air fuel mixture adjustment

[o1heavy]

looking for some insight on adjusting air fuel mixture


engine is a smog 440 in a 78 D300

carb is a 750 vacum 750
engine seams to run best when the mixture scews are adjusted all the way in

does that mean i need to jet the carb down


thanks for any help

 

[70aarcuda]

it means the engine is sucking air somewhere else........

 

[o1heavy]

ok that makes sense

 

[1wild&crazyguy]

make sure the secondary butterflys are just barely cracked and NOT open too much...then set the idle mix screws to about 1/2-3/4 turns out each. if it's still idling high...close the secondary butterflys more.

the adjustment screw for the secondary butterflys/blades is underneth the base plate on the diaphram side of th carb.

 

[Snake]

make sure the secondary butterflys are just barely cracked and open too much...then set the idle mix screws to about 1/2-3/4 turns out each. if it's still idling high...close the secondary butterflys more.

the adjustment screw for the secondary butterflys/blades is underneth the base plate on the diaphram side of th carb.

I do that adjustment on all the carbs I rebuild,good call.