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Discussion Starter #1
hi guys.im going to try bracket racing tomorrow night and last time i ran i couldnt hear my car with the mufflers so this time i uncorked the headers.i can hear it now.when i rev it up to about 2500-3000 rpm and let off it pops thru the headers.i tried udjusting fuel are mixture both ways and it still does it.is it because of lack of back presure? i checked the timing its at 18 btdc with vacume addvance pluged.motor is a 350.mild cam,around 268-270.headers,torqer intake,holley 650dp.hei with accel coil.thx
 

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The popping has nothing to do with a gasket leak. The free flow of removing the mufflers is contributing to a lean air fuel ratio which will make the engine pop on deceleration.
 

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The popping has nothing to do with a gasket leak. The free flow of removing the mufflers is contributing to a lean air fuel ratio which will make the engine pop on deceleration.
How does this happen?
 

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Discussion Starter #8
Depends on how it's popping back. Only on decceleration is normal.
so its ok then?its only decceleration.i just ont like the sound.i had my head hanging kinda under car when i let off gas it poped and rung my ears lol:)
 

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Less exhaust restriction = more air flow thru the engine = lean mixture

Jet up a couple of numbers, you'll make more hp and the pops with go away.
You mean the air just goes right through the carburetor without causing any extra vacuum to attract extra fuel? I find this to be very disturbing, because I don't any air sneaking through my carburetor without doing any work.
My next question would be, how does the carburetor know when to mix fuel with the air and when to just let air in?
 

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Discussion Starter #12
I love the sound of uncorked headers... Can you shoot a vid of your ride..
my daughter did shoot videos of the races.the car sounded good but i did loose low end power.i advanced the timing but didnt help.was poor air with thunder storms and smoke from fires.i had a blast racing .i won my dot street class.took 1st place and had a blast.my daughters camera wont load the pics on my puter for some reason?gonna try again later.il post some pics and videos.they had some pro mods running as well.man they are [email protected] and sideways.:hurray::beers:
 

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If you lost low end power with open headers try this old trick. Bolt up about three feet of 2-4 inch pipe with a flange welded to it to the header flange. I use a yellow grease pencil, a welder's white marking stick will work. Make a line all the way along the length of the tube. Make several runs. Cut the pipe where there is a noticable difference in the line's appearance from heat.This should be the correct length for an extension and will help.Usually 18-24 inches.
 

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If you lost low end power with open headers try this old trick. Bolt up about three feet of 2-4 inch pipe with a flange welded to it to the header flange. I use a yellow grease pencil, a welder's white marking stick will work. Make a line all the way along the length of the tube. Make several runs. Cut the pipe where there is a noticable difference in the line's appearance from heat.This should be the correct length for an extension and will help.Usually 18-24 inches.
Excellent advice.
 

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And by adding extensions, it improves low end torque.

The extensions should be of the same collector diameter. Optimum design would be 3" diameter inlet to the length needed with a 5" diameter outlet, a cone shape extension.
 

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Discussion Starter #16
And by adding extensions, it improves low end torque.

The extensions should be of the same collector diameter. Optimum design would be 3" diameter inlet to the length needed with a 5" diameter outlet, a cone shape extension.
thx everett.a freind just told me to the same thing.im going to biuld some for next time i go race.il take mufflers off and install short pipe:yes:
 

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You're welcome. You might add an O2 bung to each for later wideband tuning, doesn't hurt.
 

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My next question would be, how does the carburetor know when to mix fuel with the air and when to just let air in?
Carbs don't "know" when to let fuel in, the fuel is always exposed to the air flow and it is released based on how much air goes through the carb. In simple terms, the metering system is the jet, and in your case the jet is too small for the amount of air that is going through. Now having said that, since you are only popping on decelleration, it could be that only your idle circuit is lean, try adjusting that first.

Here's some info on carb theory that might help:

http://www.secondchancegarage.com/public/96.cfm
 
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