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Decoding a Rochester Quadrajet part 1: The name

Rochester Quadrajets tend to mystify people because of the various model names assigned to them by GM. Add to that a redesign in the '70s and the confusion only grows. In this video we'll learn the different model names and also how to differentiate between early and later-model Qjets. Enjoy!


 


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Decoding a Rochester Quadrajet part 2: Breaking down the numbers
In this clip we'll learn how to decipher the Identification number and julian date code on the Rochester Quadrajet.





How to adjust Quadrajet secondary air doors
These take some trial and error to get them adjusted so that there is no bog, but it's not hard to do-here's how.





How to de-bog your Quadrajet part 2
The Rochester Quadrajet has gotten a bad rap over the years, but it's actually an excellent carburetor once you understand how they work. Often referred to as "Quadrabog" or "Quadrajunk", many of the issues these units suffer stem from neglect, or "modifications" that do more harm than good. Being a spreadbore, air-valve secondary design, the Quadrajet is capable of flowing 750 or 800 cfm of airflow, eliminating the need to buy different carburetors when your set-up changes. In addition, the small primaries make for great drivability and fuel economy. In this clip, I'll discuss theory of operation on the secondary side, since that's where most problems arise. So, leave your preconceived notions at the door and let's see what makes these carburetors tick.





Adjusting High Idle on a 4 Barrel Rochester
Adjusting the high idle on a 4 barrel Rochester Carburetor.





'77 Chevy K20: Quadrajet Choke Pull Off and Fast Idle Cam Observations
1977 Chevy K20. 350 crate engine. Rochester Quadrajet 4MV carburetor with divorced choke. Truck suffers from unexplained hesitation and bogging when in forward gears. Tends to rev just fine after a few minutes of mixed idling and high revving. Checking choke operations as well as a possible sticky fast idle cam as part of the process of elimination. - Truck is allowed to idle/warm up until 2:25 mark, at which point the engine is revved to about 2,000 rpm, and can be heard bogging (a hissing sound can be heard). The fast idle cam is seen dropping. Fuel flow can be seen in the glass-cased fuel filter right before the carb as remaining steady. - The engine is revved again about three more time up until 3:00 minute mark. The engine revs slightly higher, but the hissing and bogging can still be heard. - Engine is revved again at the 3:35 mark, slightly past the 3,000 rpm mark. Hesitation and hissing still evident, but less so than before. - Engine revved at the 4:25 mark to about 4,000 rpm. No hesitation or hissing heard. - Transmission is slowly shift through every gear starting at 4:55 mark. Shifted back into Park at 5:05 mark. - Engine revved again at 5:10 and 5:17 marks to 4,000 rpm. No hesitation or hissing is heard. To read up on the discussion, please visit the following thread: http://www.hotrodders.com/forum/1977-chevy-k20-engine-suffers-hesitation-po wer-loss-when-drive-213757.html





How to rebuild a Rochester Quadrajet part 5





750 vs. 800cfm Rochester Quadrajets-how to tell them apart
There exists a ton of misinformation regarding the actual airflow capacity of the Rochester Quadrajet. Not many people know how many variations there are or how to tell them apart. Here is a simple video explaining how to identify each size based on casting design. I will cover the "cfm-limited" carbs in a separate video.





Quadrajet Electronic Carburetor Rebuild - Teardown Part 1
http://www.carburetor-parts.com. Mike's Carburetor Parts has provided this video about the Rochester Quadrajet, electronic version. Part 1 of the tear down video.





1984 Chevy K20 50 to 70 mph
Punch it! I love to ear those secondaries open up on a four barrel carb. This truck reminds me of the sounds used in a lot of 80's tv shows and movies with car chases. I love it!





How to identify 4 barrel carburetors
Here's a guide to help identify the most common 4bbl carbs including Edelbrock, Quadrajet, Holley and Thermoquad. There are a few older or more obsolete carbs not shown including Rochester 4G, Autolite-Motorcraft 4100/4300/4350 and Carter WCFB that I'll detail in the future provided I can actually find one.





How to rebuild a Rochester Quadrajet part 8





Everything you wanted to know about automatic chokes but were afraid to ask pt3
I've noticed many people drive vehicles with inoperative chokes. Even though chokes can be intimidating, repairing and adjusting them actually is very simple. So, stop pumping that accelerator and follow along as we look at how chokes work and how to repair them.





How to measure and adjust Quadrajet float level
I have had several requests for this, so here you go: 1. The airhorn has to be removed to do this, but the carburetor does not have to be removed from the engine. 2. Some data says to measure from the toe(end that is opposite from the hinge), some say 5/16 inward from the end, etc. I suggest following the specs for your particular carburetor. 3. With the float in the raised position and the inlet needle lightly seated, measure from the top of the float to the top edge of the carburetor with NO gasket in place. If you have to adjust the float, bend at the area that has the cutouts, 4, If you are experiencing flooding issues then it is an excellent time to install a new needle/seat and float and that should cure flooding problems that are not choke-related.





How to rebuild a Rochestor Quadrajet part 1
Introduction and beginning the disassembly process





How to rebuild a Rochester Quadrajet part 9




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