Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor

Idle Circuit Recipie Problems

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Novarolla05:
Hi all,

I'm pretty new to Quadrajets, but not carbs in general. I have a 17059201 Quad that was on a chevy 350 I bought from a friend. It ran perfect, but the cam was a bit much for a daily driver (my friend can't find the specs on the cam he put in it unfortunately). I swapped cams for a milder one, but now I can't get the carb dialed in. The idle is horrible even after rebuilding and modifying the idle circuit per Cliff's first recipe. It seems the idle is way too lean. Here's what I have:

79 chevy truck 350
stock heads/rockers, about 8.5:1 compression
Edelbrock Performer intake
Comp XE256H cam 212/218 @ 0.50   LSA 110

Right now, I have the carb idle circuit for recipe #2 and it still seems lean, and has bad off idle hesitation.

Idle Tube .038
Idle Down Channel .055
Upper Idle Bleed .067
Lower Idle Bleed .070
Single Main Bleed .050
72/52M

I'm just confused on what to try next. Any help would be greatly appreciated.

Thanks,
Richie

Shark Racer:
FWIW, I built a 17058228 for my 78 Corvette with a 216/216-110 cam. I'm pretty sure I had less static CR than you. I had to go even heavier on the idle DCR. I ended up doing 038/059, this got me just a bit too rich(mid 13s AFR). If I did it again, I'd do 038/057. (there's a metric size, (1.45mm, that ends up at .0570).

Novarolla05:
Thanks for the reply.

I'll try opening up the restriction more tonight and see what happens. I'm trying to get the best mpg possible so maybe I've been playing on the lean side too much. Would making one or both of the idle bleeds smaller give the same results?

Thanks,
Richie

Novarolla05:
No luck so far. I've been battling this for several months now, and honestly its getting hard to not just put on the Holley I have laying around  :-\ I don't really want to admit defeat though. I set the idle mixture for highest vacuum, and did the tip in procedure for the APT. The hesitation is much less noticable but still there. Here's what I changed today

Idle Restriction .059
Upper Idle Bleed .070 (I was wrong on my first post  :-[)
Unplugged idle bypass air .055 (Just something else I felt like trying)

It only stumbles if I ease away from a dead stop. If I hammer on it, it doesn't miss a beat.

Any thoughts?
Richie

TommyK:

--- Quote from: Novarolla05 on April 30, 2013, 05:19:16 PM ---No luck so far. I've been battling this for several months now, and honestly its getting hard to not just put on the Holley I have laying around  :-\ I don't really want to admit defeat though. I set the idle mixture for highest vacuum, and did the tip in procedure for the APT. The hesitation is much less noticable but still there. Here's what I changed today

Idle Restriction .059
Upper Idle Bleed .070 (I was wrong on my first post  :-[)
Unplugged idle bypass air .055 (Just something else I felt like trying)

It only stumbles if I ease away from a dead stop. If I hammer on it, it doesn't miss a beat.

Any thoughts?
Richie

--- End quote ---

What size are the idle mixture screw holes?

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