I have a 56 with a 57 312 bored 30 over other than that it is stock other than some port work.I am thinking on putting on a new edelbrock carb and would like some input on the cfm that i need .The ones that i am looking at are the #1803 500 cfm and the #1403 500 cfm.Do you think they are enough or should i go to a 650 cfm 

Carl,



You will receive different answers. I use a 390 CFM Holley on my 312 bored .040 over.

I have a mild cam in it stock heads.



You can get by with a 500 CFM or 600 CFM. Jetting will have to be adjusted for your application.



The 390 I'm using is jetted as out of the box and runs fine.



I have heard nothing but good things about the tune-ability of the Edelbrock carbs, I'm a holley guy.



All that being said I'm going to put a 57 dual quad manifold on mine and will probably use the edelbrock 500CFM carbs on it. I want that "old time hot rod look of power".

A Blue thunder manifold will probably be better on power. But I like the looks of dual quads.



Keep "Ying".




  Jim Rowe Elkhorn, NE

Just a suggestion. After you decide on the brand of carb it you choose an Edelbrock. Give their tech line a call or email and have them advise you after you give them all the tech details of your ride. That way if you have issues you will get some help. Pete

I like the Holley 390 on my Y block. I have run 600 (list 1850) and 780 (list 3310) on other engines. Always have had the best service from them. Easy to tune, easy to get parts for, they all work very well. There are lots of options available, like different bowls, stub stacks, etc.



But, I've also run a Carter 670 cfm AFB on all sorts of things. It is a stock 400 hp single quad 409 carb and I've had it since high school. It has run on a 425 Olds, a 454, a 400 Pontiac, and now sits on my 272 Y Block. I got a Carter strip kit for it years ago. You used to be able to get the same kind of kit thru Mopar Direct Connection -- maybe you still can. These kits come with a number of different rods and jets. Now that Edelbrock has taken over production, I see that AFB metering rod springs are available for even more tuning options. This carb works great on everything I've run it on.



I'd go with a 500 if your goal is to have a stock street driver. If you want to heat things up in the future, go with the bigger one. My take would be that you would see a slight increase in "sharpness" and throttle response with the smaller one, and maybe a tad better mileage, too. The big one would offer (maybe) a mile or two an hour better on the top end and room to "grow" if you wanted to cam the motor later on.



I have no gripe at all with an AFB -- they are very nice carbs and I think that they are easier to work on than Holleys. But I do have my reasons for liking Holleys better. I always suggest that it's best to run what you like when faced with a carb brand choice. But as for size, You probably aren't going to go too wrong with either carb, but each will offer a little more for certain uses.

My Little Y Block Page

Thanks to all of you for the replys.I have a carter 500 afb carb on the car now.It runs pretty good but stumbles slightly on a normal start.I changed the accelerator pump setting helped a little but is still there.I am thinking on changing the cam,maybe like the old isky e-2 so might go to the 600 cfm  Thanks again  Carl 

On your stumble, you can also try a larger shooter and/or an increase in the fuel level by raising the floats.  You might also check that the vacuum advance on the distributor is coming in right off of idle also.  If the vacuum advance is not working or is lazy, then a stumble can also be present.  I ran the 500 cfm Carter on my own 272 with great success before going with a 525 cfm Road Demon Jr.

Lorena, Texas (South of Waco)