Original CFM for a 68 383 H code

[Sixt8Chrgr]

My car has a 1406 Edelbrock 600 CFM carb on it now, and I looked up what the application was on the eddy website. The site says this carb is for economy purposes and best used on smaller displacement engines. When I wind my car out in first gear it is starved for fuel. I now think I know why. The primaries are not big enough? I was considering putting a 750 eddy on the motor. My application is 383 H code, auto, 3.23 rear gear stock setup.
Do you guys think this is a good choice Any suggestions?

What was the original CFM used with the Carter?

[Dans 68]

For your car the original carb would have been a Carter 4401 AVS. I believe the flowrate of this carb was about 700 CFM (based upon the fact that the 440 carb flowed 800 CFM and when you ratio down based upon cubic inches you get 696 CFM). The Eddy should work just fine. Here is some info grabbed from the web fyi:

"Carter AVS - Dodge

The Carter AVS (Air Valve Secondary) is a refinement of the basic AFB design. Whereas the AFB used a velocity valve, which is a counterweighted flap below the secondary venturi, the AVS used an air valve, which is a spring loaded flap above the venturi.  The purpose of the two is similar, but the air valve is adjustable from outside the carb.

When the throttle is opened so that the secondary throttle plates begin to open, vacuum develops under the air valve, slowly pulling it open.  In this way, the air flow is controlled and the mixture is kept from getting too lean if the throttle is opened suddenly.

Carter AVS carbs appeared in 1966 on the 275 HP version of the Chevrolet 327, but were never again used on Chevies after that.  AVS carbs were found mostly on Mopar applications from 1968-1971. The most sought-after AVS carbs are the 800 cfm models found on 440 CID motors.

Recently, Edelbrock has been marketing the Thunder Series AVS carburetor, again reproduced by Weber USA.

Carter did not build a performance version of the AVS after OEM production in the 1971 model year. "

Dan

[Ghoste]

I thought the 383 carbs were a lot smaller?  Wasn't it closer to around 625?  The problem with the Eddycarters is that most of them are calibrated on the lean side (hence their "economy" definition).  I don't know if it's done to get the blessing of the EPA and CARB or what but it seems to be the case with them.
You can mess with the Eddy to fatten up it up and if your 383 is a stocker, this is likely your least expensive solution.  You'll need one of their rod and jet kits for starters.

[Sixt8Chrgr]

Thanks for the replies. I will just tinker with what I have.

Thanks,

[A383Wing]

625 CFM is what was originally on there

[John_Kunkel]

Carter never published CFM ratings for OEM carbs, most numbers quoted are a WAG and are higher than the old clinic literature stated.

[Ghoste]

Do you have any idea what the oem rating might be?

[Sublime/Sixpack]

I always thought the 383 carb was 630 cfm and the 440 carb 750 cfm.

[375instroke]

If your car is starved for fuel, it's not the carb.  Perhaps you mean it's choked, or starved for air.  My car had both problems.  I fixed the fuel problem, now I just have the air problem.  Previous owner put a 1405 on my car.  That's a 600CFM AFB, by Edelbrock's numbers, on my 440.  I have a 4618S for it now.  I've been trying to get people to tell me the throttle bore size of their Edelbrock carbs so I can compare their CFM ratings to the Carter carbs, but nothing so far.  The AVS carbs don't have secondary venturis, so they have a bit more flow than an AFB of the same bore size.

[MoparMotel]

I was wondering the same thing. I have a 68 Charger with an H code 383 magnum that just got rebuilt. Engine got rebuilt back to pretty much stock with the exception of a comp cam. The specs are below. It has the stock carter carb on it which looks like its 625cfm from earlier posts. Is this enough carb for the motor?

Brand      COMP Cams
Manufacturer's Part Number      21-306-4
Part Type      Camshafts
Product Line      COMP Cams Magnum Hydraulic Camshafts
Summit Racing Part Number      CCA-21-306-4
Cam Style      Hydraulic flat tappet
Basic Operating RPM Range      1,800-5,500
Intake Duration at 050 inch Lift      224
Exhaust Duration at 050 inch Lift      224
Duration at 050 inch Lift      224 int./224 exh.
Advertised Intake Duration      270
Advertised Exhaust Duration      270
Advertised Duration      270 int./270 exh.
Intake Valve Lift with Factory Rocker Arm Ratio      0.470 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio      0.470 in.
Valve Lift with Factory Rocker Arm Ratio      0.470 int./0.470 exh. lift
Lobe Separation (degrees)      110
Camshaft Gear Attachment      1-bolt
Intake Valve Lash      0.000 in.
Exhaust Valve Lash      0.000 in.
Computer-Controlled Compatible      No
Grind Number      CRB 270H-10
Quantity      Sold individually.
Notes      Single-bolt camshaft.
Reply

[Sixt8Chrgr]

I have a 1406 on my car.