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Old 12-18-2013, 07:47 PM
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AFB with vacuum secondaries

Found something today, I didn't know existed. A carter afb with vacuum secondaries. It's from a 1957 ford fair lane with a 312 engine. Carb is in overall good condition. Got a kit coming from Napa for half of what the carb doctor wanted. The vacuum diaphragm is a little harder to fing and almost as much as the carb doctor kit.

Any body know anything about these carbs. Anything on cfm, reliability?

Numbers is a 2441sa

Keith
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Old 12-18-2013, 08:18 PM
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Got a picture of this?
I have never heard of a vacuum secondary AFB as well.
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Old 12-18-2013, 08:28 PM
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Don't they all need vacuum for the secondary air valve to open?
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Old 12-18-2013, 08:48 PM
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As far as I know, all AFB's use a weight on the secondary throttle shaft with plates that will open the throttle based on the amount of air being pulled in against the weight. You do not want to grind on the weight in an attempt to make the secondaries open sooner. Ask me how I know.

Here's a series of 6 youtube videos by Mike, rebuilding an AFB....

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Old 12-19-2013, 06:00 AM
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I've got it apart right now, kits on the way, carb doctor had the diaphragm for the secondary, as soon as I get it back together I'll post picture. Afb had mechanical secondaries except for a few built by carter for ford. Looks just like an afb only it has a vacuum plenum mounted on the left side as viewed from the front, vacuum supply is ported in from the base of the carb.

Keith
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Old 12-19-2013, 12:57 PM
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Quote:
Originally Posted by blwilliams View Post
Got a picture of this?
I have never heard of a vacuum secondary AFB as well.
Once again, Google Images is your friend:

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Old 12-19-2013, 02:30 PM
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amazing.
Thank you for the picture.
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Old 12-19-2013, 05:10 PM
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I've heard of these before ... believe they were called "AVS" series.

AFB = Aluminum Four Barrel
AVS = Air Valve Secondary


Edit:
AVS carbs appear to have had a second set of butterflies ABOVE the secondaries sort of like a Rottenchester.

Here is an illustrated parts list for your 2441SA

Last edited by 66GMC; 12-19-2013 at 05:36 PM.
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Old 12-20-2013, 04:21 AM
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Quote:
Originally Posted by 66GMC View Post
I've heard of these before ... believe they were called "AVS" series.

AFB = Aluminum Four Barrel
AVS = Air Valve Secondary


Edit:
AVS carbs appear to have had a second set of butterflies ABOVE the secondaries
The AVS does not use vacuum secondaries. The air valve is opened by mass airflow, just like on the Qjet. The AVS is what Ebrock used for their carbs.
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Old 12-20-2013, 09:46 AM
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Ford AFB

Afb's were also used on some 352 inteceptor engines in 58, the dealership rebuilt one for a buddy, and it didn't work. He brought it to me with another kit, after I redid it and followed the adjustment directions in the kit it still did not work right. He was reluctant to let me start doing it my way . the choke unloader didn't work and the back 2 barrels did not open all the way. I think I also changed the accelerator pumps. After I got it done he could romp on the gas and burn rubber. He took it back to the dealership to give the mechanic a test ride. A couple weeks later the mechanic brought me a brand new just sold 63 427 to play with ovenight. It wouldn't keep up with the lighter 426 Mopars.
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Old 12-20-2013, 11:16 AM
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http://www.hotrodders.com/forum/atta...1&d=1387563286


Check here
1957-1967 Carter Model AFB Carburetor
Chrysler and a few other Company's besides Ford had them and the 400 WCFB also had one with the same vacuum pot for the secondarys
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Old 12-20-2013, 12:27 PM
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MOPAR used AVS Carter carburators. Carter did not rate them according to CFM but the 340 CI MOPAR engine use a 625 CFM AVS and the 440 CI MOPAR engines used a 750 CFM AVS carburator. The secondary throttle plates were mechanically operated with a adjustable spring loaded secondary air valve and fuel spray bars above the secondary throttle plates. The Air Valve operation permitted a smooth transition to the secondaries without the benefit of a secondary accelerator pump booster circuit.

Last edited by MouseFink; 12-20-2013 at 12:40 PM.
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Old 02-23-2014, 10:50 PM
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I have been rebuilding my 57 Ford Carter carb and it is exactly like the one you are describing/ pictured. The part I can't find is the dash pot plunger assembly. It is the accelerator looking part directly opposite to the accelerator pump. Did the kit you found come with that piece? What does it actually do? It seems to plung into a closed well and doesn't force fuel anywhere.

Thank You,
Dan
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Old 02-24-2014, 08:49 AM
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Quote:
Originally Posted by Cabbie View Post
I have been rebuilding my 57 Ford Carter carb and it is exactly like the one you are describing/ pictured. The part I can't find is the dash pot plunger assembly. It is the accelerator looking part directly opposite to the accelerator pump. Did the kit you found come with that piece? What does it actually do? It seems to plung into a closed well and doesn't force fuel anywhere.

Thank You,
Dan
I can't help you with locating a part, but the dashpot is simply a damper for the choke plate. It's comparable to the external vacuum break diaphragms that are more common, but the function is the same. GM used a similar dashpot on the original Qjets to damp the opening of the secondary air valves, but the system was complex and was soon replaced with an external dashpot.
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