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quadrajet question

Old Aug 21, 2017 | 02:28 PM
  #1  
ben442's Avatar
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quadrajet question

carb Number is 7041253

I may have left the float adjusted slightly high when I rebuilt my carb. Would this cause the carb to run rich?

I have adjusted the idle mixture screws to a point where I have the greatest amount of vacuum.

Plugs show light brown in color with some carbon build up.

Hope to find some tuning help here.
Thanks
Old Aug 21, 2017 | 04:49 PM
  #2  
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Originally Posted by ben442
I may have left the float adjusted slightly high when I rebuilt my carb. Would this cause the carb to run rich?
Yes. Since the fuel level in the bowl is higher than spec, the main circuit will start flowing sooner than designed.
Old Aug 21, 2017 | 08:51 PM
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Isn't it more than just the possibility of the engine running rich? Couldn't it also flood? Fuel leak out of the carb and onto the engine? Smell of gasoline in the exhaust?
Old Aug 22, 2017 | 12:20 AM
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is there fuel dripping from the primary nozzles at idle? you may need a flashlight to verify this. the primary throttle blades should be as pictured at idle. if not you may be crutching another problem, retarded timing, vacuum leak. also were gasket surfaces and throttle shaft play checked during the rebuild? older carbs tend to bow(warp) from overtightening and require thicker gaskets or resurfacing. good luck
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Old Aug 22, 2017 | 06:22 AM
  #5  
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Originally Posted by jaunty75
Isn't it more than just the possibility of the engine running rich? Couldn't it also flood? Fuel leak out of the carb and onto the engine? Smell of gasoline in the exhaust?
All various degrees of the same problem of high level in the float bowl. Depends on how high the float is set.
Old Aug 22, 2017 | 08:51 AM
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The issue I was having was a fair bit of exhaust smoke when I was getting a bit aggressive on the pedal. Although I suspected the float to be set a bit high, I found the secondary's choke to be stuck closed against the little ridge at the top of the carb body. I guess that equates to too much fuel and not enough air.
Stay "tuned" everyone

Last edited by ben442; Aug 22, 2017 at 08:55 AM.
Old Aug 22, 2017 | 09:08 AM
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Pretty hard to judge how the carb is set up by looking at the plugs with today's fuel. I find the fuel today has a terrible smell to it. Especially when when you pull into your garage after being out for a good run. You get a certain amount of fuel evaporating. Stinky stuff. Good luck with your tuning. The quadrajet is an awesome carburetor!
Old Aug 22, 2017 | 09:20 AM
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Originally Posted by OldsAl
Pretty hard to judge how the carb is set up by looking at the plugs with today's fuel. I find the fuel today has a terrible smell to it. Especially when when you pull into your garage after being out for a good run. You get a certain amount of fuel evaporating. Stinky stuff. Good luck with your tuning. The quadrajet is an awesome carburetor!
This is a very good point. An A/F meter is really necessary today.
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