AVS 2 help

[Doorkicker]

I'm a Holley guy and I don't know much about Eddy's AVS2s... But my buddy has a roadrunner with a 383 and it's running a bit Rich. It's not blowing black smoke but it is getting a bit of build up of carbon in the cylinder and a lot of black soot on the inside of the tailpipes. If it were Holley I would drop it down one or two on the main jets.

What's the best course of action for an AVS2? Bigger rods?

 

[toolmanmike]

I'm a Holley guy and I don't know much about Eddy's AVS2s... But my buddy has a roadrunner with a 383 and it's running a bit Rich. It's not blowing black smoke but it is getting a bit of build up of carbon in the cylinder and a lot of black soot on the inside of the tailpipes. If it were Holley I would drop it down one or two on the main jets.

What's the best course of action for an AVS2? Bigger rods?

Take the top off and double check the floats, needle and seat and the float level. I had heard that many left the factory a little messed up. Also, check the car's fuel pressure. Edelbrock carbs don't like much more than about 4#.

 

[turbine68rt]

In addition to what has already been addressed, does the choke open fully when hot? Were any other lighter step-up springs tried?

 

[toolmanmike]

In addition to what has already been addressed, does the choke open fully when hot? Were any other lighter step-up springs tried?

Exactly. Springs first, then rods, then jets if you need to go that far, only if you need extremely lean or rich change.

 

[R413]

How much idle vacuum?
Idle speed?
Make sure choke is open all the way when hot.

 

[Geoff 2]

Many reasons why the carb can run rich, some stated above. Another reason is if a bigger cam has been installed. What is the idle speed [ in gear ]. Vacuum at idle? Is the idle rough?

 

[lewtot184]

Do check float levels. Vacuum check is a must, especially if cammed up. Do an ignition check; especially if cammed up.

 

[Doorkicker]

Take the top off and double check the floats, needle and seat and the float level. I had heard that many left the factory a little messed up. Also, check the car's fuel pressure. Edelbrock carbs don't like much more than about 4#.

Floats look good. Brand new carb. I have NOT checked the fuel pressure... I'll definitely do that

In addition to what has already been addressed, does the choke open fully when hot? Were any other lighter step-up springs tried?

Choke opens completely, but it may be a bit slow, or too tight on a cold start. That's when you see some black from the exhaust and stumbles
Apologies - again... brain-no-workie with Eddy's I don't know what a step-up spring is?

Exactly. Springs first, then rods, then jets if you need to go that far, only if you need extremely lean or rich change.

My immediate reaction was rods... How are these sized? I presume there is at least one number, perhaps 2?
Seriously... when I say I know notta about these things... I mean it!

How much idle vacuum?
Idle speed?
Make sure choke is open all the way when hot.

I didn't test (I will), but owner said 18ish.
Idle speed is 850-900
When at temp, choke is all the way open.

Many reasons why the carb can run rich, some stated above. Another reason is if a bigger cam has been installed. What is the idle speed [ in gear ]. Vacuum at idle? Is the idle rough?

It does have an upgraded cam... I do not have the specs, but it's relatively mild. This is a daily... rebuilt engine has about 4k miles.
Vac at idle... was told roughly 18... but I need to test.]
Idle in gear is high 700's low 800's
The idle is not rough... once warmed up. It's got a nice "rumble". It sounds great at all RPM. Just a little low on pwr

Do check float levels. Vacuum check is a must, especially if cammed up. Do an ignition check; especially if cammed up.

I'm going to do an ign. check... that's #1 on my list now. I didn't do that... just key-off.

 

[Bee1971]

https://edelbrock-instructions-v1.s3.amazonaws.com/edelbrock/carb-tuning-guide.pdf

 

[TrackPack]

You didn't say, but if it's too rich at idle it's super important to get the initial timing/idle speed/transfer slots and mixture screws in sync.

 

[Bee1971]

He also didn’t state what Model # AVS 2

650 or 800

 

[Geoff 2]

I wish those peddling the 4psi fuel pressure limit for Edel carbs would stop. What it shows is ignorance of carb function. Take the popular 780cfm Holley carb, #3310. It comes with 72 pri & 76 sec jets. That is the datum jetting when the fuel level dribbles out of the sight plug holes. If the fuel level is below the holes, the mixture is leaner, if the fuel level is above the holes, the mixture is richer. Note that the change in lean/rich is small until you get to big changes in fuel level. Carter/Edel work on the same principle, except they do not have sight plugs or externally adjustable needle & seats like the #3310 carb. The Edel carb datum jetting is with 5.5 psi fuel pressure; that pressure coupled with the 0.093" n/seat size & 7/16" float level dimension gives the correct A/F ratio starting point. The Edel & Carter carbs can take 10 psi. The air horn that houses the fuel delivery has interchangable n/seats & floats between Edel & Carter. Edel just copied the Carter. A Carter 625 AFB air horn will fit on a 600 Edel AFB.....& vice versa. Metering rods, pistons, jets also interchange.

 

[Geoff 2]

D'kicker.
I would remove the carb & check how much T slot is showing below the pri t/blades. 0.020-0.040" is good, 0.060" or more is too much. While off, check the float level. Should be 7/16". No gaskets reqd if you are careful.
When re-assembling the carb, swivel the covers on the metering rod pistons so that the pistons are contained, but partly visible. When the engine is idling, the pistons should be down & not moving.

 

[turbine68rt]

This is directly from Edelbrock's online technical data sheet regarding the Performer and Thunder series carbs. Not a personal opinion, but rather simply relaying info from the manufacturer.
"Fuel Pumps and Pressure: Avoid extremes in fuel pressure. At IDLE, there should not be any more than 6.0 psi; if the vehicle has an adjustable fuel-pressure regulator, set it to 5.5 psi."

 

[3sloppydogs]

I'm no expert by any stretch but I can say that installing an A/F sensor setup in my exhaust stream was money well spent. It made carb tuning very easy. It was actually fun seeing the results after changes were made.
So I recommend a that setup to help your problem.

 

[62 Dart Convertible]

I don't know what a step-up spring is?

The step up spring pushes the step-up piston upwards whilst engine vacuum pulls the piston downwards. These pistons are connected to the step-up rods - when the rod/piston is fully down (high vacuum conditions i.e. no/part throttle), the thick part of the step up rod is inside the jet, effectively reducing the available jet area. When the piston/rod is fully up (low vacuum conditions i.e. accelerating), the thin thin part of the step up rod is inside the jet, effectively increasing the available jet area and causing enrichment. Springs are easily replaced and are akin to a power valve in a Holley.

Read and understand the tuning guide linked in post #9. It explains the order and process in tuning.

 

[Doorkicker]

You didn't say, but if it's too rich at idle it's super important to get the initial timing/idle speed/transfer slots and mixture screws in sync.

So, the whole timing this is a bit odd. I removed the vac adv... and the base timing was 12* and total was 24*, only a 12* swing... and IMHO 24* is nowhere near enough. Just out of curiosity, I wanted to look with vac adv on.. base was 17* and total 40*. I don't take that to heart, but does a net of 11* sound right for a vac adv?

He also didn’t state what Model # AVS 2

650 or 800

I'm certain it's a 650. But I will confirm.

 

[Doorkicker]

First apologies for the delayed response... the owner was supposed to come over yesterday. Nevertheless, I'll see him tomorrow at a car show... no works but perhaps schedule a new time to bring it to the shop.

 

[Doorkicker]

The step up spring pushes the step-up piston upwards whilst engine vacuum pulls the piston downwards. These pistons are connected to the step-up rods - when the rod/piston is fully down (high vacuum conditions i.e. no/part throttle), the thick part of the step up rod is inside the jet, effectively reducing the available jet area. When the piston/rod is fully up (low vacuum conditions i.e. accelerating), the thin thin part of the step up rod is inside the jet, effectively increasing the available jet area and causing enrichment. Springs are easily replaced and are akin to a power valve in a Holley.

Read and understand the tuning guide linked in post #9. It explains the order and process in tuning.

Rgr that. Will read the tuning guide for sure.

 

[Doorkicker]

D'kicker.
I would remove the carb & check how much T slot is showing below the pri t/blades. 0.020-0.040" is good, 0.060" or more is too much. While off, check the float level. Should be 7/16". No gaskets reqd if you are careful.
When re-assembling the carb, swivel the covers on the metering rod pistons so that the pistons are contained, but partly visible. When the engine is idling, the pistons should be down & not moving.

Appreciate the advice, but I'm not quite ready for that level of investigation. Not that I'm worried... this is no big deal, but rather this is the first time I've put my head under the hood and I don't want to start ripping stuff off until I've walked through all options... this is a friend I made at a car show and the first time he's asked me to look at it... so I want to be polite and respectful.

I'm no expert by any stretch but I can say that installing an A/F sensor setup in my exhaust stream was money well spent. It made carb tuning very easy. It was actually fun seeing the results after changes were made.
So I recommend a that setup to help your problem.

100%!!! Totally agree. I have them in all my cars and recommend them to folks all the time. They're affordable and definitely beats reading plugs constantly.