e-broc 1403 rebuild q's

Discussion in 'The Garage' started by jones, Feb 11, 2007.

  1. jones

    jones 1/2 ton status

    May 17, 2004
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    this will be my first carb rebuild and have just a few questions.is there a manual somewhere to aid in my adventure?instead of rebuilding to 1403 specs(500cfm),can i rebuild it to flow 600cfm(1406 specs)1403 specs=primary .086 secondary.052 metering rods .065 x.052.1406 specs=primary .098 secondary .095 metering rods .073 x .047 w/ a yellow step-up spring.orange on the 1403.what does all this mean?is there anything else i need to know?please explain and thanks in advance.
  2. diesel4me

    diesel4me 1 ton status Premium Member

    Jul 24, 2003
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    go here..

    Go to www.edelbrock.com

    They have tech manuals online,exploded diagrams,adjustment specs,etc..

    Not sure if you can "change" the CFM rating..you CAN re-jet it richer or leaner by changing jets and metering rods,,but the venturi's are what limits the amount of airflow--not sure if they can be removed,they might be cast as part of the carb body..in that case buying a 600 CFM Edelbrock is the only option..

    I'd leave it at 500 CFM,unless you have a big block ..in many cases smaller carbs improve throttle response and gas mileage,and only a big engine with a hotter than stock cam needs more than 500 CFM...especially if you street drive it mostly...

    I've ran 450 CFM Holley "Economaster" carbs on a few stock 454's I had--they got 15+ mpg,and ran stronger than they did with the 750 CFM carbs I took off when I bought the motors,that were on there..never had any trouble with burnt valves or other woes many guys said I'd cause by runing such "lean" carbs!--the spark plugs looked perfect,a nice tan/brown color,not too lean or too rich.....:crazy:
  3. longbedder

    longbedder 1/2 ton status Premium Member

    Oct 26, 2005
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    Ridgecrest, CA
    A carb's flow rating is simply the volume of air that it will flow at Wide Open Throttle (WOT). This is determined by the geometry of the bores and venturis, and is not changeable.

    The 1406 has larger jets, so that it will have the proper (stoichiometric) air:fuel ratio with the larger mass-flow of air.

    In the specs you mentioned, the first two numbers are the orifice diameters of the primary and secondary jets. The third set of numbers is the base x tip diameters of the metering rods. The rods are tapered from the base to the tip, and they move up and down inside the jets. That's how you get variable fuel flow accoring to throttle position.

    Like diesel4me said, the only reason to change the jets is if you are running rich or lean at off-idle conditions.

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