I tried to reset my choke settings this weekend. I have done it before and figured that it is time to do it again. For the past few weeks, the car has been progressively getting worse. I figured that it is because it is getting cooler outside, but it happens during the afternoon too.

What happens is that it idles fine, but when you move the throttle or hit the gas, it wants to stall. Like too much gas is squirting in or something. I hear a hissing noise... and it runs OK once the rpms go above 2000. After the engine warms up a bit, the car runs normally. That is why I figure it is the choke settings.

So I messed with the screws on the passanger side for the choke blade and the throttle blades. Someone mentioned that they need to be below those little slits in the bore...

The choke blade opens up normally like it should when the carb warms up and is only like 2mm open (snaps shut) when the car is first started. I guess my culprit is the lower screw that adjusts the throttle blades.

Also: Does that screw on top (that pushes on the primary rods) have any affect on the idle?

------------------
1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock... all the suspension stuff... 9-bolt posi disk is in... K&N filter... 93 octane...

-=ICON Motorsports=-

 

The screw "on top" if its the one I think you are referring to is the choke break adjustment. Its on the arm of the little vacuum diaphragm, right? Well, if that's the one then, yes, it can affect the idle becuase it affects the A/F ratio delivered while the choke is on for the first minute or so. Its function is to pop the choke opened from its fully closed position to a SLIGHTLY open position just after the engine starts but before the choke begins to pull off. It should pop the choke plate open about 3/16" in most cases.

If you want to see how close your present setting is then take off the air cleaner, start the engine (overnight cold) and then immediately get out and start moving the choke BY HAND. Try opening it (leaner) and closing it to see what the engine WANTS as far as choking. Then set the adjustment on the choke break diaphragm to give you that setting every time.


------------------
94 Firebird Formula M6- No options but Z rated tires. No mods over $10. 13.5@105.
79 Malibu "beater" w/junkyard 400 SBC, tweaked QJet 4bbl, finally a decent set of heads, a few other tricks. A maddening 13.000001 @ 108 on the motor with little traction. No nitrous runs with the new heads yet.

"One of the last remaining QJet tuners on Planet Earth!"

 

Thanks Damon, but that isn't the screw I was talking about. The one you are describing is adjusted just righ acording to directions you gave me a while ago. My question at the end was about the screw on top of the carb located right between the primary bores. When you open up the carb, it looks like it hits a plate (with a big spike and spring on it) that rests on top of the primary rods (and they have little springs around them). It looks like it keeps them from traveling only so far... what affect does that screw have on idle?

My guess is that if it is too far in, the rods don't come out so far and you will get a lean condition, and if the screw is out too far it will be rich. From bottom (all the wa in), I have it adjusted about 3 full turns out... I am thinking I may need to go out another 1/2 turn or so.