650 AVS stumbling in hard turns - ideas?

[GoodysGotaCuda]

My AVS, since day one (new) has stumbled in hard turns. Wasn't a huge deal to me, but now it's a bit annoying. I have an electric fuel pump setup, with a dual feed as well. I plan on dropping the fuel pressure like Edelbrock recommends from 6psi to 5.5psi (not sure what it'll do, but I'll go with the recommendation..can't hurt.). I've thought of blocking the fuel transfer port between sides which would maybe help keep the fuel from leaving the jet in whichever direction I'm turning. I've also thought of altering the baffles to help keep the fuel where it should be.

I've played with float levels in the past, with no immediate success. Can't recall what they are set to at the moment.

Anyone have suggestions I may not be considering? Metering rods/springs, etc? 

[Bullitt-]

They have spring-loaded needles and seats for off-road.

[GoodysGotaCuda]

They have spring-loaded needles and seats for off-road.

Thought about that, but also was thinking how hard of a turn can my basically stock Barracuda really take on good tires? Not doing anything crazy, or really auto-xing the car. Doesn't feel like "normal operation" to me.

[UKcuda]

I have a 625 AFB on the Mustang which does the same thing, but only turning right ?

I always thought it must be a fuel level thing although the levels look OK. 

Little bit of historical trivia: Ive heard when they started over here trying the baby Buick V8 in the Rover's in the '60s they had this same trouble, which is why they went with twin SU carburettors instead of a 4-bbl.

[Chryco Psycho]

the spec for the float is 7/16 I think , I have always found this to be too low 5/16 -1/4 works better

[Bullitt-]

I have a 625 AFB on the Mustang which does the same thing, but only turning right ?

You've got the NASCAR model.....Left turns only.   

I notice that they ave a dual feed for the Thunder series donno if that would work on the AVS.

[GoodysGotaCuda]

the spec for the float is 7/16 I think , I have always found this to be too low 5/16 -1/4 works better

May be worth trying, thanks Chryco

[moper]

Yeah, I'd try raising the float first. Are you accelerating during the corner or just any time you keep a constant throttle and turn left?

[quagmire]

My 800 AVS does the same thing.  I've played with the float level, but nothing seems to help if I'm really getting into a corner.  It seems to be a problem with this carb design.  The floats don't seem to be the problem, the fuel actually sloshes around and spills into the mains.  At least that's what I read in my Carter book.  My wideband shows the A/F spike crazy rich too, so it makes sense.

[GoodysGotaCuda]

Yeah, I'd try raising the float first. Are you accelerating during the corner or just any time you keep a constant throttle and turn left?

Constant, off the throttle or accelerating. Will do it at any point really

My 800 AVS does the same thing.  I've played with the float level, but nothing seems to help if I'm really getting into a corner.  It seems to be a problem with this carb design.  The floats don't seem to be the problem, the fuel actually sloshes around and spills into the mains.  At least that's what I read in my Carter book.  My wideband shows the A/F spike crazy rich too, so it makes sense.

As in 'too high' of a float level would act. There is a column on their 'flow chart'  for 'stumbles/stalls under hard braking'. States to change the float level from 11/32" to 7/16". Which, in my head, would lessen the amount of fuel in the bowls. Correct? Should be fairly obvious if you are going in the right direction or not, if float level will cure it.

[femtnmax]

The float level must be set as everyone mentioned.  Installing the off-road needles and seats is a very good idea.  Fixed the engine stumbling problems I was having on the AVS on the work truck. 
Have you tried one step lighter spring for the metering rods, to keep the rods "down" at a lean setting when decelerating, though this could change the way it runs at other times of course.  I really dont think this will help, but maybe worth a try.
I noticed on the AVS with the float level set per spec, the fuel level is at or close to the gasket where the booster venturis attach to the main carb body, and with the way the booster leg is pointed toward the float bowl it would not take much fuel "sloshing" to have fuel run UP booster leg and spill into the primary throttle bores.  If this is true I can't think of a way to fix it, baffles won't help.
I believe the thermoquads had the booster venturis "up" higher relative to the fuel level, maybe to correct this fuel slosh problem.   I used to have a 340 duster with thermoquad that was put thru 4 wheel drifts all the time...never had engine stumble ever;  just GO GO GO!!

[quagmire]

Yeah, but it's a trade off.  Drop the float level too low and you starve the engine on hard accel.  Mine is set lower than stock, pretty sure 7/16".

[femtnmax]

States to change the float level from 11/32" to 7/16". Which, in my head, would lessen the amount of fuel in the bowls. Correct? Should be fairly obvious if you are going in the right direction or not, if float level will cure it.

Yes, would lessen the amount of fuel.   Its worth a try, especially since they recommend it.

[GoodysGotaCuda]

Yeah, but it's a trade off.  Drop the float level too low and you starve the engine on hard accel.  Mine is set lower than stock, pretty sure 7/16".

Eh, I'm not sure if it will effect mine as much. I do have the dual feed setup, there is plenty of fuel getting to the needle/seat. I do have the "high flow" needle and seat they offer. Dropping it down may be my best bet. I'll try it out and see how it does this week sometime. Have to find the line between starving and flooding. Shouldn't be too bad.

[moper]

Somethign else T-Quads have is tubular vents rather than the wells of the AFB. It would seem to me it's float height related... the down side is the float setting affects everything else that uses air to pull fuel out the boosters...lol. How sure are you it's fuel related? Is ther any chance any wiring not held in palce somewhere is causing it? I had a dart that when you swerved hard enough the front lights would flicker...