AFB vs AVS for Hemi

Posted By: mopartony

AFB vs AVS for Hemi - 06/11/13 02:58 PM

Guys I have a friend who is need of this info.

What are the pros and cons for running the AFB's or the AVS's.

Which are the best to run?

This is a very warm 496cid Hemi. It will have an inline 2x4.

Holley�s are a no go end of story.

All info is appreciated and good AFB and AVS carb builders is welcome too.

Posted By: sixpackgut

Re: AFB vs AVS for Hemi - 06/11/13 03:04 PM

AFB has weights that control the secondary opening

AVS has a spring loaded flap like a quadrajet or thermoquad

I prefer the AVS carbs and that is what I run on my car

Posted By: polyspheric

Re: AFB vs AVS for Hemi - 06/11/13 03:11 PM

IMHO the AVS secondaries are both easier to adjust and to match F vs. R.
There's more tuning commentary for the AFB.

Posted By: Performance Only

Re: AFB vs AVS for Hemi - 06/11/13 04:48 PM

I've built quite a few Hemi's with the inline 4 and the AFB carbs have always worked like a charm. Maybe it has something to do with the design of the intake?

Posted By: RUNCHARGER

Re: AFB vs AVS for Hemi - 06/11/13 05:18 PM

AVS's on a Stage V inline are the preferred street setup if originality isn't a concern. Either will work fine but I like the adjustable flap of the AVS. My current car is a 472 with a stock Hemi Convertor and 3.23 gears and it runs the best with stock rejetted AFB's and their progressive linkage however.
But if your friend has a bit of gear and some convertor the AVS's on the Stage V will work great.

Sheldon

Posted By: domingo

Re: AFB vs AVS for Hemi - 06/11/13 05:52 PM

dual avs 800s are said to work great on a stage V dual carb intake...

dual AFBs is what came on from the factory.....so I guess that would be the choice if you are running a stock intake??? The fast guys use a stock vanke ported intake also use AFBs

Posted By: torkrules

Re: AFB vs AVS for Hemi - 06/11/13 06:13 PM

Quote:

AFB has weights that control the secondary opening

AVS has a spring loaded flap like a quadrajet or thermoquad

I prefer the AVS carbs and that is what I run on my car

Posted By: dogdays

Re: AFB vs AVS for Hemi - 06/11/13 06:15 PM

AFB, AVS, really quite similar. The AVS has a tunable air valve secondary, the AFB is an earlier version and doesn't. So if you want to tune secondary opening on an AFB it's more work.

I'd say two Edelbrock Thunder series or two of the new Street Demon with the black plastic float bowls.

R.

Posted By: kissmyaspen

Re: AFB vs AVS for Hemi - 06/11/13 06:28 PM

Is this for a NSS set-up? if so I would give these guys a call Diamondback

Posted By: Cab_Burge

Re: AFB vs AVS for Hemi - 06/11/13 06:35 PM

All the stock street Hemi intake manifolds came with the AFB bolt patterns, the AVS are the same bolt pattern as the 4150 Holleys. You can drill the base of the AVS to change them to fit the AFB manifolds and pattern

Large motors, especially 426 type Hemiroids, like lots of air

Posted By: BB65Barracuda

Re: AFB vs AVS for Hemi - 06/11/13 06:42 PM

I use AFB'S on mine

Posted By: mopartony

Re: AFB vs AVS for Hemi - 06/11/13 08:36 PM

Thanks guys.

What about tuning parts? are those available?

This car has full exhaust and is strictly street use. No track time to speak of.

Go out drive and have fun, lots of fun but fun none the less.

Posted By: Triggerfish

Re: AFB vs AVS for Hemi - 06/12/13 05:39 AM

I had two 600 Eddy AFB's on my 434 hemi (Stage 5 intake) & after switching my cam to a solid Bullet, I switched to 650 Thunders, which were easier to tune & gave excellent throttle response. Both bolted right onto the Stage 5 intake & fit the Shaker baseplate. Hard to judge if the 650's outperformed the AFB's since I changed the cam & rebuilt the Hemi, but the Thunders sure had great response.

Posted By: dvw

Re: AFB vs AVS for Hemi - 06/12/13 11:35 AM

I run two stock 750 eddy AFBs on my 572 wedge. Chokes removed and secondarys jetted up, no other mods. Even with a 285@.050 cam it idles great, good throttle response. Its gone 9.30@144 .
Doug

Posted By: Moparmal

Re: AFB vs AVS for Hemi - 06/12/13 11:45 AM

Quote:

Quote:

AFB has weights that control the secondary opening

AVS has a spring loaded flap like a quadrajet or thermoquad

I prefer the AVS carbs and that is what I run on my car

X2