1974 Dodge Dart Accelerator hesitation

1974 DODGE DART
50,000 MILES
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MY74440DART
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I have recently rebuilt my demon 850 CFM carb, Everything seems to be working fine except for the fact that regardless of whether it's hot or cold when I First press the gas pedal the car hesitates stumbles and nearly stalls. By adjusting the idle speed screw on the car as the RPMs initially start to go up the carb makes a sucking sound and loses all power from about 1000 RPM to 1500 before it again begins to accelerate. The only way to drive the vehicle is too lightly bumped the gas until you get past that point and then all is well with a smooth acceleration . If somebody could help me out with what might be causing this I would greatly appreciate it.
THANKS!!
Sep 15, 2013 at 5:20 AM
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HMAC300
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what kind of carb is it in what engine an dhas the engine been modified. it could be a vacuum leak or improperly adjust accelerator pump. Or if the engine has been modified the cam shaft may be to large for your purpose.
Sep 15, 2013 at 5:41 AM
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MY74440DART
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The motor is a 440 J series so I believe that is a 1974, I believe it is mostly stock outside of an Edelbrock torkker II intake. I just bought it a month ago and the guy I got it from knew next to nothing about what, if anything had been done to the motor. The carb is a 4 Brrl demon 850 with a mechanical Choke. Just from the way it sounds when I manually accelerate it from underneath the hood as soon as I begin to throttle the car I can hear the air start sucking I assume that's because I am opening the butterflies, When I do this I do not see fuel coming out of the squirter. Should I ? Or does it not squirt enough to see at that low of RPM? My gut feeling is the fuel air mixture is leaning out when I first accelerate, But if that is the case I do not why.

Thanks for your help!1
Sep 15, 2013 at 8:02 AM
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HMAC300
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anytime you press the throttle you should see fuel squirt so either the carb accelerator pump is shot or it's blocked up. If you have a very thin wire you should take the carb apart get some choke cleaner and spray all the hole and run the wire through them as well. then make sure accelerator pump is installed and adjusted correctly. even after rebuilding the carb may have to be adjusted to squirt more by moving the rod to another hole. I'm not familiar with Demon carbs but from what I've seen o f them they are similar to a holley but I sounds as if it's acting like the accelerator pump is putting out enough. I am assuming you are the one who rebuilt this. Also with a large sucking sound take a vacuum reading at idle it shold be around 20" or a little more unless this has a very large cam in it which it would idle probably closer to 1500 because of overlap.
Sep 15, 2013 at 8:07 AM