Time for my dumb question...

[benoit454]

Ok guys here comes a dumb one, but me and my old man ALWAYS argue over which way it is...

On the quadrajets idle mixture screws, which way do you turn them to lean the mix and which for richer mix?

On my edelbrocks the book says,

clockwise to lean it out, or turning the screws in basically,

and taking them out, or counterclockwise is richer.

my old man says you turn them in for richerand out lets more air in and leans it out.

So which is it for a stock quadrajet? it's on his 84 c10.

[85_SWB]

turning in leans

[Dragster66ss]

Nothing valuable to add, other than I feel ya with buttin heads with the ole man on something that you think is common knowledge (nevermind backed up by the Manufaturer's instructions) LOL.

Happens to us (brother and myself) daily. he's the chief mechanic, so we try it his way and hope for the best.

Its ok tho,, we're glad to have him 'round.

[MylilBowTie]

I'm not sure what carbs do but there are some that adjust the opposite way.

[piecesparts]

Righty Tighty and lefty Loosey. If you turn the screws inward, that closes up the fuel path to the throat of the carb. (where the idle circuit is) The air comes down the throat of the carb and mixes with the fuel as it passes the slottd port on the side of the venturie.

[benoit454]

See I'm pretty sure what he thought was they were idla AIR screws, and controlled the air, and in theory would work exactly as he said, meaning when you turn them in it shuts air off making ir rich and out making it lean.

The way I see it they are for the feul, and taking them in makes it lean.

I told him we'd just adjust the damn thing with the truck running so he'll know for sure it works ok.

Yall know that when you do that turning them in makes it stumble and out makes it raise the rpm's. So then he'll know which is which by doing it.

He fought me on my monte carlo and his black truck both with edelbrocks on them, and finally we done it as the book said, and they were perfect.

[dubdeuce80]

it's always fun to argue with older, more knowledgeable people, then completely prove them wrong

[Yankeelights]

Turning in leans it out, but it's only a minor adjustment on Quadrajets ... impress him by telling him that the primary jets & metering rods do the real idle mixing.

[Ivan D.]

Originally Posted by benoit454

my old man says you turn them in for richerand out lets more air in and leans it out.

Yer old man is correct, but only about a few Q-jets that are computer-controlled, or had some other oddity to them, forgot what exactly. Most Q-jets tho, turning in (clockwise) leans them out, turning out (counterclockwise) enriches the air/fuel mixture.

[Dragster66ss]

Originally Posted by benoit454

I told him we'd just adjust the damn thing with the truck running so he'll know for sure it works ok.

Yall know that when you do that turning them in makes it stumble and out makes it raise the rpm's. So then he'll know which is which by doing it.

He fought me on my monte carlo and his black truck both with edelbrocks on them, and finally we done it as the book said, and they were perfect.

That's Exactly what we do,, and then Thank him for getting it fixed

[piecesparts]

If you guys would get a vacuum gauge and connect it to the intake manifold and THEN adjust the "IDLE AIR" screws, you could get that carb set dead on. It is done like this. connect a vacuum gauge to th eintake at a goo0d vacuum port, suchas the one behind the carb. Now start the truck and turn one of the idle air screws in until the truck idle stumbles; now turn that screw outward while watching the vacuum gauge change. The vacuum signal will get larger as you turn the screw outward. When you reach the point that the gauge no longer is increasing in a vacuum number, turn the screw back inward until the vacuum reading just starts to decrease. NEXT do the other idle screw the same way. Once you have the screws adjusted with a good reding, do the first screw AGAIN---turn it in and then adjust it out to get the largest reading---follow that with the second screw AGAIN. once you have the largest reading set, turn the idle screws inward an 1/8 of a turn---YOU ARE SET. That is the optimum vacuum setting and the best idle air setting on your carb. Don't foget to remove the vacuum gauge and connect whatever it was that you pulled off of the vacuum port on the intake manifold.


I am curious as to what kind of motorcycle had the reverse mix screws? I have dealt with bikes before and all of mine had the fuel mixture screws and not air mix screws. Even the Triumphs, Nortons, and Moto Guzzis. It would make for a different thing to do the air and not the fuel.

[WorkinLonghorn]

I am curious as to what kind of motorcycle had the reverse mix screws? I have dealt with bikes before and all of mine had the fuel mixture screws and not air mix screws. Even the Triumphs, Nortons, and Moto Guzzis. It would make for a different thing to do the air and not the fuel.

I'll take your word for it pieces.I deleted my post. Maybe it was those model airplanes ??? Long time ago!

[piecesparts]

Originally Posted by WorkinLonghorn

I'll take your word for it pieces.I deleted my post. Maybe it was those model airplanes ??? Long time ago!

I am not doubting you, there are many designs out there, I haven't seen them all. If there was somethinig, I would be curious about it's design. Knowledge can get you a free beer sometimes. Besides, I have a real bike freak, and I mean freak; at work. He will wear you out with trivia, it would be nice to be "ONE UP" for once. Life is a pop can---all the fizz is gone by the time you are 21.