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Single weber downdraft on a GM 292

Discussion in 'The Hokey Ass Message Board' started by bodi, Feb 15, 2012.

  1. I have no experience with the Weber downdrafts, but, am interested in possibly running a single 2bbl downdraft instead of the monojet.

    Im interested in something like the 44 IDF, or 48 IDF. I will obviously need to research the CFM to match, but, that is the style I am interested in. Can anyone fill me in on the potential problems I may encounter when running one of the downdrafts on a Chevrolet 292 in a street driven (daily driver) 1964 4 speed 1/2 ton pickup. I'm mostly interested in trying this on this pickup in research for future powered earlier roadsters/coupes, but, want to run one on this pickup for now.

    Help me out if you can!

  2. mike c
    Joined: Jan 14, 2006
    Posts: 61

    mike c

    Check with redline in Gilroy,ca. They may have a kit to fit a IDF to a inline intake. Also check some of the inline forums for additional info. I may have the adapter that fits the GM intake. Let me look for it. Thanks. Mike cain. 607 426 5598
  3. mustangsix
    Joined: Mar 7, 2005
    Posts: 1,341


    IIRC a 44IDF should flow enough to be more than adequate as a replacement for the monojet on a 292.

    The CFM is hard to pin down because the venturis are swapable and the airflow can be adjusted for your application. You can tune these things to run on anything from a VW bug to a BBC.
  4. If you are going to make a manifold,,,why not use a sidedraft carb ? One less turn and a lower hoodline for the future use.

  5. I have a question that is off topic for this thread but maybe someone could answer it for me. What does IIRC mean?

    Now onto the question. I am a big fan of the webers in a racing application but I do not care for them on a street driven vehicle. I would lean toward a del ortho or a solex copy of wither if it were me.

    If looks were not a concern a single weber/Holley 2 bbl is actually a better choice for a street driven 292. or a single holley 4 bbl. never the less I do understand the looks aspect of it and I am assuming that the idea is to run one or more of these carbs on a hoodless application.

    So all that said if i had to run a weber I would lean toward the 44IDF for its ability ti be tunned to match the application. Unless you get lucky right out of the gate it is going to be difficult to get it nailed down initially but once you get it figured out it will be the one to have to meet as many different applications as are avilable with the engine in question.
  6. I have 4-48 IDFs on my roadster and 4-48 IDA's on my coupe with a 327.

    IDF's are more tunable, but once calibrated , they both are exceptional units.

    your 292 may need 2 carbs, is the motor stock ? headers ?
  7. Ok, so I've read that the 44 IDF is roughly 420cfm, so, cfm wise that would be a realistic size to use. Maybe a little much for a stock engine, but, I could step down to a 36 IDF.

    Can anyone with experience running these IDFs tell me what you think about running a single on the street. How are they to live with? Are they fairly reliable? Is there much to tuning them? With just a single I wouldn't think they would be hard to tune at all.

    This would be a single downdraft on a 292 inline intake. Thanks!


    You guys are fast! This would be on an internally bone stock 292 for now.. It has Langdon cast split headers, and an HEI in it. It's in a 64 C10, but, I have some other 292s that I plan on putting in a hoodless light vehicle.
  8. 48 IDA's are 484 cfm out of the box. Webers are extremely reliable, tuning is a breeze with 4 carbs (my opinion), one is a cakewalk.

    Don't be scared of them. they are better than any carb on the market in my opinion and throttle response is crisp.
  9. zman
    Joined: Apr 2, 2001
    Posts: 16,663

    from Garner, NC

    If I remember correctly.
  10. I have many people telling me to just go with a 4 bbl Offy or Clifford intake for simplicity, but, I'd really like to do something a little different, and the beauty of those velocity stacks is hard to deny! It may be just the ticket for my little Bonneville push short box. The IDFs really aren't all that expensive directly from Weber.

    What kind of mileage do you guys think I could get out of this combo? Could I be competitive with a small 4 bbl setup?
  11. New question,

    What would you guys do to convert the linkage from the 64 C10s Rochester B to the 44 IDF. It appears that it would need to be turned 90* to work. I doubt there are many kits out there for that. I guess I could switch to a cable, but, I'd like to keep that stock Chevy linkage out through the fire wall.

    Also, this pickup will be getting the Advance Adapters Ranger overdrive unit as I will be driving this truck extensively. Do you guys think I could make the 44 IDF compete for fuel mileage with a small Holley 4bbl?
  12. CNC-Dude
    Joined: Nov 23, 2007
    Posts: 1,020


    The only issue I see is what are you going to do for a breather?

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