The last thing to be looked at on the wagon, but really, no old car project is ever done, things keep being played with and adjusted. This is a correct Rochester Quadrajet 4-barrel carburetor I got some time ago, and has been renewed with new seals. The bushings and other hard parts were in good repair, so with the new seals. T o note, I called out the first three serial numbers as being "701" when in fact it starts with "704" . When building up a Rochester, one has to understand they can't just throw parts into it, they may be unhappy with the results. They should also be ready to have to change a jet here, a metering rod there, a spring or two after the unit is on to get the car running perfectly. The Quadrajet is a sweet carburetor, once you understand it a bit. As I am doing. It is running well, but will need a bit more tuning in the way of a stiffer primary metering rod return spring. Other then that, the car has more bottom and top end power, mid range is the same, but the bonus is, fuel mileage has picked up, the leaky bowl of the old unit is gone!
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.
Quadrajet Electronic Carburetor Rebuild - Teardown Part 2
http://www.carburetor-parts.com. Mike's Carburetor Parts has provided this video about rebuilding the Rochester Quadrajet E4MC, E4ME, electronic version. This video is part 2 of 2, tear down. A later video will feature the assembly of this carburetor. (c) www.carburetor-parts.com
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.
More Quadrajet tuning, some things! Part two in this Saga Sept 13, 2010
With the camera sitting on the oil filler cap a few more things to show how a metering rod system works on a carburetor. The car has a slight stumble and surge at a light throttle cruise at about 55 to 60 MPH. By swapping out the .050 metering rods to .048 units, the stumble and driveability concerns are now gone. Going richer would mean worse fuel mileage one may think? No! Now that the mixture is right, LESS throttle opening is needed now, which means higher vacuum, and this way the metering rods will block off the correct amount of fuel, and in the proper timing and percentages, so the car runs much smoother. As stated many times, patience and reading up on, and understanding how these intricate carburetors work will help out very much! Enjoy!
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 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.