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I've gotten tried of all of the arguments about the CFM capacity of the Autolite 4100s. In December 2002 I took five of them in a local speed shop and put them on Superflow 1020 flow bench. One 4100 had the small 1.08 primary venturi and the rest had the larger 1.12 primary venturi. The small one flowed 441 CFM, the larger ones flowed 503 to 528, averaging 520.
These results were very close to what I expected for the 1.08 but 50 CFM higher for the 1.12. Still the 1.12 does not flow 600 CFM as claimed by some vendors. The testing was done at Charlie's Automotive in Apex, NC. They are an engine builder for the local NASCAR guys. The tests were done on a Superflow 1020 flow bench which is computerized and automatically corrects the output data to standard temperature and pressure. The flow testing was done at the SAE standard for 4 BBL carburetors - 1.5 inches of mercury, which is the same standard used by Holley, Edelbrock and Carter.| Tag or ID Number | Primary Venturi | Primary Bore | Secondary Venturi | Secondary Bore |
CFM test Results
|
| C6AF-E | 1.08 | 1.437 | 1.18 | 1.437 |
441
|
| EDT 84D | 1.12 | 1.562 | 1.18 | 1.562 |
503
|
| EDT-17BR | 1.12 | 1.562 | 1.18 | 1.562 |
523
|
| C4SF-B | 1.12 | 1.562 | 1.18 | 1.562 |
526
|
| C4AF-DG | 1.12 | 1.562 | 1.18 | 1.562 |
528
|
UPDATE 3/20/2025: Many posts on several forums disagree with the above results. The Ford shop manuals for 1968 and 1969 list even lower values that I have above, so the Ford manuals validate my claim that the Auotlite is not a 600 CFM carb.
The 1968 Ford and Mercury shop manual on page 10-87 lists the Max Air Flow of the Police Interceptor carburetor (C8AF-AE) as 467 CFM. Some other specification for this carburetor are Primary and Seconary throttle bore diameters - 1.562, Primary Venturi 1.125, Secondary Venturi 1.187.
The 1969 Ford Shop Manual (for all Ford cars) at the top of page 10-11-04 has one entry for Autolite Carburetors - C8AF-AE, again used on the 428 Police interceptor engines. It gives the same specification for the throttle bores - 1.562, and the same for the Primary Venturi - 1.125, and Secondary Venturi 1.187. The Max Air Flow is a bit higher - 472 CFM.
Max Air Flow values were not given in earlier shop manuals. And the Autolite 4100 was not used in Ford cars after 1969.
The Autolite 4100 series carburetors are very good for their size. The inserts in the venturies the feed that gas into the air stream are similar to that used on the Holley carburetors and do a great job of mixing the fuel. These carbs work well for every day driving at moderate speeds. If you want to get the best gas mileage you can in your daily driver, these can help you do that.