whats this screw for (carb)

[brianfulcher15]

 

[sicivicdude]

That's the air bleed screw for the pilot circuit.

It's how you adjust the amount of bleed air to be mixed with the fuel coming in through the pilot jet.

Turning the screw out leans the mixture because there won't be as much vacuum pulling fuel through the pilot jet. Turn it in and the opposite applies, it richens the mixture.

 

[brianfulcher15]

whats the one with the spring on it then?

 

[sicivicdude]

idle speed. It holds the slide up a certain amount bepending on how far you turn it in.

 

[brianfulcher15]

how high should that screw be? or how many turns out?

both screws

 

[sicivicdude]

The air screw should be about 1 1/2 turns out to get a nice smooth idle. If you have the air screw out more than 2 1/2 turns you need a smaller pilot jet if it's less than a 1/2 turn out you need a larger pilot jet.

The idle set screw needs to be screwed in far enough to leave ABOUT a 1/16 of an inch gap under the slide. That number is not necessarily exact just a round figure.

 

[brianfulcher15]

ok, that should make a bit of difference tomorow when i mess with it again.

 

[brianfulcher15]

i thought the one with the spring was the a/f screw.... and the other screw is all the way in. I bet thats why its like its flooding no matter what jet i put in.

 

[sicivicdude]

The air screw being all the way in will make it flood like mad while it's idling.

The one with the spring on it forces the slide up for idle speed control. The air screw is off throttle and idle MIXTURE control.

 

[brianfulcher15]

The air screw being all the way in will make it flood like mad while it's idling.

The one with the spring on it forces the slide up for idle speed control. The air screw is off throttle and idle MIXTURE control.

right now i have a 40/140 jets in it. with it all the way in it idles, but i just went and turned the air screw out 1.25 turns and it just fires up and dies, doesent idle at all.

tomorrow im goign to put my 48/150 jets back in and maybe it'll be close to perfect.