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Su Carbs Won't Idle

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KVH

KVH

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Seems no matter how far up I turn the idle screws the car won't idle steady. It keeps slowing back down to 500 rpms then quits unless I keep my foot on the gas.

I imagine the mixture is too rich, or is there likely a float issue? Maybe some flooding? There's no fuel filter so maybe dirt is obstructing proper float operation. I did just replace the entire fuel line from the tank.

Any other ideas?
 
I think that turning the idle screw should act the same as keeping you foot on the pedal. Is the screw contacting the arm and the arm turning the shaft?
 
I would check the float and also see if sufficient gas is getting into the float chambers. Put in a fuel filter and check the fuel pump. If you get good response when you put your foot on the gas, apparently gas is getting to the carbs.

Then balance your carbs and reset your fuel/air mixture following the guidelines. Be sure when you balance the carbs that you loosen the "w" clip so you can adjust them separately (you probably know all this) and make sure that the slow idle screws have been screwed down so that they just hold a piece of paper under them and then back them out one turn before you start balancing the carbs.

Make sure the "w" clip is tight when you finish balancing the carbs. Sometimes they can slip.

After adjusting the fuel/air mixture, you should be able to adjust the idle properly.

Of course... it could also be something else... But I'd start there.
 
It was decades ago, but I experienced your problem with my '61 TR3. Took it to the dealer - they found a small blown out portion of the intake/exhaust manifold gasket. I remember them asking if I had experienced a backfire through the carburetors (I had) and that it was possible that would have caused the tear in the gasket. Anyway, with a new one installed, the "falling idle to stall" never returned.
 
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