• Car Backfires when Started/Just replaced exhaust and rebuilt carb
  • Car Backfires when Started/Just replaced exhaust and rebuilt carb
  • Car Backfires when Started/Just replaced exhaust and rebuilt carb
  • Car Backfires when Started/Just replaced exhaust and rebuilt carb

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  1. #1
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    Default Car Backfires when Started/Just replaced exhaust and rebuilt carb

    Hello. I just replaced the stock exhaust and took out all of the smog stuff from my 75 vette. The car runs but after a few minutes the carb seems to load up and it backfires alot. What would cause that?
    Thanks

  2. #2
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    Backfires are almost 100% due to a lean condition or a vacuum leak when it comes to carbs. I woud look for vaccum leaks first as you took off all the EGR stuff - check the intake manifold for any open tubes. Best is to buy a cheap vacuum gauge to see what manifold vac you are pulling , its a great diagnostic and tuning tool as well. The new manifolds might also be the source of your problems as they might be more efficient and now you are running lean - also check that the manifold gaskets arent leaking and that the exhaust isnt either. When does it backfire - on acceleration or at steady state?

  3. #3
    Car Backfires when Started/Just replaced exhaust and rebuilt carb
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    And does it backfire through the carb, or through the exhaust ("afterfire"). ?

  4. #4
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    I guess it was after firing then because it was coming through the mufflers. It did it about 25 times. what causes that?
    Thanks
    Dillon

  5. #5
    Member Vettehead Mikey's Avatar
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    Looking at all your similar threads, it sounds like something went wrong with either your carb rebuild and/or removal of the smog equipment.

  6. #6
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    After you get done checking for vacuum leaks, check your timing.
    Save the wave

  7. #7
    Member 6880 Mike's Avatar
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    Quote Originally Posted by 73shark View Post
    ...check your timing....
    I agree.


  8. #8
    Member 2VettesMike's Avatar
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    One other thought depending on the carb/filter setup is to check the fuel filter and inlet, could have debris restricting fuel flow.

    Thanks

    Mike

  9. #9
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    well one of the needles in the carb was slightly cracked. When I took the top of the carb off it broke off. I am replacing the fuel filter and want to time it. what is the best timing degree? My car originally had smog equipment since it was a 75 but I tool it all off when I converted it to true dual exhaust. Thanks For all of the suggestions and hope to hear more.\
    Thanks

  10. #10
    Member Vettehead Mikey's Avatar
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    If you've got a stcok distributor, use the stock timing. It should be written on the emission sticker on the firewall or in your shop manual.

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