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I have had several people try to help and I still cannot seem to find the problem. My 66 289 with 4V carb idles extremely high, but when I lower the idle it floods itself out. It is running so high right now it rumbles in park - the hood was shaking while I was working on it. I have also adjusted the mixture screws to no avail.

Does anyone know where I should start? I am thinking that I may take it to a professional - but I would like to know what I should expect from him as far as a diagnosis and price?

Thanks...
 

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Do you have an electric choke? If so loosen it and turn it towards lean until you get the idle better. There should be about, no sure what it is exactly, but about 1/8 inch of space between your butterflys and the top edge of the carb when the engine is warm. When I installed my 2 barrel the idle was also running away on me. The choke was out one full turn..Also , you may have a vacuum leak around the base of the carb, either the spacer to carb or the spacer to block gaskets.This will also cause fast idle and most likely is the problem. Spray a little wd-40 along the base and see if that speeds it up of chokes it. Doesn't take much to find out if that is the leak.Any variation in the sound of the engine will tell you that is the problem. Either replace the gasket with a thicker one, add so gasket maker, gas compatable, or try tightening, or double gaskets.
Don
 

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if the float levels are overflowing, it could act like that. there should never be raw fuel (droplets) coming out of anything but the accelerator pump.

both idle MIXTURE screws shouldn't need to be more than 2 turns out AT WORST (an exception is factory emission holleys early-emission times...they got LEANER as you backed them out, kinda like an idle air adjustment on imports)

BOTH IDLE MIXTURE SCREWS (LEFT AND RIGHT SIDE) SHOULD BE TURNED NEARLY THE SAME AMOUNT!
 

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but when I lower the idle it floods itself out.

By that, am I to assume that you see black smoke pouring out of the tailpipe before the engine dies, yes?

What carb and what build state is the engine (stock, performance, etc)...be specific...

Can you kill the engine by turning the idle mixture screws in (generally CW)?

If you rap the throttle and release, does the engine snap back to the high idle or just settle back...?

How does the engine run when not idling?

When and under what circumstances did this problem start?

Get back to us...
 
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