AVS vs AFB

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Brian Arcella

Brian Arcella

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The Poison Dart came with an AVS on a 340 intake manifold the engine appeared to run nice with the exception of a small miss nothing a tuneup couldn't fix, but the carb is really kind of scummy on the outside and they are generally a simple carb to rebuild, but I have several AFB's sitting around and 2 that are 600 cfm whihc will work fine on pretty much any small block.
So my question is whats your preference and why AVS or AFB?

Thanks again your input is always appreciated
 
Both good carbs. The AVS has a adjustable secondary valve for tuning.
 
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toolmanmike said:
Both good carbs. The AVS has a adjustable secondary valve for tuning.
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Now this was back in 1976, I was running a stock 69 440 Charger that had the AVS.Can't remember what the size is factory. Let's say 625 CFM. Got a Carter AFB with the same size throttle plates and bolted it on.Ran the car and it ran within 100th.Granted to say they are damn close to being the same.
 
Id go with the AVS. The AFB's were dialed in to the motors/cars they were installed on. IIRC there were over 5000 AFB OEM part numbers with all their jets, bleeds, venturi pod and rod combos. The AVS it the same carb with the secondary adjustable spring door to dial it in further to your specific app. ie. the AFB required you to remove weight from the secondary door by grinding it off the counterbalance if you need the secondaries to come in earlier.
 
The AVS is the improved model. It's a somewhat better carburetor.
 
I like the AVS better because the adjustable secondary air door and the small bump in cfm due to the secondary side spray bars. If you have a 3 step rod
(which rod you new guys is easily identifiable by the raised rod cover. It looks a little like a hat rather than a flat top round on the edelbrock crabs.)
Swapping to a two step rod is easy and readably accepted with the flat top cover.

While an3 step rod is a fine tuned rod for the application it was one, you may get lucky to have it work well for you.

According to the old Carter tech line, they said to me that the small unit flowed 630 cfm. That’s 30 more than the same size primary AFB.
Then if your handy with a dremal, you could pick up a few more cfm.

Do not that you can convert an AVS to work with an electric choke. I used stock AFB parts. The Edelbrock should work. I don’t remember all the in’s and out’s. But I never had trouble making the swap. The worst thing you don’t have is a drill bit and tap to match the screw set to Mount the electric choke. It is a very easy job to perform.
 
rumblefish360 said:
I like the AVS better because the adjustable secondary air door and the small bump in cfm due to the secondary side spray bars. If you have a 3 step rod
(which rod you new guys is easily identifiable by the raised rod cover. It looks a little like a hat rather than a flat top round on the edelbrock crabs.)
Swapping to a two step rod is easy and readably accepted with the flat top cover.

While an3 step rod is a fine tuned rod for the application it was one, you may get lucky to have it work well for you.

According to the old Carter tech line, they said to me that the small unit flowed 630 cfm. That’s 30 more than the same size primary AFB.
Then if your handy with a dremal, you could pick up a few more cfm.

Do not that you can convert an AVS to work with an electric choke. I used stock AFB parts. The Edelbrock should work. I don’t remember all the in’s and out’s. But I never had trouble making the swap. The worst thing you don’t have is a drill bit and tap to match the screw set to Mount the electric choke. It is a very easy job to perform.
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If you change from 3 step rods to 2 step you also need to change the jet to the AFB style jet. If memory serves me correctly the jet is taller.
 
I am very happy with my newer 800 AVS over the 750 DP Holley!

It was very easy to tune for idle and cruise!
 
mcodecuda said:
If you change from 3 step rods to 2 step you also need to change the jet to the AFB style jet. If memory serves me correctly the jet is taller.
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Yes sir! That would be correct. I’ll have to dig out my old AVS jets and compare. It’s a small difference IIRC.
AJ/FormS said:
You can put the AVS on anything and with a few adjustments, it will run like a champ.
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Dang straight!
 
AVS,,,,,I like original and enjoy keeping my confidence in the great Chrysler Corp. design engineers of days gone by.
 
a little correction is needed it is actually an Edelbrock performer not an original AFB but close enough I did a little experiment the other day with soda blasting and both carbs cleaned up real nice now to drop them in the Berryman carb cleaning bucket I am leaning towards the AVS but will rebuild both
 
I've never understood why Carter--then later Ed---reproduced an AFB instead of an AVS
 
Carter DID reproduce the AVS. They are in my 77-78 Carter catalog. Model #s 6433-6437.
Edel reproduced the AVS & added venturiis to the secondaries, which in my opinion, was an improvement over the original AVS.
 
If you are going to tune and tinker AVS. For a full built, all out race carb? AFB might be easier to Frankenstein. I have heard of NSS stick shift guys removing the counter weight butterflies all together. They launch at such rpm you don’t need secondary enrichment for the secondaries. Like a double pumper without the second pump. I’m pulling enough air through my 800 AVS I can’t slow the door down enough, you can only crank on the little spring so much until it breaks.
 
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