Edelbrock AFB vs AVS

[Jay_340]

Anyone have much experience with these two carbs? Was thinking that the Holley DP is a bit too much for the street and might swap over to one of the Edelbrocks. The "Thunder" AVS is $70-80 more than the AFB, but is the performance THAT much better? Would one of the Holley Street Avengers be better?

 

[RustyRatRod]

I would not call the AVS performance better. It is noticeably smoother, though. That was the whole point with the AVS. It was an improvement over the AFB in drivability. The performance however is about the same.

That said, I have an Edelbrock 626 AFB on my truck and I cannot see how it can be much smoother or better. It runs fantastic. I am very happy with it.

 

[cudajames]

Here is a great write up from on own Triple R

The 1400 series is bases on the Carter AFB. They were decent carburetors. But the Carter AVS was a big step up in improvement over the AFB.

The 1800 series is based on the Carter AVS. They are considered superior to the AFB for several reasons but the number one reason is the smoothness of the transition into the secondary side of the carburetor.

The reason for this is unlike the AFB style carburetor, the secondary boosters are located under the secondary air door instead of on top of it. This allows for a much more accurate air signal to the boosters and results in a much more smooth operation of the secondary side.

Also another great benefit is the AVS style carburetors, much like the Thermoquad, are a vacuum secondary design. This means that they are much more forgiving in an over carbureted situation and that one size carburetor will work on a variety of engine sizes.

Since the AVS style carburetors will only flow what the engine demands, that means they will never "over carburete" the engine. Rich primary conditions can easily be adjusted out, since they have an almost infinite adjustability with springs, metering rods and jets.

IMO they are probably the dead best carburetors out there for a street or street/strip car. Repair parts are cheap and plentiful. It's not like trying to find a needle in a haystack tuning kit for a Thermoquad, because all kind of tuning kits are available.

IMO, the 1800 AVS Thunder carburetors leave the 1400 series in the dust. That's my story and I'm stickin to it.

 

[rumblefish360]

The AFB's one draw back is when you hammer it early, the weighted secondary velocity door slams open with not enough pump shot to cover it.
The AVS's spring loaded door provides tention to the door to slow the opening on low speed W.O.T. Hits.

Many have complained about the Street Avangers bog. It is a constant complaint that is t always worked out by the owners to the point some carb shops offer a "Fix" for it.

If your not going to go through the pains of tuning up a Holley DP for the street, choose the AVS. I'd look to Edelbrock for a new version, a cross hybred of the old AVS & AFB because an older AVS is a little harder to find being there very old now. There secondary fuel delivery is a spray bar (brass tube) with holes in it. Very good for air flow. Fuel is atomized across the rear bores. The Edel. Version still has boosters which atomize in the center of the bore like all other carbs. (Except the TQ)

 

[RustyRatRod]

Having this Edelbrock now, I am not sure if I will ever go back to a Holley. It seemed in the past that Holleys I had ran different every day. This Edelbrock is stone consistent.

 

[RustyRatRod]

Thanks. I had remembered writing that, but I was too lazy to find it.

Here is a great write up from on own Triple R

The 1400 series is bases on the Carter AFB. They were decent carburetors. But the Carter AVS was a big step up in improvement over the AFB.

The 1800 series is based on the Carter AVS. They are considered superior to the AFB for several reasons but the number one reason is the smoothness of the transition into the secondary side of the carburetor.

The reason for this is unlike the AFB style carburetor, the secondary boosters are located under the secondary air door instead of on top of it. This allows for a much more accurate air signal to the boosters and results in a much more smooth operation of the secondary side.

Also another great benefit is the AVS style carburetors, much like the Thermoquad, are a vacuum secondary design. This means that they are much more forgiving in an over carbureted situation and that one size carburetor will work on a variety of engine sizes.

Since the AVS style carburetors will only flow what the engine demands, that means they will never "over carburete" the engine. Rich primary conditions can easily be adjusted out, since they have an almost infinite adjustability with springs, metering rods and jets.

IMO they are probably the dead best carburetors out there for a street or street/strip car. Repair parts are cheap and plentiful. It's not like trying to find a needle in a haystack tuning kit for a Thermoquad, because all kind of tuning kits are available.

IMO, the 1800 AVS Thunder carburetors leave the 1400 series in the dust. That's my story and I'm stickin to it.

 

[Jay_340]

The AFB's one draw back is when you hammer it early, the weighted secondary velocity door slams open with not enough pump shot to cover it.
The AVS's spring loaded door provides tention to the door to slow the opening on low speed W.O.T. Hits.

Many have complained about the Street Avangers bog. It is a constant complaint that is t always worked out by the owners to the point some carb shops offer a "Fix" for it.

If your not going to go through the pains of tuning up a Holley DP for the street, choose the AVS. I'd look to Edelbrock for a new version, a cross hybred of the old AVS & AFB because an older AVS is a little harder to find being there very old now. There secondary fuel delivery is a spray bar (brass tube) with holes in it. Very good for air flow. Fuel is atomized across the rear bores. The Edel. Version still has boosters which atomize in the center of the bore like all other carbs. (Except the TQ)

Hmm. Avenger Bog. I have not heard that, but thanks for the tip.

With this engine, I have tried the AFB and the DP. The AFB seemed to have more snap when you hit the throttle, but the DP has a stronger WOT pull. When I took the AFB apart, I noticed that some of the internals weren't just a bit dirty or gummy.....they were corroded. (New England woes by the beach) I have heard of guys n gals getting the DPs to run well for the street, but I still think it may still just be a wee bit much if I'm not going to be racing it all the time. I might hit the track once or twice a year, and that's it. So that's why I was thinking of going back to a Carter-brock.

I think I'll start looking more into the AVS carbs. Thanks again guys!

 

[rumblefish360]

"New England by the water woes."
Tell me about it. Long Islander here. Never more than 12 miles from salt water.

The DP is how large?
I like a snappy throttle myself on a street car. Being that (*I think*) the Edelbrock is smaller, the velocity is higher giving you that instant throttle response. This should also give you an edge on mileage. I would suggest the AVS model if you need to replace the current carb.

 

[Jay_340]

"New England by the water woes."
Tell me about it. Long Islander here. Never more than 12 miles from salt water.

The DP is how large?
I like a snappy throttle myself on a street car. Being that (*I think*) the Edelbrock is smaller, the velocity is higher giving you that instant throttle response. This should also give you an edge on mileage. I would suggest the AVS model if you need to replace the current carb.

The DP is a 650, stock, 68/72 jets. The old AFB I had was a 600, the 1406 model IIRC. In all honesty, I could probably do a super tune on the DP and live with it, but I think that a super tune on an AVS would get me superior performance on all aspects.

So, here's what I got:

360 .020 over, Roughly 10:1 CR
Lunati Voodoo cam 268*/276* @ .494/.513 total lift
Edelbrock Perf. RPM intake
2.02/1.60 heads (I think they are J heads) with some mild work (gasket matching, bowl work, smoothing on the short side radius)
Still working on timing, but so far it's 32* total, 12* initial
Stock '71 Exhaust manifolds into 2 1/4" exhaust
4-speed/3.91 gears
Stock body, interior, etc.