Backfire, capow!

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

  1. justin has a 74

    justin has a 74 Maverick bandit official

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    Got the car running today after my little head problem. Getting backfire around 3 grand. I was thinking its the pcv hose since its looking alittle cracked.


    Any takes on this? do you think its the pcv valve? dissy was moved a little but back to the original spot. I didnt take it out for the head swap:D
     
  2. don graham

    don graham MCG State Rep

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    I doubt its the PVC. Did you take the wires off. I'd double check them to be on the right plugs. If they are check the timing.:)
     
  3. Bryant

    Bryant forgot more than learned

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    it could happen from the valves floating if you have the wrong or really bad valve springs. you may have a valve that is not seating correctly. does the back fire come out of the intake or exhast?
     
  4. justin has a 74

    justin has a 74 Maverick bandit official

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    How about the hose:rolleyes:. it goes right into the intake.


    Wouldnt the machine shop notice if the valves were not seating properly? They noticed the problem with my other heads.:16suspect

    I think its comming out of the intake, didnt mess with it much since i had to go to college. The only thing i did different this time is that i put a spacer below the carb and i highly doubt thats my problem. Guess ill fiddle around with it when i get home.
     
  5. Bryant

    Bryant forgot more than learned

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    if its coming out the intake, thats usually a lean pop. can be caused from a vac. leak like a pcv valve hose or other.
     
  6. justin has a 74

    justin has a 74 Maverick bandit official

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    Lean pop like richin the mixture?
     
  7. Bryant

    Bryant forgot more than learned

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    ya but if you lean enough to pop out the intake you probly have a vac leak or major issue with your carb. also make sure your timeing is set correctly.
     
  8. justin has a 74

    justin has a 74 Maverick bandit official

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    timing is correct, i checked it twice!


    Powervalve?
     
  9. maverick maniac

    maverick maniac Banned

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    can anyone say power valve ....
     
  10. justin has a 74

    justin has a 74 Maverick bandit official

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    btw the idle is inconsistant and sounds like a funny car!
     
  11. maverick75

    maverick75 Gotta Love Mavs!

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    What power valve did you use? The one from the rebuild kit? Which is a 10.5. Do you know how much vacuum is has at idle?
     
  12. justin has a 74

    justin has a 74 Maverick bandit official

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    I have never changed it:hide:

    I basically bought new gaskets and threw it on for a year. Wiring is good (if you want to call it that) And i just drove it down my driveway at 2000 rpms and had a 7 foot flame shoot out of the carb!!!! with no aparent popping.

    Looks like its a 5 minuter in the garage tonight listening to metallica:party5:

    Dont have a vacumm guage, its probably the power valve. Mabe thats why it was popping at 2500 rpms on the way home last week, or mabe it was that rocker arm that fell off with 2 bent pushrods.:rofl:
     
  13. maverick75

    maverick75 Gotta Love Mavs!

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    Well to get the correct power valve and to set the idle mixture you need a vacuum gauge. You can probably borrow one from the parts store.
     
  14. justin has a 74

    justin has a 74 Maverick bandit official

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    Im just going to get the 6.5 for now. If i need to, ill upgrade in the future. Just need the car to get me to school tomorrow.
     
  15. mashori

    mashori Member

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    I'm confused, why would the power valve in the carb cause a lean pop?
     

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