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I recently purchased a 68 GTO with a 400, 3 speed maual tranny. This car is an original survivor car with 67,000 miles. The previous owner stated that the Carter Quadra-Jet had been rebuilt recently, and it looks like it has been. The problem lies with wide open throttle the engine does not accelerate smoothly, it feels like it flutters/stumbles thru out the rpm range. The carb installed is a Carter Model 4887 S (F2). I was trying to find out if this is the correct application for the 68/400 motor. I do not think it is running rich, as there is no smoke when putting the hammer down. I am going to try and pull the sparkplugs tomorrow to see if there is any indications of running lean, How can you tell if the secondarys are opening all the way at full throttle applications? Could this be a timing issue? Is there a timing that works best other than what the specs state (retard vs advanced)?

Any suggestions would be greatly appreciated!!
 

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acceleration issues

Pull the air cleaner and look down the throat of the carb (with the engine off), and work the accelerator fully 2 or 3 times. You should see a good stream of gas shooting out of the discharge nozzles at the front. If not, it could be a bad accelerator pump, or a blocked passageway in the carb. Also, there should be a three hole positioning lever at the top of the accelerator pump, sometimes you can adjust the stumble out of it with that. It might be starving for gas. Check carefully for cracked vacuum lines. And with engine running, spray carb. cleaner around the base of carb, and all vacuum fittings- you will hear a change in rpm if there's a leak. Could be improperly adjusted floats, or a number of other things. Before you pull carb. though, thoroughly check your DISTRIBUTOR and ALL electrical components. (Points, HEI, etc...). If you have power brakes, make sure the booster isn't leaking. Post pics. if you can. Good luck.
 
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