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Detonation

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by tecton, May 29, 2003.

  1. tecton

    tecton 1/2 ton status

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    got me an open element air cleaner in my engine and thats it

    i get some detonation (soudns like backfiring at high rpm's) im wondering if a cowl hood, scoops, or a cold air system would fix this and if so, which and why.
     
  2. Silver84k5

    Silver84k5 1/2 ton status

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    id check timing, and vaccum advance.
     
  3. tecton

    tecton 1/2 ton status

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    my timing keeps falling back

    had a guy set it up 1 (was on 6, he set it 7 advanced) and it ran slightly better...

    would setting it up all the way help?
     
  4. tecton

    tecton 1/2 ton status

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    i mean it was spark knocking...he set it up, it was fine for a day or two, then it started knocking when i start it up in the morning
     
  5. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    A warm running engine will cause "pinging". Using an open element air filter allows the engine to suck in warm air from the engine bay. That may be the cause of your problem.
     
  6. tecton

    tecton 1/2 ton status

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    when im on the gas on the HW it sounds like its backfiring but while im holding the gas down....

    was thinkin scoops...or would cowl be better? i see alot of mud
     
  7. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    What exactly does it sound like? Is it popping out the exhaust or carb on high rpms /forums/images/graemlins/confused.gif... or does it sound more like someones inside your engine beating your piston with a hammer? Like a ping or a knock?

    There should be somewhat of a correlation of what temperature your engine is operating at and how bad it detonates. When its cold it wont happen and when its hot and under load it does?

    What octane are you running? if your only putting in 87 or 89, try filling up with 91 and see if it goes away. Your timing may be too far advanced, if the distribuitor loosened up and moved from like 7*BTDC up to 12 or 14, that could be your problem.
     
  8. BlazerGuy

    BlazerGuy 3/4 ton status

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    It could be an exhaust leak at the manifolds or at the flange...but you should be able to hear that at idle and not just at high RPMs...I don't think that a cowl hood would solve anything though, try putting the stock air cleaner back on...
     
  9. tecton

    tecton 1/2 ton status

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    seems to be only at high rpms up a grade

    im going to have my timing checked tomorrow...gaskets on my headers are fine...and it sounds like its coming out the pipe...
     
  10. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Sounds like its high time for a tune-up. Time it to stock settings unless you've got someone who really knows whats up. Not someone who claims they're good on them there chev-ro-lets.

    Removing all the emissions hoses (also illegal) and playing with the mechanical advacne rate and vac advance amount and then you can get some pretty cool settings in.
     
  11. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    SO is it pinging or missing?

    If it's pinging at mid-throttle, especially under load(like going up a hill), you can bet it's a timing issue.

    If it's missing under load at mid-high throttle, I'd have to say that you've got bad wires/cap/rotor.
     
  12. tecton

    tecton 1/2 ton status

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    its pinging...banging...whatever you wanna call it

    not missing

    it misses whenever i first fire it up and rev the gas...i have to drive it a while for it to stop that
     

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