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1974 merc 4hp (40) carb

What else have you done?

A carb does not go "out of adjustment" all by itself. If it (was) working fine at one point and it isn't now, fiddling with the screw is not going to do a thing for you.

A crappy idle can be caused by dozens of things -

old gas, bad spark plug, a bad coil or other igintion component, an air leak, a bad gasket, a clogged carb and a number of other things that don't immediately come to mind.

So, need some history here and what have you done to try and correct it...
 
galamb said:
What else have you done?

A carb does not go "out of adjustment" all by itself. If it (was) working fine at one point and it isn't now, fiddling with the screw is not going to do a thing for you.

A crappy idle can be caused by dozens of things -

old gas, bad spark plug, a bad coil or other igintion component, an air leak, a bad gasket, a clogged carb and a number of other things that don't immediately come to mind.

So, need some history here and what have you done to try and correct it...
Click to expand...
well took the carb compleatly apart cleaned all the jets ect replaced fuel lines runs fine on top just cant get it to idle it stalls?
 
Ok then, since you have the idle screw set (currently) at 1 1/2 turns out, try another 1/8 of a turn (out) and see if that improves.

Tweak in 1/8 of a turn increments and give it a few seconds to adjust to your changes.

However, if you make three adjustements and it's still (gagging) on you, the problem lies somewhere else.

But try that first....
 
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