Carter AVS Setup & tuning book/guide?

[Sir Dodge alot]

Problem now is that the carb stud will barely allow the nut to screw on as the extra gasket(s) will block the stud thread from showing.

And going too high of a stud will not allow a nut to bolt on as the carb float bowl will impede the nut.

I'll try using one gasket above where the carb sits on, if that works I'm happy there.
I'll get ARP stud and nut set when I find a acceptable stud height.

 

[Sir Dodge alot]

Vacuum leak fixed with a 4 hole gasket now sandwiched between the insulator and the carb.
now the idle speed screw has an effect.

Dropped the idle down to 750-850.

New problem, when I rev the engine, the idle is very slow to come back down.
(Another vacuum leak?)

Will be on the look out for the culprit.

 

[CBODY67]

Thanks for the information and your progress.

With the engine at 1000rpm, it is running on the main system, which is why the idle mixture screws are not making any difference in the idle speed/quality. Which can mean that the idle circuit is not working as it should to allow the normal idle rpms.

Those Mr. Gasket-type soft gaskets are for short-term use. As in removing the carb a lot at the drag strip and such. Get an OEM-spec insulator base gasket. Holley and Edelbrock have them, as also might NAPA and such. Getting the carb at the correct height relationship to the manifold will allow the automatic choke settings to work better, too, as it is THAT thicker gasket that all of the specs are done with.

Look through the MasterTech video library to see if there is a video on how to adjust the air bleed screw on the 1968 Carter 4bbl carbs. Then follow those directions.

Below is the AVS OEM-spec carb base insulator gaskets which my '70 383 4bbl AVS takes. The Edelbrock appears to come with studs and the Holley item does not. Notice, too, that they both have inserts in the stud holes to keep from torqueing the carb stud nuts unevenly . . . and causing the base to crack, as a result. Might be able to source either of these gaskets from Summit Racing, too, if you might desire to drive to south Arlkington to get one.

CBODY67

 

[CBODY67]

Vacuum leak fixed with a 4 hole gasket now sandwiched between the insulator and the carb.
now the idle speed screw has an effect.

Dropped the idle down to 750-850.

New problem, when I rev the engine, the idle is very slow to come back down.
(Another vacuum leak?)

Will be on the look out for the culprit.

The idle speed should come back quickly and cleanly, without stalling. Check for any vacuum leaks as that is what usually causes the situation you have.

 

[Sir Dodge alot]

The idle speed should come back quickly and cleanly, without stalling. Check for any vacuum leaks as that is what usually causes the situation you have.

A while back I ordered a similar looking insulator from Fel-pro #60123
Would this still work fine? I'm using it right now.

If not I'll grab the insulator gasket from Edelbrock.
(Potentially different thickness/material composition between the 3 insulators?)

Regarding the insulator gasket, the one I have seems more like a fiber insulator than Edelbrocks rubber composite insulator.

Definitely the rubber insulator seems like it would seal better than the fiber counterparts, i'll get the rubber insulator.

In the meantime i'll look for information regarding the air bleed screw.

Question: would you say Carter AVS's equipped with the air bleed adjustment screw a desirable feature?
Or would you prefer carburetors with 2 mixture screws and no air bleed screw?
Thanks.

 

[Sir Dodge alot]

I found a service manual for 1968 plymouths, going to scour the resources pertaining to adjusting the AVS.

 

[Sir Dodge alot]

According to this FSM, the air bleed screw is not mentioned in the adjustment specs, only the 2 mixture screws that are recessed and staked in the carburetor flange are mentioned.

Will keep looking for the adjustment spec for the air bleed screw.

 

[Sir Dodge alot]

Ok so the above 1968-1969 FSM information is slightly dodgy,
(Not using the correct terminology, no pun intended btw)
The "Air bleed screws" that Chrysler calls them in their service conference slideshows is indeed the "mixture screw" not to be mixed up with the actual mixture screws lower down near the carburetor mounting flange.

Video shot below lists "left hand thread"
CLOCKWISE =LEANER.

Let's dig deeper.

Now we look at the FSM information.
COUNTER-CLOCKWISE = RICHER
CLOCKWISE = LEANER.

From this information I can now say 85% sure that the FSM information coincides with the conference slideshow information.

(Incorrect terminology is all that is mixing me up anyway)

 

[Sir Dodge alot]

The spec for the single "air bleed screw" (located above where the PVC hose attaches to on the air horn)
otherwise not listed is the single mixture adjusting screw is listed below for other engines according to the FSM.

M = MANUAL TRANSMISSION.
AT =AUTOMATIC TRANSMISSION.

340/383 M/AT engines Carter #4611S
1/2 turns out from seat.

383/440 M/AT engines Carter #4711S
1/2 turns out from seat.

I was tinkering with the Air bleed/mixture screw and the engine runs the smoothest/highest RPM at 2 turns out, your results may vary.

(Probably the RPM rises as it's a somewhat a controlled vacuum leak and only AIR is travelling behind the air bleed/mixture screw)

Anywho do chime in, if the information is incorrect, I will try to dig further on this air bleed/mixture screw fiasco.

Below is the picture as referance on what mixture screw/air bleed screw I'm referring to.

 

[CBODY67]

The Edelbrock or Holley base gasket insulators are NOT rubber, but the normal pressed paper material, with metal or plastic sleeves for the carb studs.

The "extra mixture screw" was something that lasted only a couple of model years and was then replaced by what preceded it . . . which was just the normal idle mixture screws and the idle speed screw on the lh side of the carb. It was supposed to help get the carbs past the early emissions standards of the time.

CBODY67

 

[Sir Dodge alot]

The Edelbrock or Holley base gasket insulators are NOT rubber, but the normal pressed paper material, with metal or plastic sleeves for the carb studs.

The "extra mixture screw" was something that lasted only a couple of model years and was then replaced by what preceded it . . . which was just the normal idle mixture screws and the idle speed screw on the lh side of the carb. It was supposed to help get the carbs past the early emissions standards of the time.

CBODY67

Indeed the mixture screw was an emissions gimmick, I guess? I will make this carb work for now, just waiting on the insulator now.

I don't suppose I can "plug" off that single mixture screw as it's part of an inherent carburetor design.

I'm guessing the Description from the website I looked at the insulator is incorrect then. "Nitrile rubber composite"

No matter though, still have other things to do.

Like the throttle adapter linkage setup and such, I don't think the one Edelbrock has might work. I believe it still incorporates the use of a cable instead of the rod setup I have.

I guess I should be glad that at least the motor starts & runs on it's own power!

 

[marty koirtyohann]

Hey there gents, would appreciate some help or finger pointers on this matter.

Recently I was able to do a 2 to a 4 barrel conversion on a 361 motor.
(Stromberg WWC to a Carter AVS)

Problem now is I have no idea where and what to start adjusting to get the Carter AVS running right.

Feels like I'm in the dark adjusting screws and what not like as if I'm blind folded.

Is there some kind of book or guide I can purchase on adjusting & setting up Carter AVS's?

Or is a service manual the better choice?

Additional information: Carburetor came off of a 1968 plymouth roadrunner.

Thanks.

yes u can buy them but they r a pain . ballance the carb it should be close . ifu want to change the jets but thaks a Edelbrock avs tuning kit i think they r a pain ti use all the guys that can help me r too bussy with their own to help me so i leted it set@ factory i when from a juck holley to a avs 750 curb

 

[Sir Dodge alot]

yes u can buy them but they r a pain . ballance the carb it should be close . ifu want to change the jets but thaks a Edelbrock avs tuning kit i think they r a pain ti use all the guys that can help me r too bussy with their own to help me so i leted it set@ factory i when from a juck holley to a avs 750 curb

Well if pre 1970's AVS's are a pain to tune, challenge accepted, or I'll try my best anyway.

 

[marty koirtyohann]

Well if pre 1970's AVS's are a pain to tune, challenge accepted, or I'll try my best anyway.

WELL U CAN GET A BOOK FROM

Edelbrock​

with a kit . u have to use a vacuum gauge its trail & error how is it runing now? dose it idel ok ? dose it stumble when u floor it?
what r u wanting out of it better mpgs? more power?
what cam is in it ? the stock 361 cam?

 

[Sir Dodge alot]

WELL U CAN GET A BOOK FROM

Edelbrock​

with a kit . u have to use a vacuum gauge its trail & error how is it runing now? dose it idel ok ? dose it stumble when u floor it?
what r u wanting out of it better mpgs? more power?
what cam is in it ? the stock 361 cam?

Yes stock 2 barrel cam, getting more power out of it is the goal I guess, just wanted to do a 2 to a 4 barrel conversion just for shits and giggles.

It starts reliably, but there seems to be an issue, RPM is idling at around 850 and the idle screw is backed all the way off And it's still "idling"

I do plan on getting a Eddy tuning kit later on down the line but for now I'm just trying to get everything under control.

Interesting note is that the idle transfer ports are still showing underneath the throttle plate, even though the idle screw is backed all the way off.

Vacuum leaks have been searched and no leaks.

Wondering if there's a hole/leak near the intake manifold mating surface underneath where I can't see.

 

[1970cat]

are the throttle plates rubbing on the base gasket and is there enough tension on the return spring?

 

[marty koirtyohann]

Yes stock 2 barrel cam, getting more power out of it is the goal I guess, just wanted to do a 2 to a 4 barrel conversion just for shits and giggles.

It starts reliably, but there seems to be an issue, RPM is idling at around 850 and the idle screw is backed all the way off And it's still "idling"

Interesting note is that the idle transfer ports are still showing underneath the throttle plate, even though the idle screw is backed all the way off.

Vacuum leaks have been searched and no leaks.

Wondering if there's a hole/leak near the intake manifold mating surface underneath where I can't see.

well r u useing a aftermarket intake? i allways used oem stock like 1 from a 383/400 it should bolt right up as any head / intake well bolt up . a copy of the factory service book for the yr of the car/motor it came off from would help

 

[Sir Dodge alot]

well r u useing a aftermarket intake? i allways used oem stock like 1 from a 383/400 it should bolt right up as any head / intake well bolt up . a copy of the factory service book for the yr of the car/motor it came off from would help

I am running a #2806301chrysler cast intake manifold (1968-1969)

Carb came off of a 68' plymouth roadrunner. Same thing with the manifold, off of a different 68' Plymouth roadrunner.

 

[Sir Dodge alot]

are the throttle plates rubbing on the base gasket and is there enough tension on the return spring?

Yes the throttle plate closes while not rubbing against the carburetor base gasket surfaces. Will look again, but I have a bad feeling that the throttle plate may be warped? Or the shaft is warped?

 

[marty koirtyohann]

I am running a #2806301chrysler cast intake manifold (1968-1969)

Carb came off of a 68' plymouth roadrunner. Same thing with the manifold, off of a different 68' Plymouth roadrunner.

ok then iyt dsouod workunless its warped bug a cast iron intake that is unlikely