Carter AVS Rebuild...any guides?

[kawahonda]

I'll remove air cleaner and check the squirt action.

Yep, I have the thick gasket on there to help with heat soak issues.

Edit: The pump action works. It's pretty immediate when pulling back the throttle.

The linkage that drives the chock plate doesn't appear to be in a bind.

[Bullitt-]

Stumble could be Idle transition slots are exposed... solution is to back off the idle screw which may or may not require more advanced timing

about half way down in this article 
http://www.superchevy.com/how-to/45638/

Item #2 is a transition slot

[RUNCHARGER]

Choke rod may need lengthening to correspond with the increased base gasket height. It was working before so your crossover passage in the intake shouldn't be the issue.

[kawahonda]

Interesting. I can see those slots, but there's no real accurate way to measure how much is exposed when the carb is installed.

So basically, the more the idle screw is turned it, the more that these are going to be exposed. If I backed off, I would lose my 900 RPM idle and it would probably go to like, 800-850 or something like that.

Oh well, I'll see if that has something to do with it. I don't feel comfortable giving the car more timing yet as I would need to test WOT which I cannot do quite yet because I'm breaking in my new gears.

My timing is currently at 16 initial. Idle/fuel mixture jets are spot on, and manifold vacuum is a very steady 17 inches.

So how does this heat crossover choke rod work? Should it cause the choke flap to close when it's cold? How does the operation work? Or, does one pedal press to the floor close the choke for cold start operation?

[Bullitt-]

could the small spring be the one that goes to a the accelerator pump arm?

[Bullitt-]

So how does this heat crossover choke rod work? Should it cause the choke flap to close when it's cold? How does the operation work? Or, does one pedal press to the floor close the choke for cold start operation?

one accelerator pedal depress should set the choke .... Here's an article with complete details
https://www.hemmings.com/magazine/mus/2009/10/The-Lost-Art-of-Choke-Adjustment/2144991.html

[kawahonda]

Nope, the pump arm/spring is all good. That little spring I posted awhile back goes on the vent arm thing that's internal, which I have plugged up.

I drove the car some more. I'm not even sure if it's considered "off idle".

It doesn't stumble from 850-999 RPM as I move the accelerator pedal down. But at 1000 it stumbles, then picks back up as I further push the pedal down. This to me sounds like the secondary air door adjustment, but I may be wrong. This is probably not an "off-idle" problem, since off idle I would assume means stumble right away right from the idle circuit. Mine doesn't appear to do that. It seems like loosening the tension on the air door may be a good idea at this point....either a 1/4 turn or so. I believe loosening is "clockwise".

Regarding the choke, tomorrow I will try this as described in the article:
"When a hot engine is shut off and starts to cool, the tension on the choke spring increases in lockstep with the drop in temperature. The choke plate and fast-idle cam are attached to the spring via the carburetor's throttle linkage. This requires the throttle to be pressed slowly to the floor once to allow the choke plate to close, and needs to be done prior to cranking the engine over. When functioning properly, the full depression of the accelerator pedal will release the choke spring tension being held by the fast-idle cam and screw, while also providing a shot of fuel into the manifold by the accelerator pump. The accelerator pump shot works as a small prime pulse to provide a combustible mixture prior to the fuel being discharged by the venturi booster."

After things are bone cold, I will do on nice slow pump to the floor, and that "should" close the choke. If it doesn't, I'll have to further figure out what is not causing the choke action to work properly. One guess from Runcharger is the thicker gasket...but man, I really need that thicker wooden gasket!

I'm assuming what causes the choke to "unset" is just pressure from the engine (acceleration) that should cause the flap to open once the engine is warm enough. What's warm enough, halfway on the temp gauge (about 8 minutes of idle from cold)? I'm assuming that I should be able to test this as well with the air cleaner off, and a couple hard pulls of the throttle?

Sorry for the questions, I'm just wanting to really learn the ins and outs of the AVS!

[Bullitt-]

There is a choke vacuum pull off that opens the choke once the engine is running...
There should be specs. on how to adjust this in the rebuild kit
I'ts easier to do on the bench with a vacuum source to pull it open

[kawahonda]

Here's mine.

[kawahonda]

Some updates:

1) The stumble appears to be timing related...duh. I rechecked my initial and it was actually 13 degrees...not 16 degrees like I thought. Moved it to 16 degrees and the stumble is just about gone. I will try 18 degrees...probably will cure it. If not, I could try a larger pump nozzle.

2) The choke is definitely not working. I found a diagram in Mike's carb guide, but it talks about set screws and stuff....which I don't think mine has. I'll check out the manual.

[kawahonda]

I wonder if something isn't hooked up right on this side.

The throttle arm doesn't make contact with anything on this side when the choke plate is closed.

[Bullitt-]

I wonder if something isn't hooked up right on this side.

The throttle arm doesn't make contact with anything on this side when the choke plate is closed.

What your describing sounds correct.. When the choke is "on" the secondary's are disengaged

[kawahonda]

So what linkage is actually responsible for actually popping the choke closed during a full throttle sweep? That's probably where I should start.

[RUNCHARGER]

There is a coil in the choke well in the intake manifold that responds to heat. It pushed the rod (which is connected to the choke blade) up when cold to close the choke. On warmup the coil responds to heat and pulls the rod down, pulling the choke plate open. If you raise the carb up away from the manifold this coil won't push the rod up far enough to close the choke blade on a cold start. However it should be pushing the rod up far enough to partially close the choke blade.
With the car dead cold, open the hood, take off the aircleaner and from the right side with your eye on the rod from the intake manifold well to the choke blade crack the throttle open fully. You should witness movement in the choke rod. From there you can tell if it is binding, not pushing up enough or any other problem.

[Bullitt-]

So what linkage is actually responsible for actually popping the choke closed during a full throttle sweep? That's probably where I should start.

I'm in a little over my head on this not having an AVS in front of me but the linkage (Fast Idle Rod) I'm familiar with does not actually close the choke, rather it releases the choke allowing the tension of the choke spring to push up closing the choke flap simultaneously holding Fast Idle Rod up (I think) disengaging the secondaries.   

I notice in your second pic. above that this linkage appears to be dangling in the hole without a clip holding it?????

  I could not find a good diagram of an AVS but this AFB has a similar setup that will ID the "Fast Idle Rod"