Thanks to the Hamb, I was just edjabacated with the fact that the smallest Quadrojet made was a 750 cfm, and some where 800. Not knowing they were tyhant large, and literally having 6 of them that work in a crate in my basement, I want to know is there any way to choke out some of that fuel without replacing internals? In other words, can you turn the carb down from outside locations? Prob not, right? Curious? Pork
Pork As long as you are open to ejumakat'n, you do know that cfm numbers relate to airflow. All the questions you will ever need answered here. https://books.google.com/books/abou...ad.html?id=lThCgk-YSbQC&source=kp_cover&hl=en
The primary throttle blades of the carb are actually smaller than most 2 barrels that I've seen and worked on. So as long as you're not into the secondaries, the engine is seeing a very small carb. That's one of the plusses of Quadrajets.
My understanding of Qjets is that it will flow UP TO 750. Just look at the primaries, they are small and thats what you run on until you stomp on it, then those huge secondaries will open and it will flow whatever it needs. Someone will correct me if I am wrong.
Don't worry about it. As long as everything is working right when the secondary opens it will only feed what the engine wants. Around town enjoy those tiny primaries. -Dave
if you want to identify what they are off off the numbers are on the driverside rear screw stantion it a begins with a 705 , 1705 or 1708 number its a stamped number not cast and runs verticle and with them you can cross it over to year ,and make , and then do some digging and find which vehicle they grouped it to ( the letter codes sometimes tell you that also any specials like a high altitude carb ( real lean jetting ) . one easy way t identify the BOP from the chevy s are , the BOP the fuel inlet comes in straight , the chevy comes in from the right side , and the bell crank on the accellerator linkage on a chevy most of them are C shaped . and unless you are putting a 454 truck or 455 big car carb on a 265 or 301 jetting is not a worry the primarys are only 250cfm on the little ones and 300 on the 800 models .
Might want to read up on basic carburetor theory....carbs don't provide any more fuel than the engine needs, and how much it needs depends on how much air is flowing through it. And you can control the airflow by not opening the throttle so far, and it also depends on how fast the engine is turning, as well as how big the engine is, etc. Some engines like a Quadrajet, some don't work so well with them. Stock or mildly modified engines from about 250-500 cubic inches are good candidates.
So now to further extend my sounding foolish, what are the screws down at the base and on the sides for? I understand that one or two are related to idle and choke.but do do any deal with thinning or increasing air or fuel?
In addition to the Ruggles book you may find these links useful: http://www.vetteprojects.com/kstyer/quadrajet.htm http://www.generationhighoutput.com/Quadrajet_Service_1981.pdf
nope just idle mixture and throttle opening ( can adjust the speed and some mixture by opening the blades ) we do reccomend you might want to look into the Rochester book by Doug Roe , it will show you how they work internally and how to fine tune them for more performance and milage . and tells you what arts you can and cannot use ( they do have some internal differences on some items ) best 25 bucks you can spend ( mines from one of the first printings in 1986 )
oh you have the green cover book , the revised copy ( black cover and covers apt . egr , emissons and CCC ) which is the one I have was 86 as I had to wait for it to be printed ...
I wanted a copy of the green one , but never could find it as it was out of print for several years . and then when I met Doug thru a friend of mine he told me the "new "book covered it all but IIRC that book was twice as thick .
the new book is about a 1/2" , I thought found a used copy of the green one but the person was using a picture of it to sell a revised edition ,
The Jalopy Journal
