Carb tuneup q's (Sorry, very long)
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Member
Joined: Apr 2001
Posts: 377
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From: Everett, WA, USA
Carb tuneup q's (Sorry, very long)
Hey guys, I have always enjoyed the drivability and performance from the q'jet in my other cars, but this one has me vexed.
The symptoms I have are:
On first start up, I give it a full shot with the pedal (supposedly to set the cold idle on the warm up notch) and it starts then drops in about 2 secs to stop. I pump again, and it starts and if I feather the gas, I can get it to continue running, then it climbs to about 2k rpm and will sit there until I tap the gas, then it drops to about 1300-1500 (normal warm up range?)
When car is warm, and I try and punch it to scoot, the car bogs down and won't let go until I let up and bring the gas back on slower, then it hauls like it's supposed to!
Also when warm, the idle is all over the place, but not at once: sometimes it's at around 750 like I want it, sometimes about 1200, and anywhere in between.
My question: Obviously I need to tune this up, but in what steps and which screws and which directions = what effect?
I'm not too much of an idiot when it comes to tuning, however I've never worked on a carb with so much "stuff" on it! The Rochester book I have is not too much help, because I guess I have the one carb that _wasn't_ covered in the book!
So far I've found the idle screw under the linkage driver side, some other screw under the primary pot on pass. side, how do I tune the screws on the pots?
I'm getting a vacuum gauge this weekend so I'll be able to set the primary jets, but what after that?
Please help!!!!!!
Sorry this is so long, but I wanted to provide as much info as I could for the carb gurus out there!
Thanks!
The symptoms I have are:
On first start up, I give it a full shot with the pedal (supposedly to set the cold idle on the warm up notch) and it starts then drops in about 2 secs to stop. I pump again, and it starts and if I feather the gas, I can get it to continue running, then it climbs to about 2k rpm and will sit there until I tap the gas, then it drops to about 1300-1500 (normal warm up range?)
When car is warm, and I try and punch it to scoot, the car bogs down and won't let go until I let up and bring the gas back on slower, then it hauls like it's supposed to!
Also when warm, the idle is all over the place, but not at once: sometimes it's at around 750 like I want it, sometimes about 1200, and anywhere in between.
My question: Obviously I need to tune this up, but in what steps and which screws and which directions = what effect?
I'm not too much of an idiot when it comes to tuning, however I've never worked on a carb with so much "stuff" on it! The Rochester book I have is not too much help, because I guess I have the one carb that _wasn't_ covered in the book!
So far I've found the idle screw under the linkage driver side, some other screw under the primary pot on pass. side, how do I tune the screws on the pots?
I'm getting a vacuum gauge this weekend so I'll be able to set the primary jets, but what after that?
Please help!!!!!!
Sorry this is so long, but I wanted to provide as much info as I could for the carb gurus out there!
Thanks!
Supreme Member
Joined: Sep 1999
Posts: 3,197
Likes: 10
From: Manassas VA
Car: 04 GTO
Engine: LS1
Transmission: M12 T56
Your start up problem is your choke adjustment is off.
Your wandering idle is prolly a vacuum leak, perhaps coupled w/ a bad/maladjusted TPS.
You can search for both problems on this board, both have been covered extensively. If i have the time i'll say more later.
...ed
------------------
Ed Maher - Moderator @ The Carb Board
92 Z28 Convertible - Quasar blue / Tan top
LB9 4L60 GU2 G80 - stock, soon to be sleeper
-=ICON Motorsports=-
- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die
Your wandering idle is prolly a vacuum leak, perhaps coupled w/ a bad/maladjusted TPS.
You can search for both problems on this board, both have been covered extensively. If i have the time i'll say more later.
...ed
------------------
Ed Maher - Moderator @ The Carb Board
92 Z28 Convertible - Quasar blue / Tan top
LB9 4L60 GU2 G80 - stock, soon to be sleeper
-=ICON Motorsports=-
- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die
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