Quadrajet notes. ( compilation of AOAI chat forum exchanges - 2009) ----------------------------------------------------------------------------------- If your car came with a Quadrajet, it should be (worked on) by a qualified rebuilder. Quadrajets are one of the best street carbs ever made but require someone who understands them. The Quadrajet is an excellent carburetor...particularly for a street car. If you can get your Qjet rebuilt by someone who knows what they're doing and can set it up correctly for your engine, that would be the best way to go. If you're compelled to get a different carburetor, you'll need a spread bore carb or it won't match up to the intake manifold without an adapter, which can lead to hood clearance issues. Holley makes a carburetor which is a direct, bolt-on replacement for the Qjet (Holley part #6210). Summit Racing and Jegs should carry it. If your engine has an EGR valve, it may not clear and you can either eliminate it or get an adapter that moves the EGR out of the way (they are available as well). If your car has a/c, you'll probably need the appropriate Holley a/c kick-up solenoid as the GM solenoid may not be compatible. Your other option is to install a new intake along with a carburetor. That will give you a much larger field of choices in intake/carb setups, but you said you want to avoid that. If you decide to go that way, my suggestion would be an Edelbrock Performer EPS intake with an Edelbrock Performer 1406 carburetor. Again...it would need the appropriate Edelbrock a/c kick-up solenoid. Bruce Blum ----------------------------------------------------------------------------------- On top of the Q-Jet there is a electric plug going into the front, that's the M/C solenoid it's controlled by the ECM Once the car is warm, pull that plug idle should change. Sometimes, if the lock tab has been broken off the plug can be installed upside down, see if that's the case, pull it and see if it changes something installed the other way if the clip is gone. Normally, if there is a problem there it would trigger the "Service Light". Whenever I had a car with a quadrajet I checked 2 things right away. One, make sure your throttle linkage is opening it up all the way. Most I've seen even right off the assembly line could use a little adjustment. Two, with the engine fully warmed push down on the back of the air valve covering the secondaries. It should open with a little effort. If it doesn't it's probably because the linkage that keeps it from opening until the choke is completely open needs a little adjusting. There's a little tang that covers the valve until the choke opens all the way and pulls the tang clear. It only has to be off a little bit to keep that valve from opening. If the valve doesn't open you have a 4 barrel that is working like a 2 barrel. There are only two things I can think of that would cause that (flooding)...bad needle and seat or a float linkage issue that causes the float to stick after it drops past a certan point. When the car is running there is fuel in the bowl that keeps it up past the sticking point but when the car sits fuel evaporates allowing the float to drop lower than normal running levels. There is usually a float hieght and float drop setting. Sounds like float drop is wrong on your carb. There is a cam that has it's own adjustment screw, if memory serves on the side. It should be activated by a rod connected somewhere to the choke. The rod could be on wrong or have come off and I think the adjustment screw is hidden a bit below the choke thermostat. They (Quadrajets) are fairly large CFM 750, the small bore primaries are great for part throttle acceleration and if the air valve over the secondaries is adjusted properly you get bog free full throttle acceleration. Ernie Ernie Rizzolo ----------------------------------------------------------------------------------- The floats should have a tang on them to prevent them from dropping too far. You should be able to adjust the float drop per the specs.This will probably correct the problem. Charlie Kile RQB3821 ----------------------------------------------------------------------------------- The Quadrajet is a very good carb that is hard to beat when setup right. I have two vehicles with them, the Avanti and a 78 Chevy pickup (I have owned it for 27 years and the same Quad on two different engines continues to provide troublefree performance). There is little that goes wrong with them. The biggest issue is the foam floats-they absorb gas over the years and you end up running rich. Replacements cost around $10 and fix most problems with a Quad. Put new floats in every 8-10 years and your Chevy small block should run smoothly. There is no other carb that produces the sound of those big secondaries opening when you let your motor rev under load. If it has a foam float (looks like black plastic) it could be saturated. Then it won't generate enough force to hold the needle closed. If a foam float is more than 10 years old it will have absorbed some amount of gas and it will be heavier than it should be. This is a very common problem on Quadrajets on Chevy motors. Replace the foam floats first. It's cheap and pretty easy to do-you don't even have to take the carb off the engine if you don't want to. This should cure your overflowing. QJet floats are only good for 5-8 years, especially in low use cars. After they absorb gas, they don't float so well and they get larger in size-could be the cause of the sticking. I hate to tell you the number of carb equipped cars I have fixed after the owners spend a lot of bucks on other fixes. Chuck Paras ----------------------------------------------------------------------------------- I would check and see if NAPA has brass floats instead of the closed cell foam floats for the Q-jet. The price difference is generally $10-12 for the closed cell foam and $25 for the brass. I don't like to plan to replace the floats if I can avoid it. I've rebuilt several Q-jets with excellent success. I'm not discounting I may have problems with my next one, but I do believe they are very rebuildable with a quality fuel system mechanic. :-) Del Compton ----------------------------------------------------------------------------------- I made the mistake of replacing my qjet with the Holley spread bore.? If you do some research you find many opinions on it being a poor carb.? The Holly carbs are difficult to set and are very sensitive to ANY dirt that getds in them.? The spreadbore is actually a poor carb and as many stated, never should have been made.? They saw a market when Edelbrock stopped making? their spread bore and made it to for that market but it is one of their poorer products.? As others are telling you, the Qjet is a great carb and you would be better of getting a rebuilt one from a carb shop or getting yours rebuilt.? Your other choice is the edelbrock with an edelbrock intake manifold.? The manifold you can find on E-bay for a very reasonable price.? The Edelbrock carb is much easier to tune and adjust since jets can be changed without taking it apart.? The Holley is for guys for like to tinker with their car all the time. John AAndras