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fuel ratio and headers???

Discussion in 'The Garage' started by pilgrim, Nov 24, 2002.

  1. pilgrim

    pilgrim 1/2 ton status

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    i'am having trouble with dieseling on my rig. i just added thorley headers into a single 3" exhuast with flowmaster 50"s..i heard somewhere that the increase in air flow provided from the headers could cause this, and that the remedy is in air/fuel mixer in the carb.(mines a new edelbrock Q-JET, with ajustable air/fuel).. is this true?? /forums/images/graemlins/confused.gif

    ignition timeing is set at 14 btdc. /forums/images/graemlins/burb.gif
     
  2. jakeslim

    jakeslim 1/2 ton status

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    pilgrim, were you able to fix? I just ordered a new edelbrock q-jet for my 350. I also have headers. Any tips you can throw my way before install would be great.

    thanks
     
  3. dubl_t

    dubl_t 1/2 ton status

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    Pilgrim, I don't know. My guess wuld be timing. True, headers and free flowing exhaust can lean out the a/f mix, especially on a 2 stroke, but remember everythings related and one change can affect the whole "system".
     
  4. pilgrim

    pilgrim 1/2 ton status

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    yeah dubl_t you right about the air fuel ratio staying the same even with the increase in air flow. it was just a thought, /forums/images/graemlins/smirk.gif , turns out the timing was indeed set to far forward 16 dergrees, i backed it down to 12 and lowered the idle to 800 or so. this seemed to fix it, however it just dieseled a little this morning so i'am still playing around with it.. one thing i did notice when i had the head off was (what i thought to be) a lot of carbon buildup on the piston's. maybe i'am running to rich and the carbon is glowing hot??? /forums/images/graemlins/confused.gif I've heard of useing marvel mystery oil down the carb, does this work to remove carbon or is there a better way?

    as far as tips on the carb go, it was a simple install. The edelbrock Q-jets have ajustable air/fuel screws that are not blocked off like the stock carbs. to change it i bought a tool designed for it at napa , it was like 10 bucks. they say it's set right from the factory, but i'am still having issues, not from there carb it works great. but i think getting the truck setup right the first time might save you the headache of carbon buildup. bring you rig down to a dyno shop thats what i'am doing when i'am ready, they can run it and tell it's timeing and air/fuel condition throughout the entire range /forums/images/graemlins/smile.gif it isn't cheap though /forums/images/graemlins/deal.gif Make sure the electric choke has voltage to it, that screwed me up for awhile.
     

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