Carter Aluminum Four-barrel (AFB) Carburetors
(includes ID numbers, specifications, and CFM flow rates)

Introduction
This article discusses Carter AFB carburetors and how to gauge CFM based off confirmed examples. The difficulty with Carter AFB carburetors is that very few were ever rated by the factory for CFM and no complete list is available publicly. There are relatively complete lists of carburetor models and what engine they were originally used on, which I have compiled and edited below, but they do not include CFM ratings. However, there are methods to gauge CFM. Of possible interest, see my other technical articles on rebuilding Carter AFB carburetors and on selecting and tuning Carter AFB carburetors.
Carter AFB CFM Specifications
The best way to identify the approximate CFM of AFB carburetors is a mix of the OEM catalog of engines and inductive reasoning using dimensions from known CFMs in relationship to the engine displacement on which the carburetors were originally used. Ideally, I can measure the throttle and venturi bores of the carburetor before purchasing, but many times when purchasing online I am not able to get those exact measurements. When I don’t have those measurements, I do some educated guessing until I have the carburetor in my hands and can mike the venturis.
For example, I know from the dimensions below and the OEM catalog that a 450 CFM 3252S with 1-7/16” square bores was used on early 60’s 383 and low-performance 413 engines. A 470 CFM 3853S with 1-7/16” primary 1-9/16” secondary bores was used on the 273. A 566 CFM 3611S with 1-7/16” primary 1-9/16” secondary bores came on mid-60’s 383 and 426 wedge engines. However, once we get into the 600 CFM range from the known carburetors below, the OEM catalog shows higher performance models of 340s, 413 ram-induction, and 426 Hemis. Putting all this information together, when I am looking for an AFB and don’t have venturi or throttle bore measurements, I can infer that late-50’s and early 60’s AFBs that came on 313, 318, 326, 350, 354, 361, 383, 392, and low-performance 413 engines likely have between 400 and 500 CFM. Mid-60’s AFBs that came on 273, 383, and low-performance 413 engines likely have between 470 and 566 CFM. AFBs that came on 340, high-performance 413, 426 hemi and wedge, and 440 engines likely have 600 CFM and above.
For most single-carburetor stock and mild A-block builds, finding an AFB model from a late 50’s – early-60’s A, B, or low-performance RB engine will be 400 – 566 CFM and a good choice for the engine after properly jetted and tuned. These carburetors will also be a good place to look for dual-quad setups. For higher-performance single-carburetor A-block builds, finding an AFB that came on mid- to late-60’s LA340/RB engines will likely yield 600 – 728 CFM. Once the carburetor is in my hand, I can dial in the CFM using the known throttle bore and venturi dimensions detailed below.
The following Mopar AFB data with CFM come from Paul Cesarine who passed away in 2016 long before his database was finished. He flow-tested these carburetors to confirm their actual flow and was known as a trustworthy source of carburetor information. I have measured and have collected measurements on other AFB throttle bores and have listed them to help those searching, although I do not have venturi diameters for all carburetors. Keep in mind that Carter made hundreds of AFB models for multiple auto makers, so researching other auto maker AFB models can open more options than focusing just on Mopar models.
Confirmed Mopar Carter AFB CFM Data
450 (CFM confirmed)
3252S, 3249S
- Throttle Body Sizes: 1 7/16″ x 1 7/16″
- Venturi Sizes: 1.186″ x 1.186″
Other AFB with throttle bores 1-7/16″ x 1-7/16″ (CFM not confirmed)
- 2448S (dual quad)
- 2787S
- 3253S
- 3257S
460 (CFM confirmed)
3853S
465 (CFM confirmed)
2790S (front dual quad), 3258S (front dual quad)
- Throttle Body Sizes: 1 7/16″ x 1 9/16″
- Venturi Sizes: 1.093″ x 1.125″
470 (CFM confirmed)
3853S, 3854S, 4199S, 4120S, 4294S, 4295S
- Throttle Body Sizes: 1 7/16″ x 1 9/16″
- Venturi Sizes: 1.063″ x 1.250″
475 (CFM confirmed)
AFB 2791S (rear dual quad), 3259S (rear dual quad)
- Throttle Body Sizes: 1 7/16″ x 1 9/16″
- Venturi Sizes: 1.093″ x 1.125″
537 (CFM confirmed)
4298S, 4299S
- Throttle Body Sizes: 1 7/16″ x 1 9/16″
- Venturi Sizes: 1.186″ x 1.313″
566 (CFM confirmed)
3437S
- Throttle Body Sizes: 1 7/16″ x 1 9/16″
- Venturi Sizes: 1.186″ x 1.313″
566 (CFM confirmed)
3611S
- Throttle Body Sizes: 1 7/16″ x 1 9/16″
- Venturi Sizes: 1.186″ x 1.313″
566 (CFM confirmed)
3859S, 3860S
- Throttle Body Sizes: 1 7/16″ x 1 9/16″
- Venturi Sizes: 1.186″ x 1.313″
566 (CFM confirmed)
4130S, 4131S
- Throttle Body Sizes: 1 7/16″ x 1 9/16″
- Venturi Sizes: 1.186″ x 1.563″
Other AFB with throttle bores 1-7/16″ x 1-9/16″ (CFM not confirmed)
- 2797S
- 3256S
- 3478S
- 3611S
- 3614S
- 3856S
- 3871S
- 4133S
- 4742S
- 4911S
600 (CFM confirmed)
3447S
- Throttle Body Sizes: 1 7/16″ x 1 11/16″
- Venturi Sizes: 1.186″ x 1.563″
600 (CFM confirmed)
4139S (Front) 4140S (Rear)
- Throttle Body Sizes: 1 7/16″ x 1 11/16″
- Venturi Sizes: 1.186″ x 1.563″
700 (CFM confirmed)
3705SA
- Throttle Body Sizes: 1 11/16″ x 1 11/16″
- Venturi Sizes: 1.437″ x 1.563′
728 (CFM confirmed)
4326S, 4327S
- Throttle Body Sizes: 1 11/16″ x 1 11/16″
- Venturi Sizes: 1.437″ x 1.586″
Mopar Carter AFB Model, Year, Engine, and Notes (not a complete list)
2448 57 392 |
2650 58 354 |
2651 58 392 |
2686 57 354 |
2787 59 383/413 Automatic |
2790 59 413 2×4 Front |
2791 59 413 2×4 Rear |
2794 59 383/413 |
2797 59 383/413 |
2798 59 413 2×4 Front |
2799 59 413 2×4 Rear |
2805 58 354 |
2806 58 392 |
2836 58 354 |
2854 59 383/413 Police |
2903 60 413 |
2927 60 413 |
2955 Marine |
2991 60 318 |
3108 61 413 |
3134 61 413 |
3247 61-62 318/361 |
3249 61-62 318/361 |
3251 62 413 |
3252 61-62 383/413 |
3253 61-62 383/413 |
3257 62 413 |
3258 62 413 2×4 Front |
3259 62 413 2×4 Rear |
3374 62 383 Police |
3375 62 383 Police |
3437 63 383 Police |
3447 63 413 Ram Induction |
3478 63 383/413 Police |
3505 63 64 413 |
3520 63 383 Automatic (Canada) |
3611 64 383/426 |
3612 64 383 Automatic (Canada) |
3613 64 383 Automatic (Canada) |
3614 64 413 |
3615 64 413 |
3644 64 413 |
3660 Marine |
3705 64 426 2×4 |
3853 65 273 Manual |
3854 65 273 Automatic |
3855 65 383 Manual |
3856 65 383 Automatic |
3858 65 413 |
3859 65 383/413/426 Manual |
3860 65 383/413/426 Automatic |
3861 65 426 2×4 |
3871 65 413 |
4119 66 273 Manual |
4120 66 273 Automatic |
4121 66 273 Manual CA |
4122 66 273 Automatic CA |
4130 66 383/426 Manual |
4131 66 383/426 Automatic 4132 66 383 Manual CA |
4133 66 383 Automatic CA |
4136 64-67 426/440 Manual CA |
4137 64-67 426/440 Automatic CA |
4139 67 426 2×4 Front |
4140 early-67 426 2×4 Rear |
4200 64 383 Automatic Canada |
4294 67 273 Manual |
4295 67 273 Automatic |
4298 67 383 Manual |
4299 67 383 Automatic |
4304 67 273 Manual CA |
4305 67 273 Automatic CA |
4309 67 383 Manual CA |
4310 67 383 Automatic CA |
4311 67 440 Manual CA |
4312 67 440 Automatic CA |
4318 66 383 Automatic CA |
4324 67 426 2×4 Front CA |
4325 67 426 2×4 Manual Rear CA |
4326 67 440 Manual |
4327 67 440 Automatic |
4328 67 440 Manual P/P CA |
4329 67 440 Automatic P/P CA |
4330 68 440 Automatic w/ Air Conditioning |
4343 late-67 426 2×4 Rear |
4402 67 426 2×4 Automatic Rear CA |
4430 68 426 2×4 Front |
4431 68 426 2×4 Manual Rear |
4432 68 426 2×4 Automatic Rear |
4619 69 426 2×4 Front |
4620 69 426 2×4 Manual Rear |
4621 69 426 2×4 Automatic Rear |
4742 70-early-71 426 2×4 All/T Front |
4745 70-early-71 426 2×4 Manual Rear |
4746 70 426 Automatic Rear |
4911 65-69 383/413 |
4969 late-71 426 2×4 Manual Rear |
4970 late-71 426 2×4 Automatic Rear |
4971 late-71 426 2×4 Automatic Front |
6310 Marine |
Aftermarket Carter AFB |
9400 400 CFM |
9410 400 CFM |
9502 500 CFM no choke, GM linkage |
9511 500 CFM Mopar linkage |
9605 600 CFM, manual choke, GM linkage |
9625 625 CFM |
9626 625 CFM |
9627 625 CFM |
9635 625 CFM |
9636 625 CFM |
9637 625 CFM, electric choke carb, Ford linkage |