Qjet Hunting at idle

[buicksstage1]

I have a Buick 470 stroker, 4.350 bore/3.950 stroke, 10.5:1, Sgt2 SE heads that flow 350/240@.600 lift, Cam is a HYD roller 230/23 @ .050 112 SA .550/.571 lift. 2 inch header, single plane intake and Q950 carb and it made 650hp @ 6100. I am guessing its making 600hp ish now that  I changed the Intake to a Eddy B4B dual plane and a 7042240 Qjet which has Idle bypass air holes. I Used the Third Recipe out of Cliffs book which is a really good book if you do not have it yet. Problem I am having is its hunting @ idle 300 rpm ish. No vacuum leaks, throttle plates look good for position on the transition slots. I pulled the front metering rods out just to see if it would change it and it seems of maybe made it a bit better but still doing it.  Any idea's?       

[buicksstage1]

Bad keyboard sorry.   230/238@.050

[Cliff Ruggles]

Are you seeing any nozzle drip at idle?

Exactly what has been done to it:

LIAB
UIAB
Bypass air (baseplate or throttle plates or both)
Jets
Primary Rods
MAB sizes
N/S size
Float level
Fuel Pressure


....Cliff

[buicksstage1]

Did I screw it up lol? This is a street car that will be drive but is there a better direction for that kind of power other then a holley?                                                                                                                             Idle tube restriction,             0.038
Idle down tube,                    0.062
Upper Idle air bleeds            0.068                                                                                                 
Lower idle air bleeds ...........0.070
Acc. pump discharge holes,   0.028"
Idle screw restriction,           0.095
Main air bleeds,                     0.070
Primary jets,                          0.075
Primary rods,                         0.041
Fuel inlet,                               0.145
Float level,                             0.250
Secondary well restriction,     0.040
Secondary POE restriction,     0.062
Secondary tube restriction,    0.038
Secondary rod hanger,           0.545" (G)
Secondary rods.                     0.410 power tip

[buicksstage1]

Are you seeing any nozzle drip at idle?

Exactly what has been done to it:

LIAB
UIAB
Bypass air (baseplate or throttle plates or both)
Jets
Primary Rods
MAB sizes
N/S size
Float level
Fuel Pressure


....Cliff

I might have it sorted out.

[Frank400]

Good news,

  let us know the outcome and the reason it was happening.

  By the way, from what I recall, this carb number has a very short transfer slot that is 100% OVER the throttle plate, with none showing under, right ?  Just out of curiosity, what size idle air bypass did you drill ? 

             Frank.

[buicksstage1]

I left them at factory I think they were .105 I was wondering if it should be restricted?

[buicksstage1]

Good news,

  let us know the outcome and the reason it was happening.

  By the way, from what I recall, this carb number has a very short transfer slot that is 100% OVER the throttle plate, with none showing under, right ?  Just out of curiosity, what size idle air bypass did you drill ? 

             Frank.

The idle mixture screws do nothing, The throttle plates were to high on the transition slots so I drilled a small hole in them so I could close hem up a bit and still no response. This is the first time I have had a tuning issue with a Qjet. Must be rusty lol   

[buicksstage1]

No One? No idea's? As per Cliffs book used the build 3rd recipe on page 113 114/ Would appreciate any help.

[Cliff Ruggles]

Use the bypass system in the baseplate IF you are off the idle system and pulling in enough idle fuel from the transfer slots and boosters AND no control with the idle mixture screws.

Unless I missed it someplace no mention of how my idle bypass air is being used?

You can also pull a smaller manifold vacuum hose to duplicate some bypass air, lower the idle speed screw, and see if it helps some before actually drilling anything.

Also verify that the distributor isn't adding any timing below 1000rpm's or it may "hunt" some......Cliff