Been having some problems with the 4640SA Carter AVS on my 69 Charger. Its a very mild 440; six pack flat tops that sit .005" below the deck, 452 heads, K6401 Summit cam, stock 70 AVS intake manifold, TTI headers into 2.5" duals and an h-pipe, 3.23 sure grip. Since I put the carb on almost a year ago. It has been completely rebuilt, all passages blown out with 140psi of compressed air, HIC blocked off, new floats, etc. My problem with it is it doesnt seem to idle right. The mixture screws are almost 4 turns out, to the point I had to stretch out the springs on the screws to keep them tight. Any further in and it starts idling like garbage. It will literally burn your eyes standing behind it. I switched over to the two step Edelbrock rods and jets on the primary side. Im currently running 70/47 rods, and .113 jets...secondaries are .098s. After a drive, the plugs are a very dark brown. I need to lean out the cruise side and was going to try out some 73/47 rods. Distributor is at 14 initial, 35 total, all in by 2200rpm. I picked up a fresh Holley 3310 (750) from a friend of mine, and I have a perfect 6322s Thermoquad. Ive never been much of a Holley fan on the street, and always preferred Thermoquads. Im not a fan of squarebore/spreadbore adapter plates though.

I have been fighting this AVS for a while now, and am not a fan of spending $15 for a pair of rods, and over $10 for a pair of jets. A reason I have never been much of a Carter/Edelbrock fan. I have a complete Mopar Performance Holley jet kit with sizes ranging from 64 to 99. The Holley is tempting me, but dont like the idea of relocating the coil to put it on.

For a car like this that is cruised around on the weekends, run hard through the gears every time its driven, etc, which of the three carbs would be the best bet? The current AVS, the Holley, or the Thermoquad?

open up the idle jets .037" and the 4640 should purr.

That's another thing I was wondering about. I've never modified the internals of an AFB or AVS before. Which passages are the idle jets?

Holley

Not if the TQ is set up right !!

Awesome! So the tip of the idle fuel jet needs to be opened up a little bit? Do you recommend a good starting point?

the idle jet smog specs are .031" for an automatic trans. the 4spd cars were .035". i use .037" in my 4618s and it really smooths out the idle. most pre smog big block afb's were .035".

I'll have to give it a shot. .035" seems pretty big. I'll have to pull it apart, but it doesn't seem like the overall tube diameter is even .035"

first I would blast the clusters and the ports the idle mix screws are in with brake kleen. even tho it is rebuilt, something is way wrong with the carb (& that is a mild cam so not seeing how poor idle vacuum could be involved in this). lets get the carb squared away then fine tune the idle bleeds etc. do you have a "square" or close to it for the transfer slot?

That's what I figured. I've had the carb apart twice already, cleaned all of the passages out, blasted them with 130psi of compressed air. It's pulling 14 in/hg at idle. It pulls great for being such a mild motor in a heavy boat. It'll go sideways at 50mph when you open it up, I just need to get the idle situated

I'm assuming that the clusters ain't dripping from too much psi (& wouldn't think bad needle/seat cuz it has been kitted & likely a new filter, that it is definitely an idle circuit prob. some cluster gasket are cut poorly. did this carb idle OK any time prior to this. check the transfer slot when you can. what is the idle speed? EDIT you pretty much duplicated the OE jet/rod orifices?, maybe a bit richer which is good as all OE AVS's are lean & AVS strip kits are pretty much non existant tho I dont think the main metering would be into this if the transfer slot is pretty much a square

It has never idled right since I got the carb. I still have the factory rods and jets for it, I just changed over to the newer two step setup for tuneability. With the factory jetting, it was ridiculously lean at cruise, to the point it would miss and buck. I'm really not set on keeping this carb for any originality reasons. Nothing on this car is original. If I do start modding this carb though, there isn't any going back. That's why I was originally wondering about the Holley or the Thermoquad. I've had the TQ running like EFI on many engines in the past, and the Holley has been freshly gone through. Id almost rather pull the AVS and stick it aside if I'm going to have to start drilling passages open and modifying it

You are running the flat metering rod covers , correct , when you converted over to edelbrock parts , or did you epoxy the factory ones flat and smooth

Anyways

At idle with engine running , did you remove the metering rod covers and see if the metering rod pistons and rods where all the way down on both sides

it'll work. the tube small end is over .060" in o.d.

I run that same carb on my 71 BEE - 383 Magnum - Put the smaller AVS 6125 s up in the attic

Perfect - Carb is Awesome

I also blocked off the HIC

Made my own flat metering rod covers - Edelbrock doesn't sell them when I asked

104 Primaries
107 Secondaries

68-47 Metering Rods
Blue Edelbrock Metering Rod Springs , had to replace factory springs

Ill have to pull it apart again. Im using the flat metering rod covers from a spare Edelbrock I had laying around. The rods are down at idle and Im using 6 in/hg springs. Ill see about opening up those tubes. If that doesnt make any kind of a difference, Ill just have to try the 3310 or something

You're running 107s in the secondaries with a 383? Damn I'm only running 98s with my 440. I may have to dive into the secondary side once I get it idling right!

I would highly suggest not opening anything up (drilling). we gotta find/fix the root cause first.

The 4640 is for AC cars and I would look at the hot idle compensator for leaks (cork gasket) or block it like bee 71 said. Is your car AC? If not look for 4618 carb, they have different air adjusters. Check the rods to see if they are free moving and down when running, might not be seeing vacuum to pull down (restriction)