I've got an Autolite carb and I am trying to figure out the CFM rating. The numbers are C8TF AE and A7L24 at the bottom of the tag. My goal is optimum mileage. Would it be better to keep this carb or go with something else?

 

What is the number on the side of the float bowl ?
There should be a number like 1.21 on the side where the excellerator pump rod is .
Post that number and I can tell you the cfm!

 

There is a star or circle right behind the rod for the accelerator pump. The number inside the mark corresponds to the cfm rating of the carb.

 

The number on the side of the carb is 1.23

 

Ok, that would make it a 356cfm carb. This is a pretty good starting point for a mileage carb. You could trade up to a 500cfm Holley 2BBL, but they do tend to run rich. This carb, freshly rebuilt, and properly adjusted, should do the job.

 

Would the Holley 500 cfm 2bbl give the same mileage and better power gains, of course without my foot to the floor, with normal driving? Also, the 356 cfm carb is fairly common if I remember correctly. Will just about any 356 cfm carb work for me, because I would like to find one with an auto choke.

 

The 350cfm is pretty common- I don't know if the 500 will give you better mileage. Like I said, Holleys tend to run rich, so it may decrease your mileage.