The Secret Behind Quadrajet Carburetor: How it Works

The Quadrajet carb has somewhat of a bad reputation in the classic car hobby and it is harder to tune than one of the many performance types of carbs. Still, in it's stock form the Quadrajet can be a reliable and decent performing carb as long as it is maintained. For the type of driving I do with my Corvette, the Quadrajet provides adequate performance and decent fuel economy.

[DougsMessyGarage]

I'm no expert but I have worked on these carbs a few times over the years. Feel free to ask me a questions if I didn't explain something in the video.

[robertwest]

The Quadrajet carburetor is and will always be my first choice on a street engine. I’ve even used them on small block Fords before. They love them!

[RedfishCarolina]

Had two of these I think, both were on Olds 307's (85 Riviera and 85 Cutlass Supreme). Never had a problem with either of them.

[ericschrock]

Zero mechanical experience here so I appreciate the video! Working on one from a 72 Deville. Hard to really get into it when I don't even understand the theory of operation. Thanks for the run through!

[Inthefoxhole]

I've built holleys and Quadrajets.If you want a good reliable carb with not much maintenance. Quadrajet is the way to go.I had a 73 chevy van 350 engine.350 turbo trans.373 gear Fastest van around.I ran 650 holley double pumper.Didn't perform anywhere near that Q jet in that application. I'm putting float well plugs in my Q jet as I speak.

[setha]

Always check the butterfly brass bushings by moving them up down for wear, Im currently waiting on bushings and remmer at the moment when bad they let air in and cause rough idling to lean condition.

[snowcrest]

Not an ideal carburetor for performance tuning, but when it comes to daily driving (back-in-the-day) it was the best for basic starting and driving. Many times growing up in Minnesota, the old '74 Impala Wagon fired right up at -20 below zero. When GM/Chevy came out with their first generation fuel injection in the early '80s, none of those cars would start below 0 F.

[danlaabs]

Some rebuilders say to remove the hanger off the needle so it seals to prevent back flow.

[willytv]

Question - why is the linkage from the diaphragm connected to the slotted lever arm on the secondary butterflies? I thought this lever was just associated with the choke.

[randyweitzel]

Great videos, my 1987 monte ss 305 was rebuilt. Gas mileage is way down 10 miles per gallon from 17. What can I check. Maybe the primary metering rods need adjustment?

[randyweitzel]

Ok I'll see if a friend can help on your advice, thank you. Do you rebuild carburetors ?

[Batman]

My secondaries ain't opening up going up hill or when I hit the pedal. I can't figure it out what would be the reason for that please and thank you .

[jtp]

good video! I need some advice on something. I recently bought an 1986 chevy truck with a V6 4.3. It has a propane system on it and the original carburetor is nowhere to be found. I have a 78 quadrajet that I just rebuilt and would like to install it. the truck intake manifold is the original spread bore quadrajet carburetor. Also this engine has the electronic spark control distributor without the vaccum advance. if I put this 78 carb I got on it do you think it will work just fine?

[josephsabia]

What would cause the secondary lockout to stay engaged when the engine is warmed up to operating temp? We’re having a problem getting the secondaries to open up

[gabrielbryant]

What I needed to know was how to adjust the air and fuel man

[buffordevans]

When giving this carb throttle should a jet of fuel be seen on both sides of the primary or just the side where the pump is ?

[tomsteffs]

what would cause a high idle upon start up and violent dieseling upon shut down of the motor?

[dennistrahan]

You have NO idea how to properly disable a Q jet my freind, you ALWAYS remove the roll pin from the accelerator pump arm and the secondary metering rods before attempting to lift the airhorn top of the carb from the midbody so you don't BEND THE METERING RODS AND TUBES !!! thats why you fond the tube laying in the midbody of the carb !!! Heat has no bearing on these tubes falling out !!!
Ive built hundreds of these carbs since the early 70's, NEVER have I twisted the top sideways to unload the acceleration pump lever to remove top of carb !
Dennis Trahan master technician 52 yrs experience experience .

[xkaosxvpx]

If gas can be sucked into the line but doesn’t make its way into the carburetor, what could be the issue? Thanks.

[inell]

So did you end up selling this car? Don't see anymore videos.