July 2009 ======================================================================== /////I would like to replace the Q-jet on my 78 with something newer. Does anyone have any recommendations if there is such an animal without changing the manifold? Over the 24 years of ownership, it has been rebuilt twice. I am going to replace some of the original engine parts like the water pump and fuel pump just to freshen things up, might as well do the carb as well. Any recommendations on those as well? Thanks, B.C. //// ======================================================================== Holley makes a spread bore Q-Jet replacement and Edelbrock did at one time make a Quadrajet clone. If your carb isn't giving you problems you might not gain anything at all by replacing it. They 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 R2R5388 ======================================================================== 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. As far as water pumps or fuel pumps, why change them if they're not causing you any trouble? If you really want to change them, there are three different small block Chevy water pumps...long, short and Corvette. You need to determine which you have or the pulleys won't line up (I'm guessing your engine has the short). There are many quality water pumps available from companies like Edelbrock, Moroso, Milodon and others. Edelbrock, Holley, as well as Summit and Jegs sell fuel pumps. If you do that, get one that has a housing that can be clocked, so fuel lines can be easily lined up. Bruce Blum ======================================================================== 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. chuck RQB-3553 ======================================================================== 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. JohnA ======================================================================== I agree. I only brought up the Holley spread-bore as it was a direct bolt-on replacement for the Qjet and about the only alternative without changing intakes. The Edelbrock Performer carbs are excellent carbs...easy to adjust and they hold their adjustments. They are a better street carb than Holley or Demon. I still believe the Qjet is the better way to go without changing intakes. Bruce Blum ======================================================================== 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. Ernie R2 R5388 ======================================================================== I am running the Edelbrock 1406 with the jetting that it came with. The factory put 101's in the front and 89's in the back on the AFB. I tried 100's in the front and got a good puff of black smoke in warm weather. Every engine is a little different and my compression may be a little lower than stock so leaner may work for me. Each Edelbrock Carb has different jet sizes what series are you working with? Ernie R2 R5388 ======================================================================== Thanks for all the good information, its great to be able to ask and recieve such good stuff.?? I drive my 78 every other week or so, and the only issue I have had with the Q-jet is that it seems the float sticks occasionaly, and floods on the first start after sitting for the week. (fuel pouring out of the carb all over the manifold).? This is not a good situation for sure.? A good whack on?the carb housing settles things down.??I?have had the carb off?several times, but not been able to find the cause for?this problem.? ?As per your information, I looked up Jegs and Summit, and they both offer reman. Q-jets for $300.??? Bill Chapo RQB 2677 ======================================================================== It's been some years since I worked in an auto repair shop, but the experience I had then was assembly line rebuilt carburetors had a horrendous defect rate. I know Summit and Jegs are very reputable and would likely have quality control taken care of, but even if the carbs were rebuilt properly, the fact remains they are generic rebuilds and may not be jetted properly for your specific application. That creates a situation where your new carb may still not be set up properly for your car and still requires shop work. I would suggest you have your carburetor rebuilt by a competent shop. The rebuild shop local to me is very good an their carb guy told me several years ago that unless a carburetor is physically damaged there's no reason it cannot be rebuilt rather than replaced. Unless your engine has had changes to the heads or cam, you're already jetted properly. Bruce Blum