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
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.
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.
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
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.
Edelbrock Foundries and Manufacturing
Edelbrock produces all of our cast items right here in the USA at our two
state of the art foundries. You can be assured that when you are purchasing
an edelbrock casting it is the best quality available. Check it out from
start to finish.
How to adjust Quadrajet/Dualjet fast idle
Quadrajet/Dualjet Rochesters have a fast idle adjustment screw that is
separate from the base idle screw.Here's how to locate it.
NOTE THAT THE CHOKE ITSELF MUST BE WORKING IN ORDER FOR THE FAST IDLE TO
how to minimize engine bog with a Quadrajet carb
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.