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Old 03-07-2012, 09:06 PM
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carb trouble

You can use an oxy-acetylene welding tip cleaner to clean up the air bleeds. Just don't get too vigorous with it, since the tip cleaners are actually little round files and will take off metal.
I hope you sprayed the venturies to get them clean. they looked pretty nasty.
You must adjust your idle speed screw (there is only one and it is on the throttle linkage side of the carb) to get an idle speed of around 500-800 rpm, THEN adjust the idle mixture screws (2, one on each side of the primary float bowl) for "lean best idle". You do this by running them both all the way in, but don't make them tight as you will damage the seat.
Next, with the engine off, turn them both out 3 turns (for a Quadrajet, 1 and 1/2 turns for a Carter).
Start the engine and check the idle speed. Turn the 2 idle mixture screws in or out as needed to make the engine run faster. Turn each one only 1/4 turn at a time, and make sure that they both are the same number of turns out.
Once you have the fastest idle with these two screws, go back to the idle speed screw and reduce the idle back to 500-800 rpm.
Generally speaking, once the idle mixture screw have been set in this manner, they might need only 1/2 turn in either direction to prevent a lean spot just off idle (assuming that the accelerator pump is working correctly).
Again, make sure that you only turn the mixture screws 1/4 turn at a time, turning first one and then the other so that they are both the same number of turns out. If they come out different, then you have a vacuum leak.
If your idle is set over approximately 1,000-1,200 rpm, then your engine will diesel (run on after shutting the ignition off). This is VERY bad for the bearings!
Set the timing now.
After setting the timing, you may have to increase or reduce the idle SPEED screw, but don't touch the 2 mixture screws again unless the engine has a lean bog or miss just off idle.
Good luck.
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