this is to minimize engine bog when the pedal is to the metal. do not over tighten, very small spring...you want to try 1/4 turns or 1/2...q-jets are good if tuned properly. also when you are tightening screw it will have tension on it so keep the screwdriver firm. 1986 gmc sierra single straightpipe to cherrybomb. you will need a small flathead screwdriver and a 3/32 allen key. be sure not to tighten to much or else your vacuum secondary flaps wont open.
How to de-bog your Quadrajet part 1
Sorry guys, I got the videos a bit out of order.
The Rochester Quadrajet has gotten a bad rap over the years, often called a
Quadrabog or Quadrajunk.
In fact, this is a great multipurpose carbureter once you understand how
they work and what not to do to them.
In this clip I introduce you to the Quadrajet and begin explaining the
theory of operation of these units.
How to debog your Quadrajet part 3
In the first two videos we looked at operational theory of the Quadrajet.
In this episode we'll explore a couple mistakes the home mechanic often
makes in an effort to improve the performance of this unit.
See 1976 Chevrolet pickup with Rochester quadrajet upgrade on SBC 350 V8.
We removed the hood, mounted a camera looking down on the air horn, and
took it for a spin, running wide open on an uphill grade. See how the
secondary air valve responds to rpm drop at each upshift of the THM. Also
included is a smoking burnout.
How to adjust carburetor mixture screws
Here's how to find and adjust the mixture screws on your carburetor.
Note that metering-block style carbs such as Holley and Demon more often
have one or 2 mixture screws in each metering block depending on the number
of venturi. Also those may not be located at the bottom of the carb as in
Identifying Quadrajet vacuum ports
I always see a lot of questions about what various vacuum ports do on a
Here's a general guide that will point you in the right direction.
Remember that there were many different Qjets over the years and vacuum
port locations and number will vary. This video is representative of
Quadrajet air leak fix and warped air horn repair tutorial.
How to identify a Quadrajet with a warped air horn without diss assembly or
running it on a car. These tips would have saved me time and money which is
why I made this video. I also discus how to repair a warped air horn and
prevent your air horn from warping in the first place. If you have a
whistling noise just off idle then you got some work to do. You will never
get your engine tuned right, your cold start performing or decent fuel
economy unless your four barrel carburetor is just right. Special thanks to
Cliff Ruggles for his book Rochester Quadrajet carburetors and to my
brother Adrian who spent hours on tuning and fitting.
See this video for description of the technique I used to straighten a
warped air horn.
here is a technique for re-bushing the throttle shaft without drilling.
Setting the timing and adjusting the carb
Set the timing by ear, and got the idle slowed down so I could do a little
adjusting on the carb. I'll do more when it's cold, so I can set the
choke and all. Love the way it's sounding..
Setting Curb Idle Speed of Carburetor Video -Holley Carb DVD
Buy the "Holley Installation & Tuning" DVD
Holley Installation & Tuning DVD: Curb Idle Speed Screw
Here we show you how to properly adjust the curb idle speed on your Holley
carb. First find your idle RPM setting from under your hood or from a
repair manual. Turning the screw clockwise will raise the RPM's and counter
clockwise will lower the RPM's. Check and adjust until the proper setting
If you buy a brand new Holley 4-barrel, this DVD now comes in the box with
every purchase. If you already own a Holley carburetor or would like to
learn about the internals of the all-time, most popular modular style
carburetor, this is the DVD for you.
It's the ultimate installation, tuning and troubleshooting guide for the
Holley modular style carburetor. This disc will also help tune and
troubleshoot any other brand of modular style and some one-piece style
Menus are full of bonus information and detailed animated tours of
internals and accessory kits.
Get the full DVD with all of the interactive menus, detailed animated tours
of internals and accessory kits here...
Don't forget our Basic Engine Building DVD. This video is great for people
interested in car repair, car care, and restoration. As well as hot rods,
muscle cars, performance parts, and Boosting horsepower. It can also help
you to gain knowledge for increasing fuel economy, how to lower your
emissions, and covers preventative maintenance to avoid little things like
Sample clips on our YouTube page and at our store here...
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3 New Transmission DVDs and a Differential Rebuilding DVD just added.
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