AVS2 800 carbs

Discussion in 'Fuel and Air Systems' started by midnight340, Jan 10, 2019.

  1. midnight340

    midnight340 Well-Known Member

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    If this hasn’t been posted, and for anyone who is interested:

    I called Edelbrock yesterday and was informed that, yes indeed, there is an 800 version of the newer AVS2 carbs on the way. Annular booster AVS, and they are taking pre-orders now. Shipping soon I’m told. :thumbsup:

    ( public announcement, not meant as invite for bashing of Eddy carbs by diehard fans of those great Holley carbs!!!)
    :rofl:
     
  2. midnight340

    midnight340 Well-Known Member

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    For Edelbrock 750 owners, I'll add this information for anyone that it might help:

    When I first came to this site with some problems a couple of years ago (?) I didn't know much about tuning. Well, it's been an education!! But a lot of fun to figure some things out. Here goes:

    Don't let anyone tell you that you can't tune the 750. Yes, they do in fact have some limitation in the amount of fuel that they will ultimately supply in the secondaries, but for most people I think frustrations lie elsewhere. (This is my experience, my findings, so things might be different for others!)

    I have a 9:1 340 with ported X heads, mild 284 Lunati cam, that likes a lot of fuel with the throttle down, but doesn't need so much at part throttle. Other motors will vary in needs, but here are a few things that might help if you are having problems with:
    Rich idle and smelly exhaust
    Throttle response
    Flat spots, etc.

    Throw away the book!!! Watch the plugs or get an A/F meter and vacuum gauge.
    Biggest help for me was doing these things:

    --Use an accelerator pump from the 800 (#1468)
    --Install .043 accel. pump nozzles/"squirters" (#1475 for kit)
    --Don't be afraid to use bigger jets in secondaries than you use in primaries.

    MY OWN EXPERIENCE!!!
    I run .104's in front (68x42 rods right now) and have .119's in back*
    (*I find that .110/.113/.116/.119 all give me the same A/F readings, so there's the limitation in back that the 800's don't have.)

    My A/F readings:
    Idle 13.5 at 800rpm (max. vacuum) screws 3/4 out
    Light throttle 12.5-13
    Steady cruise at 2200 in town, or highway in O.D. 13.5-14 (4.10's with 518 trans)
    WOT 12-12.5

    (Vacuum reading at WOT is 1-1.5" so carb is sized right)
    Timing 22*/34* total.
    Throttle response is crisp off-idle or from low rpm. Engine pulls good.
    Plugs have a nice tan ring at base of porcelain and light black all around the base, timing mark right at bend of strap.

    I have an A/F meter and vacuum gauge plus a lot of testing, so am fairly sure of my #'s, and am fairly happy with the manual choke 750 right now, but it's faster at the strip if I jet too rich in front to make up for the limitations in back. For this reason I'm going to the new AVS2 800.
     
  3. Hellrats

    Hellrats Still wrenching after all these years FABO Gold Member

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    I like my Eddy carbs
     
  4. Go Mango

    Go Mango Well-Known Member

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    I got the AVS2 650 on my 340. Best carb I've ever bought. Runs better and starts way easier.
     
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    • midnight340

      midnight340 Well-Known Member

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      Good to hear, I've read that the low end response is really good with the AVS2 boosters too. I went back and forth as to getting the 650 or 800, then read in a tuning book I have that if WOT vacuum is under 1" the carb is too big, and if it's over 1.5-2" then the carb is too small. My 750 hovered right between so think I'll try the 800. I'm often told the 650 would be better around town and for general driving. (I think that's true, I used to have a Performer 650, plus I got a bit better mileage with it.) ....But I have this brother I run against at the strip every year and he thinks he's faster (sometimes) so WOT is important. :D

      I'll report back if the 800 seems too big.
       
    • threewood

      threewood Well-Known Member

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      It's about time! I have an 800cfm Thunder that is pretty good and easy to tune. I would love to try the AVS2.
       
    • midnight340

      midnight340 Well-Known Member

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      I just watched the excellent video in the tech section on how to pick the right size carb.
      Since I consider myself to be in the state of always learning, I'm now wondering if there is any downside to going with the AVS2 650 vs. the new AVS2 800.

      I do have the 4.10 gears, about 2800 stall, Cope built 518, LD340 intake, the nice flowing heads, cam is the old Lunati 284 Bracket Master cam, 1-5/8 headers with 2-1/2" exhaust with Magnaflows. Weight is about 3300 lbs. Current 750 carb has crisp response.

      That video would suggest I stay with the 650 to keep more velocity through the boosters. Do the annular boosters and AVS secondary change this advice any?
      (I know 340's always seemed to do well with larger carbs...)

      Just opening up the issue to see what other's experience is with 340 carb size.
       
    • Go Mango

      Go Mango Well-Known Member

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      I'd like to know, because I probably would have bought the 800 if it had been available.
       
    • Go Mango

      Go Mango Well-Known Member

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      With a non factory cam(unknown specs) my 340, 4 speed, 3.91 geared dart seems like it might like a little more fuel at high rpm with the 650. The damn thing overwhelms 245/60-14 tires. Low end throttle response is incredible with the AVS2.