The Stovebolt Site Forums The Shop Area Engine Shop Old carter AFB dies, ordered a new perfomer

Well, the old afb on my 66 vintage 327 is leaking around the throttle shaft bushings, dumping raw gas on the manifold, hard starting, and vaccum leaks. How do youall like your performers?

The Performer is good. It is almost an exact replacement for the AFB. They must have sold millions of them. Every show you go to practically every car has one on it.
I,d be interested in buying the old one.
[email protected]

64,
You may need a insulator plate under the new carb that the old one did not have. Edelbrock carbs tend to have a hot start problem without it. The last one I installed had a disclaimer in the box about flooding and fuel pump pressure.
Fred

Thanks, i think i have one hanging on the wall. Thats one of the problems i am trying to eliminate. I have 2 afbs, one from a 65 impala 300hp. 327, the other one, (the one i am running) from a 66 impala 300 hp. 327.

Blu 64 - the original Carter on a 1966 would have been an AVS not an AFB. The AVS were somewhat problamatic. The earlier AFB's used by Chevrolet on the small blocks were virtually "bullet-proof" except in the area of the idle mixture control screw, where "heavy handed" "mechanics" could break the seat by overtightening the idle mixture control screw.

In terms of both value (dollars) and performance, a worn-out genuine original small block AFB is worth 3 to 4 brand new clones. Even the SR Carter's (same number, service date) are worth more than the clones.

Check the numbers on the units you have. I would suggest you will be far more pleased with a working original than with the clone, and for a much longer period of time.

The good numbers are:

3720s for auto transmission vehicle
3721s for manual transmission vehicle

Jon.

Jon, or anyone else, can you direct me to a listing of the CFM for the old Comp. Series AFB's? I have a couple with numbers in the 47XX range. I've run across some partial listings of the later 9XXX series but never for these older ones. Thanks, Doug

Carter (NOT clones) aftermarket carb CFM ratings:

Race:

4758s manual choke 500 CFM
4759s manual choke 625 CFM
4760s manual choke 750 CFM
4761s no choke 500 CFM
4762s no choke 750 CFM
4846s or sa manual choke 850 CFM (TQ)
4847s or sa manual choke 1000 CFM race (TQ)

Street:

9400s 400 CFM GM linkage elec choke
9410s 400 CFM GM linkage elec choke EGR provision
9500s 500 CFM GM linkage elec choke
9501s 500 CFM Chrysler linkage elec choke
9510s 500 CFM GM linkage elec choke EGR provision
9511s 400 CFM Chrysler linkage elec choke EGR provision
9525s 625 CFM GM linkage elec choke
9626s 625 CFM Chrysler linkage elec choke
9627s 625 CFM Ford linkage
9635s (NOT sa) 625 CFM GM linkage elec choke EGR provision
9636s (NOT sa) 625 CFM Chrysler linkage elec choke EGR provision
9637s (NOT sa) 625 CFM Ford linkage elec choke EGR provision
9800s 800 CFM GM linkage elec choke (TQ)
9801s 800 CFM Chrysler linkage elec choke (TQ)
9810s 800 CFM GM linkage elec choke EGR provision (TQ)
9811s 800 CFM Chrysler linkage elec choke EGR provision (TQ)

sa (except 4846 and 4847) models are the beginning of the clones (when Federal Mogul accountants redesigned the AFB) as are other numbers (even if they say Carter on the carb, Federal Mogul sold "Carter" carbs after about 1985).

Jon.

These are "wet" ratings (more accurate than the "dry" rating of some competitors).

Thanks carb, i was confused on that, but have been told by many that it is an afb. I will take YOUR word for it! Would the 65 model be a avs? It always seemed to run better, but it has been 20 years since i have run that engine.

Blu - the 1965 would have been an AFB.

The AFB is quite easy to distinquish from the AVS

(A)luminum (F)our (B)arrel
(A)luminum (V)acuum (S)econdary

The AFB (except on a very few Chrysler O.E. carbs) has a weighted secondary valve. This valve is below the secondary boosters.

The AVS has a plate on top of the secondaries (looks like a second choke Plate) that is tensioned by a spring.

Also, if all else fails, either the letters "AFB" or "AVS" are cast in front on the passenger side.

Jon.

Jon, Thanks for all the great info. Much appreciated. Doug

Doug - my pleasure. I really like the OLDER AFB's and the TQ's.

I guess every company has to have their Rochester B. For Carter (my opinion, others may differ) it was the AVS.

Jon.

Not to argue with the expert, BUT AVS stands for Air Valve Secondary.
I have a '70 small primary on my 292 and a '69 383 small primary bagged on a shelf. They both have the "AVS" cast on the drivers side, rear.
I think the AVS is a great carb and the Air Valve spring allows you to adjust when YOU want the secondary to come in, by simply tightening/loosening the spring. The secondary boosters above the weighted secondary valve on the AFB caused a delay in fuel delivery. Carter moved the air valve above the fuel discharge and solved two problems.
I also have to say my Rochester B worked very well. It was just too small and looked funny on the Clifford intake.

Richard - go right ahead, and you are quite right on the Air Valve Secondary; I have been mistyping all night (I read a 94 to mean 64 on another board). You are also quite right on the secondary boosters on the original design of the AFB in 1957; but this issue was solved early in the development of the AFB by the tertiary secondary circuits.

However, if the AVS works well for you, you would be one of a few (hey, that makes them cheaper to buy!).

You are correct that the air valve spring may be adjusted, but all of the Carter tests showed that the airvalve worked best at the factory setting. With the AFB, one could change the air valve (there are many different ones available), and the weighted airvalve had two variables (weight and angle). Granted, most tuners do not have the inventory of these that I do. Generally the small block Chevy engines like airvalves with large angles; high torque, low RPM engines like airvalves with small angles. Using both weights and angles, one has better control of both the beginning of the valve opening, and the rate of opening.

Carter did offer some aftermarket AVS carbs during the Chrysler AVS years (1968-1971), but these are so rare, I have NEVER even seen one. The AVS was basically a smog carburetor that was a stop-gap measure leading to the much improved TQ. Again, the TQ works best when the air valve is adjusted to the factory setting.

I will admit that some of the Chrysler racers have been reasonably successful with the AVS by removing the metering rods and rejetting the primary accordingly (ala Holley). This works reasonably well for WOT, but leaves much to be desired for street operation.

And some additonal information on the AVS: of the Chrysler models, the small primary version was rated 630 CFM, and the large primary 750 CFM.

And your success simply proves there is no single correct answer.

Jon.

I always liked my avs.A mechanic friend who was(he's passed on ) much better with carbs than me, set mine up for me when i was running a standard. The secondaries opened kinda late,giving time to build vaccum and made my 327 seem much bigger than it was.(My theroy) I now have the performer on the truck and taken for a test drive. Seems to have a little flat spot, but i can probably tune it out. Carb King, what do you suggest, timed vac, or manifold vac for my dist. advance. I have always run timed.

I came home with an AVS 4 Bbl Carter after a show wrapped. (It had been a prop in a gas station scene.} I don't have the carb handy now, but it was an AVS. It has a purple leather cup in the accelerator pump piston position. Some one had monkeyed with it, as it had the primary jets in the opposite place as the secondary jets. Also I read AVS metering rods had 3 steps instead of 2 steps on the AFB metering rods -- the mid range supposed to fill the gap for midrange power. I Don't know of a source for 3 step rods for Carters. A query to the Tech Dept of Edelbrock was less than productive. So I was unable to find the cfm and match it to a clone rebuild kit. I'll dig out the carb numbers and jet and rod sizes later.

Blu - sorry, no advice on clones. Best advice I can give you is put the 1965 carb on the engine.

BT - you have found another of the AVS short-comings. The third step on the metering rod was actually a smog-emission step, and was necessary as the AVS has an extra circuit in the primary boosters. Carter made virtually no selection of rods for the AVS (memory says four), as almost no one wanted to try to use them for performance.

The primary jets were unique also (called the "high-step jet") as Carter wanted to eliminate confusion from the 2 and 3 step rods, which are not interchangeable.

The AVS had its own "strip-kit". We thought we wanted to reproduce the AVS strip kit several years ago, but advertising for 2 years in HMN generated less than 10 responses. A friend at Carter told me he was not surprised, as when Carter still had the AVS kit, they sold more than 100 AFB kits to 1 AVS kit.

Jon.

Well, I'll reprint my email to Edelbrock Tech Dept:
"Gentlemen:
I have a Carter AVS carb which I'm trying to build up for a future project: '67 Chevy K/10 [half ton 4 x 4] Suburban with a 454 engine.
I understand Edelbrock now is marketing an AVS carburetor.
This carb is stamped K7 4966S. Inside, the metering rods are stamped 16-189, primary jets are 120-389, secondary are simply "489." [I think someone may have reversed the jets from their proper positions -- as the 489 jets are old Carter "high-types" to go with the 3-step metering rods that were peculiar to the Carter AVS system. Also the accelerator pump piston is brass with a purple (!) leather cup unlike the EDL 1470 nylon/rubber unit in the [AFB] Performer series. The pump piston spring is red, also. The step-up springs are plain but appear most like the purple springs from my AFB spring kit. This carb has a vacuum choke and a passenger-side EGR port (which I intend to delete. And I also intend to convert to manual choke.) It also has a hot idle compensator bi-metal vacuum leak inducer between the secondary venturies -- which I will also delete.
I measured the throttle bores with a vernier caliper: Primaries: 1.433~" Secondaries: 1.678~".
My questions are:
1] What Edelbrock Thunder carb is this closest to, so I can get a calibration kit for it?
2] What is the CFM?
3] Does Edelbrock make the 3-step metering rods and "High-type" jets for the AVS Carb system, or do I have to convert to the AFB system 2-step metering rods? ..."

Their answer:
"1) We have no way of knowing which AFB carburetor is closest to our carburetor. Their jets and rods went by a different numbering system than ours, which go by orifice size.
2) We do not have informantion on Carter carburetors.
3) we do not make a 3-step metering rod, only 2-step. Thanks. ..."

So I figured I lost his interest as soon as he realized I wasn't buying one of their shiny new spendy carbs. Also he wasn't paying attention since I was asking about the AVS carb not the AFB. Clearly "AFB" is a bad word in their Company vocabulary. "Performer" is the good word.
To us old hotrodders one aluminum four barrel is pretty much like another on paper. But aparently appearances can be deceiving.

I read Dave Emanuel's book, "Super Tuning and Modifying Carter Caburetors," and thought I saw something in there about how the 3-step rod was a good idea for mid-range performance -- like in towing.
Since I intend to build my 454 to tow a 20' camp trailer, this seemed like a good idea. Finding someone with the technical chops to machine a custom pair of 3-step rods will be the difficult part.
Sorry for the long rant.
Can you, Carb King, answer my first and second questions?
Thanks.

BT - to your questions:

(1) Don't know, we will NOT use the clones, so no answers for clones.
(2) Carter published 630 CFM

A lot of years ago, my Dad purchased a 26' Winnebago with a 454. Trying to keep a long story short here. We went to the Fall Hershey swap meet annually, and would set the speed control at the speed limit. The time to Hershey from Eldon, Missouri AS THE 454 CAME FROM THE FACTORY was 20 hours.

The power, and especially torque, with the spread-bore carb was not what I wanted.

I then acquired and Offenhauser intake for a square-bore carb; and 2 Carter AFB carbs, a 4760s (750 CFM) and a 9625s. I then "married" the 2 carbs. Used the 4760s as the base carb, and grafted on the automatic choke, choke linkage, and fast idle circuit from the 9625s. Calibration was left as stock on the 4760s. I also built and installed a cold air induction system (air is pretty warm under that doghouse).

That fall, we again made the pilgramage to Hershey, and again set the speed control at the speed limit. This year, and subsequent years, the time was 18 hours!!! The difference - speed we were able to obtain in the hills of Ohio and Pennsylvania. And the interesting statistic - fuel economy was IMPROVED by 8 percent.

Jon.

Carbking, I am surprised and I guess delighted that you like the ThermoQuad. I have never had one or worked on one, but I had always thought they should be a good carb. Back in the day when they were still around it seemed as though no one had anything good to say about them. Everyone claimed the plastic section warped and then they were junk.
I have to wonder if the AVS carbs that you don't like had the two idle mixture screws or were they the ones with the single air-bleed screw in the middle? All of mine including a parts carb and a large primary 440 carb that I used to have, had the two mixture screws. As far as I know the '68 mopar and a few '69 used the single air-bleed that was located directly above the large vacuum outlet, bottom center front. I recall trying to help someone tune one of those up and we never could get it to run as smooth as you would like.
I have a 1968 HotRod magazine around somewhere that shows how they thought a '68 roadrunner should be tuned up. They said to turn the screw all the way in, which is counterclockwise because it has left hand threads. By they, I'm not sure if it was saying **** Landy did it for them or was just advising them to. You did mention about the screw or screws being turned all the way in.
Bt, your question about the two and three step rods is mentioned on this web site. I was looking around for more info on the different types of idle circuits and found it.

http://www.moparmusclemagazine.com/howto/155_0305_carter_avs_carburetor_install/pictures.html

They just used the flat AFB rod covers and the AFB rods and jets.

?You can't say a guys name? How about "Richard" Landy? I guess you can't say, "Dandy ****" either?

Bt, earlier you said, "a passenger-side EGR port (which I intend to delete."
That's not an EGR port. On '69 and earlier the air-vent or bowl-vent, what ever you want to call it was on the outside, behind the pump rod and connected to the pump linkage. In '70, they moved it inside and on the choke side of the carb. that "port" would have been connected to the charcoal canister to absorb all the evaporated fuel. I cut the cone section out of a carb filter so that it is a tight fit in the tube. It lets it breath and keeps the dirt out. I can never remember what these filters are called. I always call them stone filters. [img]http://www.zip-products.com/Zip/assets/product_images/CZ-1012.JPG[/img]

It's a "moraine" filter. Usually inside the carb. Often made of sintered brass.
For fuel filters, I use a big GF-15 Fram (paper element) inline with the fuel feed. I replace them every 10,000 miles.
I have a print out of that Mopar Muscle mag article.
From what CarbKing says I'm less enthusiastic about the AVS rebuild. I may just get a new 750 cfm Performer. Before the '67 Sub went down I had a Carter AFB 9635s on it. I got 6~8 mpg. I could also rebuild the 9635s too. It wasn't burned in the air-cleaner fire. I believe [for logistics purposes] it's closest to the EDL-1400 Performer.
Oh yeah, It was a Rochester Monojet that wouldn't line up, that got me started on putting a 4160 Holley 390 cfm on an Offy intake and Clifford headers on my 292 in a '68 C/10 stepside. That was back in 1978. I still have the truck, I'm on my 2nd rebuilt but the headers and intake came back up after a good hot tanking and bead blasting.