[SRR]

Back before I knew better we put a Edelbrock AFB on my son's 70 400 SBC Chevelle. It had a bog going into the secondaries every time. Apparently you cannot adjust the secondaries. We ended up with a Holley 3310 and the car ran like stink after that.

I've never used one but I heard the Edelbrock AVS is a decent carb. with more adjustable features.

[Sirrotica]

The Carter AFBs had weighted secondary air valves which were selected according to applications. I've never done it myself, but have read if you want to slow the air valve opening rate down you can drill holes in the weights and press led shot into them, similar to using mallory metal to balance an engine.

The one size fits all applications of E carbs is more than likely why there is transition bog on some applications. They seem to do the same thing as holley does, and err on the rich side to cover some of the metering shortcomings.

For as much as a new carb is, and how FITech and other companies have gotten the price down on fuel injection units, they keep getting closer in price.

[pastry_chef]

Originally Posted by 77 TRASHCAN

Secondaries come in at same rate, whether it's a 454 or a 283. Weighted arm controls rate

The OP noted Edelbrock 1806 has an adjustable secondary air valve.

[HWYSTR455]

I don't think the secondaries are adjustable on any of them, but could be wrong:

https://www.edelbrock.com/pub/media/...ers-manual.pdf

I remember back in the AFB days, you muck with the weights and you are going in the wrong direction, you can get lost. The objective is to manage vacuum during the throttle opening range. That can be done with tuning the primaries and secondaries with jets, rods, etc. If it's too fat, vacuum drops off, too lean, and vacuum is higher. Have to find the balance, or that's how I remember it.

I can't remember if there are different plunger springs, but I don't think so. I do remember some folks trimming them or stretching them out/shimming pocket, to fine tune. That too, you can get lost.

The biggest reason I went away from the AFBs is due to the side bowls, high G turns it could flood. Holleys generally could have flood issues on hard acceleration/braking. In my case, it was easier to deal with the acceleration/braking thing. So I switched. But I had a 2x4 AFB setup working very well. (on an Offy dual plane 360)

Original/old body castings can become porous, and actually seep through the body. Late in production, Carter, who may have actually been already bought out once, offered coated bodies, black, called Black Stallions. I at one point upgraded to those, and many of the porosity issues I had were resolved.

.

[pastry_chef]

Originally Posted by HWYSTR455

I don't think the secondaries are adjustable on any of them, but could be wrong:

https://www.edelbrock.com/pub/media/...ers-manual.pdf

That manual is for the original (old) series.

Here is the AVS Thunder Series.
Page 6 has the secondary details.
https://edeinstall.wpengine.com/wp-c...Carburetor.pdf

Seems they have a newer AVS2 series.
https://www.edelbrock.com/avs2-800-c...gine-1912.html

Might have a different version of secondary tuning --- "Additionally, the unique Qwik-Tune Secondary Air Valve allows for limitless calibration of the secondary circuit. Adjustments can be with simple hand tools in seconds to suit your application."

[HWYSTR455]

Another thing to note is that Carter, and believe Edelbrock, rate their' carbs' CFM differently than Holley, at a different mercury, and the same CFM rating by Holley on a AFB would result in too large of a carb. (AFBs having smaller numbers for rating that Holleys for same flow)

That can throw your sizing off, and, hence, your secondary opening rate.

Looks like Edlebrock may also offer the black ones.

.

[HWYSTR455]

Originally Posted by pastry_chef

That manual is for the original (old) series.

Here is the AVS Thunder Series.
Page 6 has the secondary details.
https://edeinstall.wpengine.com/wp-c...Carburetor.pdf

Innnnteresting! Ok, yeah, adjusts the spring preload.

.

[carbking]

Originally Posted by HWYSTR455

I don't think the secondaries are adjustable on any of them, but could be wrong:

https://www.edelbrock.com/pub/media/...ers-manual.pdf

I remember back in the AFB days, you muck with the weights and you are going in the wrong direction, you can get lost. The objective is to manage vacuum during the throttle opening range. That can be done with tuning the primaries and secondaries with jets, rods, etc. If it's too fat, vacuum drops off, too lean, and vacuum is higher. Have to find the balance, or that's how I remember it.

I can't remember if there are different plunger springs, but I don't think so. I do remember some folks trimming them or stretching them out/shimming pocket, to fine tune. That too, you can get lost.

The biggest reason I went away from the AFBs is due to the side bowls, high G turns it could flood. Holleys generally could have flood issues on hard acceleration/braking. In my case, it was easier to deal with the acceleration/braking thing. So I switched. But I had a 2x4 AFB setup working very well. (on an Offy dual plane 360)

Original/old body castings can become porous, and actually seep through the body. Late in production, Carter, who may have actually been already bought out once, offered coated bodies, black, called Black Stallions. I at one point upgraded to those, and many of the porosity issues I had were resolved.

.

The genuine Carter AFB carburetors are infinitely adjustable.

Since I banned the imitations from my shop after the first experience with the quality, I can honestly say I do not know (nor do I care) what tuning pieces are available for the imitations.

Jon

[HWYSTR455]

Thank you Jon, and after I posted, I went back and looked, and Carter did in fact offer a metering rod spring kit that included 3, and some 5 sets of diff springs. I think the springs were also offered individually, but my memory is failing me on that.

I believe I even spoke to you several times in the late 80s & early 90s regarding my 2x4 setup, but again, that was some time ago!


.

[SRR]

Originally Posted by pastry_chef

The OP noted Edelbrock 1806 has an adjustable secondary air valve.

I just assumed it was an AFB. The AVS is a good carb. it just sounds like poor quality control seems to be the root of most "shiney" parts.

[Cliff R]

Just take a look at the accl pump Edelbrock uses in them. It's soft plastic pressed into plastic, and the large end will bend nearly 45 degrees it's so loose on the shaft. The light blue pump seal is "soft" and swells up quickly/fails in contact with any concentration of ethanol. I have locals drag those things up here all the time wanting me to rebuild or put kits in them.

I direct them around toward the back of the shop, and tell them that the best sound that carb will ever make is when it "tinks" off the dumpster......FWIW.

The "Thunder Series" copied the AVS design so will have a spring loaded secondary air door in the airhorn. I tested the original Performer Series or AFB clones way back when I wrote the Q-jet book, wanting to test what was currently available dyno, street and track, etc. The AFB clones were HOPELESS on my set-up, and it would puke all over itself with any attempt to bring the secondaries in. The air door just dropped open and it went lean and no way to tune that out.

A few years later I obtained one of their Thunder Series AVS units and did some drag strip testing with it at a private track rental on two different cars we took with us that day. We carried along a couple of Holley carbs and half a dozen Q-jets as well. We were able to tune the AVS for good runs on both cars, but it also ran slower than all other carbs tested that day. It took a couple of hard launches to dial in the spring loaded air door then it really didn't do all that bad, but was down in both ET and MPH on both cars we took that day no matter how I adjusted it or what jets we tried using in it (I took along Edelbrocks expensive tuning kit). Overall I'd still say it was a decent carb, but one day with it certainly doesn't tell us how it will hold up in long term service, or how much fuel it will consume for "normal" driving, etc.......Cliff

[64 Poncho]

Had a 750 cfm Ecarb on a 68 400 that came on the car I bought it. Could never get it tuned. Different jets, rods, springs. It was an older version, but still wasn’t impressed. Found out when I rebuilt the engine, valves were not adjusted correctly. After market cam with adjustment ran down to the bottle neck on stock Pontiac Studs.
Took all the play out of the plungers and actually cracked the seats in the lifter. Well its all better now and I put a Q jet with a factory
Intake manifold. The best part is I traded the carb for a good running Stihl 028 chainsaw! Even up!!

[00fxd]

It's pretty simple. If you want it to run nice and predictable like your moms station wagon you use an AFB/Clone [or if applicable the original Qjet]. If ya wanna go fast you use a Holley.

[Sirrotica]

So in essence what you're saying is, if you want your car to run terrible, and unpredictably, idle badly, get poor fuel mileage, but go really fast at one throttle position, (WOT), you buy a holley?

I'd kind of tend to agree, only thing is most E carbs clones don't come close to real Carter AFBs performance. Most street cars (this is the street section) need to operate well at all speeds. And my race cars have all used reworked Q Jets, so you can go fast with them also. Other than that I agree 100%..........

The statement is akin this one, "If you want a Pontiac to run, put a chevy in it". Never bought into that one either......

See quote #1 on my Pontiaddict shirt I designed, and sold, for many years:

[PontiacJim1959]

For dual quad applications, I prefer the AFB. Never liked nor tinkered with Holley's but had at one time owned a pair of modified 660CFM center squirters that I had on a 440 Weiand Tunnel Ram that was going to be modified to fit on my stroked 482CI 409 engine. That's the only Holley I had and never got to run them as I wound up selling the engine and parts.

Setting up my Warrior tunnel ram, I have gone with the AVS2 which offers an annular booster ring in the primaries and the adjustable air valve, like a Q-jet, on the secondaries. If it doesn't work as well as I hope, then I will go with a pair of older AFB's - would really like to use a pair of Q-jets. The quality of the AVS2 looks pretty good to me and the adjustability is fairly straight forward and easy just like the AFB's.

[tom s]

The best I have found for 2-4 tunnel rams is REAL Pontiac SD AFBs.Next would be Buick and 3012 Chevys for smaller CI and 3705 Max wedge for larger CI.I run the 750s on my 421s.The 3705s have to be rejeted as they have staggered jetting for the Xram intakes.The real factorys are very pricey compared to the others.61-63 on this site can set up a pair of AFBs.Tom

[Mike Davis]

Originally Posted by 00fxd

It's pretty simple. If you want it to run nice and predictable like your moms station wagon you use an AFB/Clone [or if applicable the original Qjet]. If ya wanna go fast you use a Holley.

Are you sure about that? I have been faster with AFB's than a Holley.

[00fxd]

Originally Posted by Sirrotica

So in essence what you're saying is, if you want your car to run terrible, and unpredictably, idle badly, get poor fuel mileage, but go really fast at one throttle position, (WOT), you buy a holley?

I'd kind of tend to agree, only thing is most E carbs clones don't come close to real Carter AFBs performance. Most street cars (this is the street section) need to operate well at all speeds. And my race cars have all used reworked Q Jets, so you can go fast with them also. Other than that I agree 100%..........

The statement is akin this one, "If you want a Pontiac to run, put a chevy in it". Never bought into that one either......

See quote #1 on my Pontiaddict shirt I designed, and sold, for many years:

Well not really but sorta. As you likley know they are different than the station wagon carb. The Holley will idle a bit richer etc [but even that can be tuned out] but the throttle responce will be more noticable. The larger pump shot will cost a bit of fuel mileage, and all things being equal the Holley will be worth a length in the 1/4. Everything is a trade off.

[00fxd]

Originally Posted by Mike Davis

Are you sure about that? I have been faster with AFB's than a Holley.

Pretty sure. There are exceptions to every rule. But I always have great respect for guys that take the the time to make Qjets and AFB's and thier clones go fast. But I stand by my opinion. The sucessesful marketing by Edlebrock dissapointed me from the start. I bought into it years ago when they first brought out that "Compitition Series" trusting Edelbrocks good name for hot rod parts - soon saw the light. Bolt on an 1850 in place and feel the difference.

[Sirrotica]

Originally Posted by 00fxd

Well not really but sorta. As you likley know they are different than the station wagon carb. The Holley will idle a bit richer etc [but even that can be tuned out] but the throttle responce will be more noticable. The larger pump shot will cost a bit of fuel mileage, and all things being equal the Holley will be worth a length in the 1/4. Everything is a trade off.

FWIW, every dirt track car that I raced against, without exception, had a holley on it, so how is it I beat a whole bunch of chevys, fords, and mopars with a Q Jet, on a Pontiac, with dual radiators, a T400 transmission? No one else raced anything close to what I did, and just like clockwork, I beat them every week. If you can't think outside of the box, you're doomed to be in the box.

Just to clarify I have run holley carbs on street and race cars, but don't like their tendency to load up when idling. On a street car it has been my experience that you have to keep adjusting them because they don't seem to be able to hold adjustments, such as float level. Plus the tendency of the accelerator pumps to leak fuel onto the intake manifold if the diaphragm leaks, and the bowl gaskets, and bowl screw gaskets tend to dry out and leak fuel. Been plenty of engine fires attributed to holley fuel leaks.

You don't need a holley to win, you, like many others, have been brainwashed to believe you do. The engine does not know what name is on the side of the carb, and it could care less. As long as it gets the correct fuel mixture, at the correct time, it will perform just as well with whatever carb is on it.

One other thing, I never paid for any of my race car carburetor cores, just because of people that think the same way as you do. I was given a bunch of QJ carb cores because someone believed they were going to double their horsepower by switching to a high dollar aftermarket carburetor, and I got their scraps for free.

The cores must be modified for racing, or even high performance street use, it's called sweat equity. If your wallet isn't fat, you work harder to use what you have, and keep the difference.........