comment by Russ Austin on June 23, 2016 at 9:06pm

I have carb adaptor rings, specifically made for this swap.  They are  50.00 plus shipping.

email m at 

Comment by Bill Bunch on June 23, 2016 at 4:07pm

My 64 Series 62 has been "upgraded" to the Edlebrock 1406 by my mechanic.  It runs great but the air cleaner housing no longer fits because the 1406 has a wider mouth than did the original carburetor.  I see carburetor rings sold by some manufacturers but they seem to just elevate the air filter housing.  I see none that adapt from the larger ring of the carb to the smaller air cleaner housing.  How have others handled this difference?  I really don't want to do with an aftermarket air cleaner.  I'm trying to stay as close to stock as possible.


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