Backfiring Through Carb: 67 Riv

Discussion in 'The Venerable Q-Jet' started by johnriv67, Dec 17, 2017.

  1. johnriv67

    johnriv67 Well-Known Member

    Hey all, just picked up an everyday performance quadrajet(numbers matching) for the 67 Riviera. The car was running badly (but at least running) with the edelbrock that was on it. Now after hooking everything up (except the large diameter rubber hose that is connected to the top of the rear of the intake manifold), I fired it up and it would only backfire through the carb. Anyone have any ideas? I'm thinking vacuum advance or something.
     
  2. Briz

    Briz Founders Club Member

    Do you have the PCV port on the carb plugged? and where did you attach the hose to the vac advance?
     
  3. flynbuick

    flynbuick Guest

    Check for a vacuum leak so the mixture is running lean.
     
    Speedfreak likes this.
  4. johnriv67

    johnriv67 Well-Known Member

    OK I plugged in the PCV hose. I attached the vacuum advance hose to the nipple on the front driver side of the carb. Supposed to be manifold
     
  5. johnriv67

    johnriv67 Well-Known Member

    And also, what do you guys know about stainless steel blocking plates for exhaust passages under the carb?
     
  6. Greg Gessler

    Greg Gessler GS Stage1

    If your using the original 67 intake, the exhaust gases run up to the carb flange surface and must be blocked with a thin stainless steel "gasket". Factory originally used a special gasket against intake manifold to allow exhaust gas to flow up to underside of carb to aid in heating up carb, but stainless shield is required to prevent exhaust gasses from actually making contact with carb.

    Originally carb sat directly on top of stainless shield to ensure best heat transfer.
     
  7. johnriv67

    johnriv67 Well-Known Member

    Thank you for the great info. Where would I get a part for that/how can I do it myself? Do I need to take the intake off?
     
  8. lemmy-67

    lemmy-67 Platinum Level Contributor

    Go to:

    www.quadrajetparts.com

    ...and get the smiley-channel (manifold heater) gasket and a 1/4" spacer with the nylon grommets for the bolt holes. I think they also sell the steel plate which blocks off the smiley-channel. You can install it yourself, just stack them as follows:

    - carb

    - 1/4 spacer

    - steel plate

    - smiley-channel gasket

    - manifold
     

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