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Discussion Starter #1
i have recently put a fresh motor in my car and put a demon carb on it and cant get it to stop popping through the carb, does any body have any baseline settings on where to set the screws for a starter: i am completly new to carbs i was a efi guy and am trying to learn what to do here... thanks for the help.
 

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i have recently put a fresh motor in my car and put a demon carb on it and cant get it to stop popping through the carb, does any body have any baseline settings on where to set the screws for a starter: i am completly new to carbs i was a efi guy and am trying to learn what to do here... thanks for the help.
You may want to ck valvetrain.Or car is very lean..
 

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I'd go to Barry's website and look up the specs on your carb, compare it to what's in it now, and go from there. If nothing else, it at least gets you back to baseline (out of the box tune) and a good starting point. If it's still popping though the carb, then you'll need to figure out why. Could be timing, vacuum leaks, etc. Biggest thing is not to make any big changes to anything until you're sure everything is right as far as timing, baseline settings, and such. Really sucks to try tuning a carb to find out later you have an intake gasket leaking.......Don't ask me how I know that..............
 

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Discussion Starter #4
im thinking its too fat, when i chop the throttle to rev it up it pops on the 2nd or 3rd chop, it idles fine revs fine its just when i hit it and let off. ill have to check the rockers and make sure there still set, there not ticking though or making any noises.
 

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A pop through the carb is usually a lean condition, check to make sure there is no slack in the accelerator pump arms.
 

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im thinking its too fat, when i chop the throttle to rev it up it pops on the 2nd or 3rd chop, it idles fine revs fine its just when i hit it and let off. ill have to check the rockers and make sure there still set, there not ticking though or making any noises.
Pop through the carb is usually lean

If your vacuum advance is on your PORTED VACUUM that could be the issue

Put the vacuum advance on manifold vacuum if its not
 

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Discussion Starter #7
I. Changed the jets to a 68 in front and a 74 in the rear, its still poppin with a occasional fireball.lol i turned the timing down to 4 degrees(iknow its low butit a start point) and got it to quin poppin for one launch before the battery went dead, my plugs are covered in soot so i know its fat, im thinkin its puddling, any other opinions?
 

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Battery voltage is extremely important. When running at night, with the fan running my car would pop and crack and break up at higher R.P.M. Kill the fan, car ran fine. To big of underdrive pulley and shit battery was the cause. I was 17 and it was in 1994, it was a valuable lesson learned. May not be the issure but I can tell you from multiple experiences that it can and will cause problems. Also its impossible to properly tune a carb when you don't have enough voltage to light the mixture to begin with. Just my thought, start with 12+ volts and a working alternator and go from there.
 

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Discussion Starter #9
i found out something today, its a 850 carb, i was told it was a 650 when i bought it, that would answer why it is way to rich, there is so much fuel its burning back into the intake, its on a 306ci motor im sure you all agree its too big?

i did however come out 2.5 turns on the primarys and it does not pop at all when i rev it up, however when i go to launch the car it still shoots a big fireball. i think its just too much carb.
 

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i think you may have your firing order wrong on the plug wires, so check that first.

that carb is actually extremely lean with those jets. think of it opposite of what you are now. the bigger the carb for the engine size, the lower the signal (draw), and the bigger the jets have to be to create the right a/f ratio.

sell the 850 and get a 650, and the jets you have now will work good in the 650.
 

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i wonder if the power valve is bad or stuck open. it shouldnt be fat. it needs to be 32-35* locked out timing, or about 16* initial and total 32-35 by 3000 rpm.

what cam is in this engine? if the vacuum is extremely low, the power valve could be coming open when it isnt supposed to. check float levels too, maybe its too high.
 
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