WOT Carb Problem
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Joined: May 2005
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From: Arlington Virgina
WOT Carb Problem
Hi all,
the car in question is a 1977 L82, with a Rochester QJet Carb. The car idles fine and is fine through about the first 3500 rpms. From a stop with the pedal down to the floor the car takes off fine then about 4k rpms starts to get flooded(or no gas not sure which one), bogs down and almost stalls. Is this a rich or a lean condition or something else? and can the second set of barrels be adjusted by themselves?
the car in question is a 1977 L82, with a Rochester QJet Carb. The car idles fine and is fine through about the first 3500 rpms. From a stop with the pedal down to the floor the car takes off fine then about 4k rpms starts to get flooded(or no gas not sure which one), bogs down and almost stalls. Is this a rich or a lean condition or something else? and can the second set of barrels be adjusted by themselves?
Race Director
Joined: Dec 1999
Posts: 19,610
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From: Forked River NJ
Yes it can. It is providing enough fuel for just driving around but it cannot supply the demand for WOT. I had an old Camaro that would do the same thing. A run through the gears it would be OK in 1st and 2nd by the time I would out 3rd it had emptied the fuel bowl and just bogged down. A new HP fuel pump solved the problem. This might not be it but it is a common problem if your pump has some miles on it.
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Joined: May 2005
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From: Arlington Virgina
btw..it does intermitently backfire through the carb..which is supposed a lean condition...but...it also smells heavily of gas...which is a rich condition...so im kinda stumped. Is there an easy way to test the full pump?
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Joined: May 2005
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From: Arlington Virgina
I think this is my problem. These "rods" can be adjusted correct?
The the problem that i am having just happened all of a sudden one day. Can these secondary rods just lose their settings in one day?(i.e tuesday everything fine, wednesday everything gone to hell??)
Incorrect Secondary Metering Rods
Results in: Poor WOT performance, sags or flat spots going into the secondary side, car “falling on its face” somewhere in the secondary range, smoke at WOT.
Comments: Since the secondary rods are so easy to change, they are frequently used as the “primary tuning tool” on a Q-Jet. This results in some pretty strange rods being installed. Make sure you know which rods are stock for your application, and make changes in small increments from there.
The the problem that i am having just happened all of a sudden one day. Can these secondary rods just lose their settings in one day?(i.e tuesday everything fine, wednesday everything gone to hell??)
Incorrect Secondary Metering Rods
Results in: Poor WOT performance, sags or flat spots going into the secondary side, car “falling on its face” somewhere in the secondary range, smoke at WOT.
Comments: Since the secondary rods are so easy to change, they are frequently used as the “primary tuning tool” on a Q-Jet. This results in some pretty strange rods being installed. Make sure you know which rods are stock for your application, and make changes in small increments from there.
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Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
The carburetor is running out of fuel. If the fuel pump is more than 3 years old change it. Their cheap. Just get a stock pump from NAPA. While you're doing this inspect the entire fuel system.
If you want to go a little richer on the secondaries it certainly couldn't hurt. You can get a CK rod from Edelbrock.
BigBlockk
Later.....
If you want to go a little richer on the secondaries it certainly couldn't hurt. You can get a CK rod from Edelbrock.
BigBlockk
Later.....
Racer
Joined: Jun 2002
Posts: 281
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From: Brookfield IL
If you want to bother, you can verify this by connecting a fuel pressure gauge at your carb inlet and taping it to your windshield. For my car, it revved in neutral no prob, but I could see the pressure drop to around 2.5psi at WOT under load.
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Joined: May 2005
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From: Arlington Virgina
i tested the fuel pump by disconnecting the distributor primary leads and the fuel line to the carb, then tried to crank the engine. Nice spurts of fuel came out. What else should i check on the fuel system? btw, timing is set to 12 degress before TDC like the haynes manual says.
Race Director
Joined: Dec 1999
Posts: 19,610
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From: Forked River NJ
Originally Posted by jerrypc
i tested the fuel pump by disconnecting the distributor primary leads and the fuel line to the carb, then tried to crank the engine. Nice spurts of fuel came out. What else should i check on the fuel system? btw, timing is set to 12 degress before TDC like the haynes manual says.