Backfire, capow!

Discussion in 'Technical' started by justin has a 74, Aug 30, 2010.

  1. Bryant

    Bryant forgot more than learned

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    sure, power valve.
    i dont think its the power valve. if the valve was bad it would be flooding the motor at idle and low rpms. if the valve was too low of a vac level then its possible to cause a lean condition but this sounds more sevear. the accelerator pump would be a more likely canidate to cause that type of back fire than the power valve.
    ill say it again. power valve. probly not the problem.
     
  2. Bryant

    Bryant forgot more than learned

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    the 6.5 is probly way too low for your motor. your beter off geting the highest number like a 10.5. the will make it richen up earlyer. the 6.5 will let it stay on the lean side longer.

    oooh wait. they said power valve because the back fire can damage a power valve. if the car is idleing like before the power valve is still ok. if it wont idle then its bad.
     
  3. justin has a 74

    justin has a 74 Maverick bandit official

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    ITs idleing different now.... but now my valve train geometery is right. Ill let you guys know tonight with the final verdict. PLACE YOUR BETS NOW!


    If anyone has been reading my threads, when my rocker arm popped off, I was hearing a popping, like a backfire but i thought it was an exhaust leak. I wasnt shooting flames out of the carb but after 50 miles of constant popping, i could have just destroyed the valve. The exhaust rocker was the one to pop off and the intake psuhrod was bent.
     
    Last edited: Aug 30, 2010
  4. Bryant

    Bryant forgot more than learned

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    did you forget to put the accelorator pump lever back under the arm when you took the bowl off?
     
  5. justin has a 74

    justin has a 74 Maverick bandit official

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    It was eather 4.5 or 6.5


    Who said i took the bowl off?
     
  6. maverick maniac

    maverick maniac Banned

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    well every thing is new but the carb so that was the last thing I can think of timming is right and the firing order ..new cam lifters heads timing chain all new motor so that leaves the carb . any other sugg,,
     
  7. Jamie Miles

    Jamie Miles the road warrior

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    I'd check the compression, and get a vacuum gauge before doing anything else. Triple check the firing order as well.
     
  8. Mavman72

    Mavman72 Gone backwards but lookin' forward

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    Do you have pedestal type rockers or stud mounted rockers??? If stud mount type you may have a miss adjusted intake valve or three. Are you useing the correct length pushrods for your application??? I would check the condition of your power valve as well, chances are good you popped it with the back fire out the carb.
     
  9. Bryant

    Bryant forgot more than learned

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    there was mention of the gaskets being replaced on the carb bowls. you may have a vacuum leak in the intake gasket. have you fixed that pcv hose yet?
     
  10. maverick75

    maverick75 Gotta Love Mavs!

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    also check to see if it has the power valve protection check ball. I think 93+ carbs have em. If you dont have it a good backfire will ruin the valve.
     
  11. justin has a 74

    justin has a 74 Maverick bandit official

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    i think the carb is a 2000, The carb hasnt been opened for over 6 months. Its not shooting flames but its shooting gas up the carb. The baseplate of the carb was a little wet when i took it off (i know it was just running but...) The gasket could be the problem so i guess ill get another one tomorrow. Carbs not leaking, timing is correct, heads have been cleaned and checked, pedestol rockers.

    Also i went to adjust the needles and the car idled alot beter as i tightened them all the way, isnt the car suppost to die? lol. Somethings screwy!!!!


    Ill replace the baseplate gasket tomorrow and pull the valve covers and spin everything around.
     
  12. justin has a 74

    justin has a 74 Maverick bandit official

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    Ive done enough intake gaskets to get it perfect. And yes i replaced the hose but noticed some gasoline in the hose itself.:hmmm:
     
    Last edited: Aug 30, 2010
  13. maverick75

    maverick75 Gotta Love Mavs!

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    When the needles dont have an effect on the engine its usually a vacuum leak. But to set them correctly you need a vacuum gauge. Also where is it shooting gas from? The vents?
     
  14. justin has a 74

    justin has a 74 Maverick bandit official

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    Straight up the horn. Its probably that dang carb gasket. But usually its something major with my luck, not a 5 dollar fix.


    The needle had an effect, it ran better but it should have killed the engine (as you know)
     
  15. Bryant

    Bryant forgot more than learned

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    you big back fire might have bent a throttle blade. that could be why the idle mix screws dont let it stall out. or the power valve as said before could have been damged and leting fuel in through its circut.
     

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