Tuning A Quadrajet?
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Joined: Apr 2002
Posts: 91
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From: Asheville NC
Tuning A Quadrajet?
Does anyone know how to properly "tune" a Qjet? I have a book on rebuilding and adjusting and the only thing it says about adjusting mixture is for the feedback model (which mine ain't). How can you tell when your mixture is right? Is there any good starting point for the adjustments? I feel that my engine is lacking power and I'm wondering if this is the cause. :confused: :confused:
Drifting
Joined: Jan 2002
Posts: 1,645
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From: Schaumburg IL
Re: Tuning A Quadrajet? (JoeMacgruder)
Before you jump at the carb, do a complete tuneup if you have not done so. Check the timing and make sure your initial, centrifgual and vacuum are all right on. Hook up a vacuum gauge to manifold vacuum and see what you are pulling. A stock engine should pull betwen 16-18" at idle. Jab it and see what the needle does to check out the overall condition. Record your readings. The repair manuals have some writeups on using one. If need one they are cheap and come with instructions.
Check that the secondaries are opening. Open the throttle with the choke off, open the secondariy plates and see that they are open. Take some carb cleaner to the carb linkage and internally. Now see what the car runs like.
Check that the secondaries are opening. Open the throttle with the choke off, open the secondariy plates and see that they are open. Take some carb cleaner to the carb linkage and internally. Now see what the car runs like.
Pro
Joined: Jun 2001
Posts: 672
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From: Quebec
Re: Tuning A Quadrajet? (JoeMacgruder)
Hi, go to http://www.corvettefaq.com in the engine section, find the paper on how to tune the Quadrajet by Lars Grismuld. It explain very well how to do it. Lars is a Quadrajet God. I just did mine with it and the result is awesome.
For your idle mixture screw, the best way to adjust them is with a vacuum gauge. You have to unscrew them till you get the best vacuum reading. At that point, if you unscrew more, it won't change anything. Be sure to put the two screws at the same adjustement. When you unscrew them, let the engine about ten seconds to react. A good starting point is 2 turns back.
Happy tuning.
Stephan
For your idle mixture screw, the best way to adjust them is with a vacuum gauge. You have to unscrew them till you get the best vacuum reading. At that point, if you unscrew more, it won't change anything. Be sure to put the two screws at the same adjustement. When you unscrew them, let the engine about ten seconds to react. A good starting point is 2 turns back.
Happy tuning.
Stephan
