Racing Fuel Systems

I guess I will start this off and be the first one to post. I have been looking at the primary, and secondary passages on the Carter/Edelbrock carbs and have a couple of questions maybe you guys could answer for me. I'm looking at the primary idle air bleed that is on the top, and the by-pass bleed on the side, and the book shows the IFR on the inside of the by-pass bleed. Mine seems to be around .50 in size, but the tube that in submerged in the well in .31. I read somewhere about tuning the IFR, or economizer like they call it like you would a Holley, but with the tube only being .31 what would be the use? Wouldn't you just work with tube in the well, or am I over thinking this.
Thanks,
Mark

I'll try to get Tuner to chime in here.

You are correct, the idle jet is the pinch at the tip of the tube in the main well.

The calibration of Edelbrock and other AFB clones has not been consistent and occasionally suffers from the 2nd IAB being too large. Sometimes the idle jets are too large or different size in the same carb. Sometimes the 1st IAB orifice in the top of the cluster is dinged like an attempt was made to press a MAB tube into it, as if the left and right clusters were mixed up in the assembly process.

In old Carter literature the jet between the two air bleeds is called the "Economizer" because it provides the means to limit idle/transition circuit flow to reduce fuel consumption.

Because fuel from the idle jet is mixed with air from the 1st IAB, the mixture of fuel and air is then compressible and so can be reduced or limited by the effect of "sonic choke" when it passes through the Economizer restriction.

https://www.google.com/search?client=fi ... onic+choke

Idle circuit in direction of flow.
1. Idle Jet
2. 1st Idle air bleed
3. Economizer
4. 2nd Idle air bleed
5. Transition slot
6. Curb Idle mixture screw.

Thanks Tuner, it seems the economizer should not be messed with. I am looking into a WB02 to buy to use on this, and my other car. I have read some about the by pass being to large on most of these carbs, and people just put a piece of wire to make the hole smaller. I have posted on the old forum about which 02 to get. May help me some.
Mark

I tried messing with the "economiser" restriction and butchered it in the process. So I just removed it drilled the cross passage so it matched the others and blocked the first idle air bleed to make it function like the Holley design and low and behold that's exactly what it did. It then tuned with the 1.5 usual turns and idled like the holley did before it.

The idle was far better with the Carter design.

Also read this patent which discusses the concept:https://patents.google.com/patent/US4099503A/en?q=carter+idle+circuit+carburetor&oq=carter+idle+circuit+carburetor&page=4

Thanks for the reply Hysteric, did you close off the bleed on the side of the booster, and just used the top bleed, and did you open it up more?
Thanks,
Mark

That's what I was thinking. I'm going to do this to mine. Thank you.
Mark