Backfire and carb fire! Advice please

Fuel and Air Systems

  1. Geff McCarthy

    Geff McCarthy FBBO Gold Member FBBO Gold Member

    Messages:
    149
    Likes Received:
    44
    Joined:
    Aug 5, 2019
    Location:
    Portland OR
    Local Time:
    3:30 AM
    My 63 SF with a 70 400 and Edelbrock 1407 quit suddently, driving up hill in heat. I thought it might be empty tank, so rolled into station and it took only 13gal.
    then it wouldn't start, and somebody yelled "pump it" so i did.
    It started, and then backfired and burst into flame. Fortunately the air cleaner was off. A short shot of fire extinguisher put out the fire after 20sec or so.
    It then started and I drove home...
    So: the carb is covered in soot. Is it damaged? How to clean?
    Was this vapor lock? the rubber fuel hose was very hot, so i cooled it a bit with water.
    If so, is there external insulation for the fuel hose, to reduce vapor lock?
    thanks in advance for the help!
     
  2. zundel

    zundel Member

    Messages:
    6
    Likes Received:
    1
    Joined:
    Mar 20, 2014
    Location:
    San Antonio
    Local Time:
    5:30 AM


    Years back I tried many different Holley carbs on a 390 Ford. One worked extremely well for about two weeks, then failed as the others. Holleys would back fire through the carb and catch on fire.

    Friend with doctorate degree in Mechanical Engineering from MIT says too lean will cause backfire.

    Edelbrock and Carter didn't ever do that on any of my Mopars....'69 RR, 70 GTX, 70 Barracuda all big block.

    Carb is likely not damaged depending on how long the fire was burning. Maybe take it off, clean it with carb cleaner and inspect for damage. Check your exhaust pipes. Are they light grey and very clean? If they are black I think your mixture is not too lean. Possibly a float level too low inside the fuel bowls? I think Eddy has a float on each side of the carb. Check these.

    I know you can rejet Edelbrock for leaner or richer. After 40 years of fiddling with these things I would say to approach problem solving with moderation and lots of thinking. Patience will save you tons of money and frustration.

    Heat passes more quickly through metal than rubber, so the rubber hose might already be insulated.

    If you stay with it, you will solve the problem. Many people get frustrated and give up sometimes sell their car. That isn't you.

    Think how great it will be when you solve this one. You'll feel like a car genius because that is what you will have become.

    All the best-

    Z



    Don't think you need to insulate the fuel line because stock car/engines did not had no fuel insulation

    People would tell me about a "power valve" problem.
     
  3. Dominic

    Dominic Well-Known Member

    Messages:
    57
    Likes Received:
    45
    Joined:
    Sep 27, 2018
    Location:
    San Diego
    Local Time:
    3:30 AM
    Sounds like it was running lean, one way or another.. Do you have an electric fuel pump by chance? I just had a similar situation happen recently where: car was dying up hill, struggling under load sometimes, etc... Turns out my 20 year old electric fuel pump finally quit. Popped a new one in and works great now. Good luck!
     
  4. Xp29h

    Xp29h FBBO Gold Member FBBO Gold Member

    Messages:
    5,525
    Likes Received:
    6117
    Joined:
    Aug 9, 2013
    Location:
    Maine
    Local Time:
    6:30 AM
    Are you running a newer MSD ignition box by chance? Reason I ask is I was and same thing happened minus the 20 second fire. It only lasted a few seconds. I was running a Holley 650 and had just upgraded(?) to msd ignition. It backfired couple times at the pumps. Able to get it out of the pump area and backfired again.Turns out after checking everything carb, it was the New MSD box!
     
  5. twecomm

    twecomm FBBO Gold Member FBBO Gold Member

    Messages:
    223
    Likes Received:
    248
    Joined:
    Apr 7, 2013
    Location:
    Pittsburgh PA
    Local Time:
    5:30 AM
    Might want to check float levels if you never have. I had a brand new Edelbrock, thoughtn I would remove the air horn and double check the float levels prior to install. When these are shipped ( and probably rough handled in shipping ) there is no support for the floats that can flop from one extreme to the other. One would think that were correctly set from the factory, but mine were way off. On a big block, mechanical pump ? If you have never replaced the fuel pump push rod, it's worth pulling to inspect and check the length, could have effect on consistent fuel delivery. Thermal insulation on fuel lines would not hurt, nor would a phenolic or insulating carb spacer.
     
  6. steve340

    steve340 Well-Known Member

    Messages:
    710
    Likes Received:
    577
    Joined:
    Jul 7, 2018
    Location:
    New Zealand
    Local Time:
    10:30 PM
    It could have been vapour lock - and you can get insulation for the fuel lines and make sure they are not resting on heater hoses etc.
    The carb should be OK you could wash with carb cleaner or just leave it.
     
  7. Geff McCarthy

    Geff McCarthy FBBO Gold Member FBBO Gold Member

    Messages:
    149
    Likes Received:
    44
    Joined:
    Aug 5, 2019
    Location:
    Portland OR
    Local Time:
    3:30 AM
    It is a fairly new E 1407, which i rebuilt, mostly to clean out years of crud. I had trouble setting the new floats, so i used the old, which seemed perfect. I shall re-adjust choke and idle jets, and insulate...and carry fire extinguisher! Thanks to all!
     
  8. Ernie ingling

    Ernie ingling Well-Known Member

    Messages:
    380
    Likes Received:
    271
    Joined:
    Jun 8, 2019
    Location:
    Cocoa Fla
    Local Time:
    6:30 AM
    Just a word of caution if an ABC type was used start cleaning now. Stuff will destroy aluminum
     
    • Agree Agree x 1
    • mopar 3 B

      mopar 3 B Well-Known Member

      Messages:
      10,140
      Likes Received:
      7563
      Joined:
      Aug 25, 2014
      Location:
      Kingsville, MO
      Local Time:
      5:30 AM
      For 20 second burns just open the throttle all the way unless of course the engine isn't running.
       
    • BB BELLA

      BB BELLA Well-Known Member

      Messages:
      466
      Likes Received:
      480
      Joined:
      Jul 27, 2018
      Location:
      Severn Bridge
      Local Time:
      6:30 AM
      just one of the reasons running rubber hose for fuel line on the engine is part of a safety inspection "no".
       
    • Nate S

      Nate S Well-Known Member

      Messages:
      806
      Likes Received:
      704
      Joined:
      Apr 24, 2020
      Location:
      Connecticut
      Local Time:
      6:30 AM
      In all my years of doing this stuff, I’ve never had a car engine running well and then “become lean”. Done it with crusty log splitter engines because some piece of crud got in the jet but not a car that was previously working.

      All the coughs, backfires, spits etc I’ve seen I previously good running engines came from either ignition or mechanical timing related issues. (Including bent pushrods, needed valve jobs, timing chain issues etc).

      So if this car is one you’ve been driving some reasonable amount with generally good results don’t go chasing lean mixtures. If it’s been sitting then go ahead but I’d start with the fuel delivery system and not the carb / mixture.

      The heat part, then the cough / spit make it sound more like a engine that needs a valve job. It’s easy to forget how frequently this was needed back in the day.
       
      • Agree Agree x 1
      • HEMI-ITIS

        HEMI-ITIS STREETER on LI FBBO Gold Member

        Messages:
        12,223
        Likes Received:
        14842
        Joined:
        Dec 14, 2008
        Location:
        Long Island,New York
        Local Time:
        6:30 AM
        Why would you be driving w/o a filter on?? That would have suppressed the fire. Vapor lock leaves no fuel in the bowls and will not restart without help. Start with the timing light and verify the timing.
         
      • Geff McCarthy

        Geff McCarthy FBBO Gold Member FBBO Gold Member

        Messages:
        149
        Likes Received:
        44
        Joined:
        Aug 5, 2019
        Location:
        Portland OR
        Local Time:
        3:30 AM
        I took the air filter off in the gas station to verify that the accel jets squirted. They did. Why would the air filter suppress the fire? Oxygen can certainly get in.
        I made a mistake, I think, by continuing to crank during the fire, with the engine not running. Reason: in General Aviation, if an engine fire occurs, "Shut off fuel" and crank to draw fire thru carb, and not set engine bay on fire. In cars...no fuel shutoff!
        the car ran fine today here in PDX in moderate summer temps. Again, thanks to all!
         
      • myk r sanchez

        myk r sanchez Well-Known Member

        Messages:
        1,921
        Likes Received:
        3455
        Joined:
        Apr 29, 2018
        Location:
        Sun diego
        Local Time:
        3:30 AM
        Just how often were valve jobs needed, back in the day?
         
      • Nate S

        Nate S Well-Known Member

        Messages:
        806
        Likes Received:
        704
        Joined:
        Apr 24, 2020
        Location:
        Connecticut
        Local Time:
        6:30 AM
        I remember picking up maybe 6 cars for cheap, all late 60’s, because they ran like crap. Good cold then as they warmed they got crappy. Would spit and cough as described, sometimes stall. Gave them all valve jobs and they ran great. Not every car needed One but they weren’t uncommon. OP symptoms are similar. Should be on his list to evaluate.
         
      • HEMI-ITIS

        HEMI-ITIS STREETER on LI FBBO Gold Member

        Messages:
        12,223
        Likes Received:
        14842
        Joined:
        Dec 14, 2008
        Location:
        Long Island,New York
        Local Time:
        6:30 AM
        A valve job is on the extreme side! This is a carb or ignition problem.:thumbsup:
         
      • Nate S

        Nate S Well-Known Member

        Messages:
        806
        Likes Received:
        704
        Joined:
        Apr 24, 2020
        Location:
        Connecticut
        Local Time:
        6:30 AM
        Evaluate ... Don't go in there wrenching! A compression test is an easy check though.
         
      • mopar 3 B

        mopar 3 B Well-Known Member

        Messages:
        10,140
        Likes Received:
        7563
        Joined:
        Aug 25, 2014
        Location:
        Kingsville, MO
        Local Time:
        5:30 AM
        Next time keep the pedal to the floor and keep cranking.
         
      • dual fours

        dual fours Well-Known Member

        Messages:
        858
        Likes Received:
        939
        Joined:
        May 25, 2014
        Location:
        york county, pennsylvania
        Local Time:
        6:30 AM
        Carry two fire extinguishers, I do.
         
      1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
        By continuing to use this site, you are consenting to our use of cookies.