Review Of The Rochester Quadrajet - The Most Common 4 Barrel On Earth 

The Rochester QuadraJet is the greatest carb ever made. The fact that I'm a lifelong resident of Rochester and live maybe 10 miles from where they were made has nothing...NOTHING...to do with it 🤣

As VGG once said. The people who don't like Quadrojets don't know how to tune them.

The Qjet. Hated by millions who never had a Qjet set up correctly. Hearing the four barrel working through functional arm air is muscle car bliss.

Rebuilt hundreds of " Quadrajunks " during my 49 year wrench career . About their only real problem was often overlooked - the wallowed out primary shaft hole in the throttle plate creating huge vacuum loss . Aftermarket bushings were a simple fix .

Very reliable carburetor. No 4 BBL sounds better kicking the secondaries in !

my buddy had 85 monte carlo SS and yes I know it did not have lot horsepower compare to today cars but when the four barrel open is when the magic happened. Brings back great memories of late 80's . Thanks

Worked at a cad/ olds dealership had an old mechanic that replaced several a week! I snagged everyone I could pulled apart, had all sizes of jets, metering rods primary and sec. Different power valve springs ! Loved the carb in a 350 I built in a 3/4 ton pickup never a bog or stumble start to a pegged speedo. Lot of part switching at first but boy did it work great. Thanks Tony. God Bless.

Quadrajet, the finest carburetor ever made. The haters don't understand how to tune them, and that will make you hate it.

The biggest problem with the Quadrajet for hot rodders is that each one was factory tailored to whatever application it was going on. Engine displacement, auto or manual transmission, sea level or high altitude, all of these parameters were factory set and you have to really dig in and sometimes make permanent modifications to get it tuned properly for a non-factory application. Once you learn how to do it there's no turning back.

The best thing about a Q-jet was that they always worked. As long as you kept them clean, they were trouble free.

As a life long fan of the Q jet I must confess my sins here. I have plugged those two holes that Tony mentioned with Bazooka joe bubble gum. I was just trying to get back on the road and drove on that carb for 5 or 6 months before selling the car. 2 owners later it got a Holley because that kid thought it was an upgrade. I should have bought that Q jet back.

The adjustability and the ease of maintenance on the QJ are its strong points.... along with great part throttle fuel atomization. As stated, the fuel bowl area leaves a lot to be desired, but on a small-cubic inch V8, these things were amazing. Lots of torque, great throttle response and, when the urge to pass somebody hit your right foot, they got up and flew. Great review!

I started working on cars at a GM dealership right out of high school in 1995. We used to rebuild these all the time. They were still very common on the road in the mid 90’s. I would say at least one a week average. The well plugs were VERY common issue we seen.

Cliff's High Performance is a great resource for Qjet building for the average hot rodder. If you call them you can likely speak to Cliff himself and he can give you a reasonable guess as to what rod and jet size you'll need, as well as how to drill out the idle passages to "resize" a Qjet for a higher performance application (making a factory 305 carb idle properly on top of a hot rodded 350 or 403 for example)

I had boxes of these years ago, I learned a lot of the tricks to them and with several tweaks and small modifications I had very good results from them. The most misunderstood thing was one you learned how to work with them, they remained set, whereas Holleys you had to fart with anytime the conditions changed. They could actually be very hot carbs once you figured them out.

I rebuilt one. First time for a 1968 Toronado. Followed the instruction sheet and that car ran like a champ. Even the choke was perfect. Great carb.

I had one off a Cadillac 500 on my 11 to 1 purple cam 440. Ran awesome excellent throttle response and gobs of power. No adjustments just bolted it on.

My buddy used to rebuild these for fun. He would buy them from salvage yards and rebuild them, then put them on his shelf. His dad taught him the tricks to them. He put them on all of his vehicles. My favorite ones were on his 455 Buick, and 455 olds. The sound they made was awesome. Sounded like the hood was going to be sucked into the motor. The memories of that sound as he rolled past 5.0 mustangs with his 850 cfm sounding off will always be with me. I always considered them to be the 1911 of the carburators. To many parts for the average Joe to break down and rebuild, but incredible anyway..

My 1973 Pontiac 400 had a phenolic spacer under the carby and never had vapor lock. The Quadrajet is the center of the famous story of the Pontiac that hated vanilla ice cream. A classic.

The QuadraJet is without a doubt an excellent carb. They do make strip kits for them, and the fuel delivery issue as a result of the incredibly small bowl can be helped by what you mentioned; different size/shape floats, bowl contouring, as well as larger orifice seats, and windowed seats. I ran deep 11s with a 69 Nova street car, very mild pump gas 454 and a 4-speed, with a HV pump, and a larger/windowed needle/seat. Never nosed over once, and was as responsive as EFI I also have over 2 dozen Thermoquads in my “collection”, most of them being the early 6xxx series, and two aftermarket SuperQuads. All are excellent carbs. 👍

1990 was the last year of the quadrajet... on an olds 307 in a 1990 olds custom cruiser wagon, albit it was an electronically controlled quadrajet

Love the dog doing laps around the house!

To think the quadrajet has been “out” of production longer than its entire run of 21 years lol… man time flys! Still the best street carb.. especially when it comes to weather up in Canada where I’m from.. still use a edelbrock rpm 1910 quadrajet on my big block 67 Chevelle, got sick of sticking floats, crappy gas mileage in the Holley’s not to mention the constant tuning whenever the temp started changing!

Q-Jet first used on the new for 1965 L35 396/325hp V8. 1966 saw an expansion across the GM lines, but not full use.

Never had a problem with the Quadrajet aka the “QuadraJunk”.Great cruising carb when tuned right

I used to love it after a rebuild when the owner drove it for the first time…I’d set it up so the secondaries and the downshift hit at the same time. A strong stock engine could bark the tires. Saw a LOT of really wide eyes!

There were a few quadrajets in 1965, they were on most GM four barrel engines in 1966.The last was a 1990 Olds 307. Carter also made some quadrajets for GM. They look identical to the Rochester.

Got my father in laws 76 Ramcharger, equipped with a quadrajet, running today after sitting 10 years. Runs like the day it was parked.

Quadrajet is poor man's fuel injection. My K5s love them! I was stuck in a hole at 45°, and the quadrajet didn't miss a lick for an hour until I got the winch to reach something that would hold.

Tony: On February 15, 1967 my father took delivery of new Pontiac Catalina. Stalling issues were addressed by Allison Pontiac, RIP, with the warning not to use "Shell" gasoline. The problem, as you indicated, faded away. Thanks, for the trip down memory lane.

I'm not a carburetor guy but I love the sound of a flipped lid quadrajet when the secondaries open up.

One of the things that separates the Q-jet from other carbs is the off-idle circuit. All other carbs only have idle, main, and four barrel. The Q-jet offers a fourth circuit...idle, off idle, main, and four barrel. Another known problem that old Q-jets have is worn throttle shaft. A worn throttle shaft causes vacuum leaks, and the throttle primaries to hang up.

I am an off road guy. What I can tell you is the Q jet is hands down the best off road carb out there. The reason it works so well is the exact reason UTG cites as a disadvantage. That is, it's small float bowl. When you are off throttle, even a small amount of gas spilling into the manifold would kill the engine. Off camber would starve the engine. Imagine moving down a steep, ruff incline at idle. With a Holly and it's comparatively gianormus float bowls gas can just spill through the main jets, put the fire out in a heartbeat. On throttle on woops you could hear the engine sputter and the tell-tale puff of black smoke. Holly recognized the problem and made accessories, which I dutifully installed, but never really solved the problem. Power brakes and steering are compromised at the worst possible moment. I rolled my jeep onto its roof and my Q-Jet was STILL RUNNING. I actually had to reach up and turn off the ignition. Loved the Q-Jet, next best thing to Fuel Injection, which is what I have now.

GM ran em for decades for a reason. Most reliable carb ever made.

I have a 1972 C10 Pickup which had its original 350 engine with the QJet 4bbl carb. Over the last few years a knowledgeable friend who has built many Chevy engines built a 30 over 400 small block for me which will has about 325/350 HP and 400/425 ft lbs of torque. When starting the build I asked if we should get a Edelbrock carb, as the QJet has 91000 miles, for the new engine and he said no reason as the QJet is all we need and he was going to rebuild it which he did. He said people do not understand them and they are a great carb. My engine and the rebuilt QJet are working well together.

The sound of a 396 when the Quadrajet kicks wide open is unforgettable.

It was a dodge man many years ago who taught me how to rebuild and tune the quad. Once again a dodge man helping the Chevy people.

My camaro had an electronic Q-Jet from the factory. What an absolute pile. I swapped it with an earlier model. Picked up a book with tips and tricks for Q-jets, and proceeded to create the best running street carb I’ve ever owned. Since moved to Holley’s for performance, but still love a well tuned Q-Jet

Had one on my first car ever...man, what a sound it made after you flipped the air cleaner lid. Made a teenager grin ear to ear!

In Michigan we loved those carbs on our work trucks especially in the winter they always just worked.

The best street driving carbs i've ever owned were, and still are, quadrajets. One of mine has developed the well plug issue. a few years ago it was very slow and would only leak out over the course of a few days. Now it leaks down in less than a few hours. Need to pull it off and fix it. I should probably send it off and have it rebuild because it's leaking air through the throttle shaft. Guess even the great quadrajet isn't susceptible to age with this example being 43 years old without ever being rebuilt. I think a large contribution to their lack of prevalence in performance applications, in addition to bowl size, is the lack of quick tunability. Where on a holly you can change jets, power valves, float heights, etc. quickly and easily making tuning far easier for the aplication.

WOW, 4 years already! I thought I was watching a repeat video of one of or maybe the first video I ever watched from Uncle Tony! man time flies, but apparently backyards and camera angles don't because it looks exactly the same! LOL ♥️ BTW I love the quadrajet when it's dialed in and working properly even though it weighs a thousand pounds compared to other carburetors but nothing beats the sound of a quadrajet, when those secondaries open thats an iconic classic sound!

In Australia the automatic, air conditioned cars suffered from vapour locks (mostly in traffic) and they fitted a diffuser/separator in the fuel line directly before the inlet of fuel into the carby which had a smaller return line back to the tank.

The tiny, centrally located bowl is actually a pro when it comes to off-roading, and off-roaders still love it when they don’t have EFI. The Q-jet can operate at angles that would make most other carbs lean out on one side and drown on the other. I’m a bit ashamed that I’ve never a run a Q-jet on one of my own cars . I’ve got probably a dozen Thermoquads, though, and I really, really love those. We all know the weak spots of that one, but when it’s not abused with over-torqued bolts and incorrect jet well O-rings, it works wonders.

As an old guy coming back to a classic car, this was a terrific breakdown of the Quad-J. It was clear, simple and to-the-point, I have subscribed to your channel and look forward to digging into all of your tutorials, thanks Brother!! (currently resto-modding a '68 Impala Custom Coupe, wish me luck :D))

Never used a quadrajet, but I love the T-quad.

What I did to fix the vapor lock issue was I had to get more cool airflow into the engine compartment. 1981 GMC Vandura 3500 21ft class C motorhome. I struggled for nearly 2 years with what I thought was running out of gas. But one night at a huge car meet. I attempted a burnout (yeah in a motorhome) and suddenly my engine died. Everybody at the car meet (mostly younger people) had no clue what I did. I opened the hood, removed the fuel line and started cranking the engine. I had these kids watching in shock that I was making the engine run again. I also watched air bubbles going through the inline fuel filter. I realized that I was getting too much heat inside the engine compartment. Later on I was back at the shop where I was working. I borrowed the grinder with a cutoff wheel and I cut out a piece of metal nearly the size of a license plate out of the upper rad support to get more airflow. Immediately after that, I no longer had all that heat buildup and no more vapor lock issues.

TONY- Your good, you know what you know. You don't know what I know. Did you know the quadrajet air horns warp which drips gas at the booster and causes idle problems? This is because their made from pot metal, and I would take off the horn, beat it flat with a hammer, and even if cracked, it stopped dripping and ran much better. I did this often in twin engine race boats and cars. Other than that( cheap metal) they were efficient. THERMOQUADS (YOUR FAVES, RIGHT?) Were very expensive because they were made with AIRCRAFT grade aluminum, the phenolic resign bodies DID NOT WARP ( one time there was an engine fire due to a leak- the Thermoquad though in the fire, only needed the idle air bleeds cleaned up in the passenger side where the fire was- the phenolic body was fine to my surprise! NOTHING can be tuned to produce the best mileage AND power than the THERMOQUAD- and their VERY light too! I saw your video years back with a very tragic, highly abused vestige if a Thermoquad with impossibly rusted throttle plates and a phenolic body with a chunk out of it somehow! Can't speak to what the hell that thing went thru, but I have built MANY T-Quads without any such issues. Biggest problem was the primary jet wells epoxy letting go and leaking into the recessed area of the base/throttle plates, causing slow leakage that produced a rich idle- Marine Tex white epoxy kit fixed them permanently (JB weld would only last a few years or so). THREMOQUAD was the PINNACLE if carburetor development for COMBINED STREET/STRIP. We will see with the new Edelbrocks! (Which are based on the avs afb Carter earlier design than the T-Quads, competition and superquads. No other carb EVER had such small triple boosted primaries with giant secondary dumps on STOCK 850CFM. NOBODY. IF more people understood the T-Quad they would be fans. They were that good, but VERY expensive when new, again, the biggest quirk was the jet wells, which the Marine-Tex solved.

Tony I'm a huge Q jet fan. I love the way they drive on the street, the sound they make when they're floored, and the snap off the line those tiny pimarys create. Have you ever read Cliff Ruggles book it's actually really good about getting quadrajets set up for high performance. One thing that really worked for me was adding an electric fuel pump because the mechanical pump couldn't keep the bowl full at wide open throttle. Also Victor Reinz makes a thick gasket that actually helps keep a little bit of heat out of the carburetor. And they're actually application specific because I think there's two different gaskets for Quadra Jets and it has something to do with the little notch on the primaries. Also they redesigned the Quadrajet in like 71 or 72 when they went to that shorter Quadrajet. I wonder if that was something to try to fix all the vapor lock issues you were talking about. I don't know why but I could never get the Holley Spread Bores to feel as good as the real Q Jet they were always very soft off the line.

The Thermoquad on a 340 is great! And tuning the T-quad is as easy as an AFB. I love the metering rods especially the 3 step.

I'm in the pro Q-jet camp, I run late '70s chevy trucks, all with Q-jets. I like them for economy and low end throttle response, I almost never even open the secondaries on them. They were introduced in '65, then became widely used in '67. The bowl design, float and needle valve were refined in the late '60s to increase bowl capacity and to give the float more leverage since they had problems with the fuel pump overpowering the float and forcing the needle valve open. It was also around this time they started using extra thick base gaskets to try to reduce the heat getting to the fuel bowl for the problems you mentioned. You're absolutely right about a conspiracy to make gasoline less volatile around that time so it wouldn't evaporate so quickly, but it wasn't a conspiracy between GM and the refineries, it was done because of govt. pollution laws to reduce emissions... less fuel vapor polluting the air. It was also around this time they stopped making external bowl vents on carburetors, and shortly after they introduced charcoal canisters for fuel vapor storage (evaporative emissions systems) and stopped making vented fuel filler caps. Anyway, if you're having trouble with vapor lock on your Dodge truck, you're best bet is to just swap it to a thermoquad so you don't have to modify throttle linkage, etc... You probably already know that you can get a base gasket that helps insulate the fuel bowl (two designs, one is open under the fuel bowl, the other closes off the gap under the bowl) but they don't always work and may not work at all on a Dodge for all I know. I like to block off the exhaust crossover in the intake, that seems to help the most, but then you also have to convert to manual choke, which I prefer anyway. The older 4MV Q-jets (up to 1974 in cars and 1978 in trucks) are less prone to vapor locking than the "modified" M4MV Q-jets (1975 and up in cars and 1979 and up in trucks), but the later ones have much larger fuel bowls and more adjustments so the're better for performance.

The 1986 k20 suburban I grew up in had a quadrajet, it was replaced with holley pro-jection, and put back on because the holley ECUs wouldn't last. My dad claimed that when properly tuned there was a 1 or 2 mpg difference between the q-jet and fuel injection.

I think they hung out to 1990 on some 307cu in. but Tony is right on with his observations. To some degree people love what they are familiar with. I like the Q-jet, I know it. No component is perfect but those are as reliable as anything made and have good throttle response. Everything is made with a purpose you just decide what fits yours. But now Uncle Tony, I want you to hot rod one and show us all how it turns out!

Being a young 20 year old car freak myself, it's so nice to see some love for this carburetor, the quadrajet and thermoquad will always be my 2 favorite carbs just because of that sound. The sheer tunability of the Q-Jet puts any fancy holley to shame, I've been wanting to get myself a small car to swap a 350 into with this carb

"CHOO-WAAH"...my rendition of the Q-Jet secondaries kicking in. The phenolic bowl float had a habit of gaining weight as well. Spread bores the way to go for street rodding. The 440 Chrysler NY'r Thermo was perfect for SBC 327 builds. Some versions had a cool solenoid activated idle circuit leaning feature that added to the idle loping of the cam which was always cool to kick in at a red light making it sound even badder...fun days for sure.

I saw a 1965 Chevy Impala 396/325HP with a factory installed Quadrajet carb. So GM introduced them in 1965. I had a 1985 Dodge pickup with a 360 and a factory installed Quadrajet. It ran great.

Love the Q-Jet! Lost count of how many of them I have fixed/overhauled/tuned. Doug Roe's book was the bible for these carbs.

You turned me back on to carbs and that’s all that matters 👍🏻

In 67 & 68 the intake manifolds had the exhaust heat crossover also going through under the base of the Qjet and used a thin gasket with the stainless steel thin heat shield. The old 2GC actually had the exhaust running through the base of the carb! In about '69 they deleted that system. Chevy did make a Qjet aluminum heat shield too

Qjet years were '65-'90 .. 1965 Chevelle 396 got them ... Ram Air 4 Pontiac , Buick GSX 455 and quite a few others were very high performance cars

They're my carburetor of choice for 4x4 use. If you're climbing a steep hill, they'll just creep along. Edelbrock/carter do ok too, but Rochester if far superior in that application.

I have an original Q-Jet on my 69 Corvette with a 350. Just put a kit in it. Works fine. 50 years old and no problems. What's not to like! 😎😎

I find it funny how the dog made its rounds around 4 X's while this video was made. This was another simple video on extra information that I just learned. Thank you and a hello from San Antonio, TEXAS.

Watched a super stock Camaro run 9's with a Q-jet, impressed me to no end.

Congratulations on your 4 years on the air helping out with their cars. I wish you a great Labor Day from my family to yours. I have been around from day one and I will be continuing to yak, like and share your videos until you go off the air. God bless you all and I will say the same for your friend The Bennett family. Good morning to you and I hope that you have the time to comment back. I had a few of them on late 70's Pontiac Trans Am's, Chevy Nova's, and a couple of Oldsmobiles I only had a problem with one that wouldn't idle and it sat at a car lot after being wrecked for a good time and a rebuild fixed it and it was the only problem with them I ever had. Great day to you all again, thanks for sharing your milestone with me and my family/friends.

My father built his shop, business, and reputation on that Q-Jet right there. He did them all, but that was his bread and butter. But the vast majority of all of them where for people just wanting to go down the road. Drivers not Racers. As for the Secondary Metering Well Plugs... that was dad's secret weapon for success in all that. We bought the factory Re-Build Kit for them, with the O-Rings (QJT-1 & QJT-2 part numbers if I remember right). Drill them out and pop in those plugs and they run forever. We used to buy them by the case, and still have about a half a case of them left over...... I think it was a $2 part and only took a couple minutes to install. One of these days (now that dad has fully retired) I'll get video of him installing them 1 last time. Good Video as always UTG!

You are absolutely correct Tony: Q-Jet fuel bowl is small. How do i compensate for that? Run Z-28 / Corvette / High Capacity fuel pump, remove internal fuel filter and run in-line filter. Change the tucked fuel line from pump to carb, (has too many bends) and run the line in a straighter fashion, away from the engine and insulate it. You are again correct when you say you can get away with it if your fuel delivery is top shape. Thank you, Keep up the good work. Pierre Lafontaine

Interesting theory about the fuel spec change. Less volatile fuel reduced passive emissions, part of it was emissions related.

My personal experience with carburetors has been mostly with the Quadrajet. Once I leaned how all the systems worked I found it to be the most tunable carburetor and I was always happy with the results. Easy starting, Smooth running engine throughout the RPM range and really good fuel economy. Yes it has it's issues but they all do. Electronic fuel injection has really put most carburetors out to pasture.

Got a Q-jet in my 63 nova wagon. I'm learning to swap out her old gaskets and I'm glad you mentioned the plugs, I'll look in there too. Thank you confidence building videos, it's you that have helped me through many understandings of my car :) Thank you...it means a great deal!!!!

I love the Q-jet. I always used air/fuel gages, vacuum gages, timing lights to tune them. I also found that a fuel pressure regulator helped with a lot of the fuel issues relating to heat and small bowl size.

If you look at 1967 Q-jets and their intake manifold, you will see they have a channel in the base plate that runs under the fuel bowl that is fed exhaust gasses from the intake. This heated and vaporized the fuel in the bowl. They did away with this passage in 1968 which solved a lot of the issues. If you don't drive in the cold, block off the heat crossover in the intake manifold and you won't have heat issues with the Q-jet.

JB Weld has always worked for me to eliminate the well plugs leaking. Although, using JB Weld that will hold up to modern ethanol enhanced fuels is imperative. Also, some of the later Q-Jets were sought after by street guys due to the larger fuel bowls. You’d know these in particular, as the air horn has more screws attaching it to the fuel bowl over their older derivatives. (Think just prior to the CCC carbs.) Those had double vacuum breaks, and the bigger float bowl. They were the Chevy hot rodders dream carb. I believe they were only made for a couple years before they all went CCC.

My ex-wife had a 79 TA, 403 olds. Engine, never started off a simple turn of the key, never could root out the problem, internal resources said that the fuel bowl would drain out.

I remember when the thermoquad rebuild kits came with the new plastic body, and when the quadrajet rebuild kits came with the foam plug, they worked well for me.

Actually a damn good carb - once you figure them out. I ran 'em on all my Chevys, a few Fords, even an IH pickup I had. Guys forget, at WOT any two carbs with the same airflow and fuel mixture make the same power. I like that the Q-jets fuel curve can be tuned so close, and the only issue with making big power is the tiny fuel bowl - which there's more than one way around. Holleys are fine - they're simple and easy, if that's all you want.

was reffered as Quadrajunk when i was in Highschool. most chevy when floored would just emit huge Black brown smoke cloud. and oh Thermo Flood

Uncle Tony thank you so much for taking your time to get online to explain carbs it's been very insightful

GM put a thin wide aluminum plate "heat shield" under the carb that dissipated the heat soaking from the manifold. It acted like a heat sink. A lot of people didn't like the way they looked and took them out. They really worked. Removing them would make the carb overheat. The air door tension spring adjustment is the #1 most effective cure for the secondary bog. The tension setting needed to be set correctly for every engine or the doors open too fast and it falls on its face at full throttle or too slow and it pops. Especially important on automatic cars for correct transition when the trans kickdown hits. Also vital for manuals that carburetor backfire at sudden stomp on the pedal. Like motorcycle carbs the secondary fuel metering needles also play a big role in proper tuning, but nobody ever messes with them and they weren't that easy to find back in the day. Everybody just bought rebuilt carbs, put them on, and expected them to work right out of the box.

My father could make a quadrajet carb produce he loved them too. He wasn't a professional mechanic but so many guys dropped carbs by the house for my dad to work on. Besides as you said they were the best moderate to higher performance carbs out there and they were cheap. After he passed in 06 I had boxes full of carbs and parts and I'll tell you I had guys begging for what I had.

Actually, it was a super thick fiber gasket. They began installing essentially a heat barrier to keep the carburetor cooler.

One of the best pieces of advice I ever got , was to be smarter than what you are working on or with .

I'm just happy you didn't shatter the glass on your patio table with the carbs

Had those on my first 76 Impala 400 small block. Got 20mpg if I stayed out the throttle and made the coolest sound wide open with the air cleaner top flipped over.

Thanks Tony for throwing me back in time. I will never forget the 70 Chevelle SS I had with the LS6 and cowl induction. I think the rochester was the 800cfm version. When the 4 barrels opened up the sound coming through the cowl induction was unreal. Thought it was going to suck the windshield out of the car. I had a buddy that did some modification to his on a 69 vette BB that supposedly got it to flow 1000cfm.

"My mother was a quadrajet", That is spectacular, definitely won't hear a better line on the internet today.. LOL

Three guys came to my garage one day about 10 or more years ago from the then known as Nashville Auto Diesel College. One of the guys was a regular visitor and familiar with most of what I was doing. Upon coming to the bench one of them looked at the to be assembled piece and asked, "Whats that?" I looked puzzeled and said to the group, "Your kidding me, right? Don't they teach you about that at NADC? (They were in school uniform as they were on lunch break.) It's a Quadra Jet carbureator.", I explained. There was a brief pause followed by the question, "What's a carburetor?" True story. This was a great video and thread like none I've ever seen!

I have found that a trans cooler between the pump and carb solves the heat soak issue. It can be 95+degrees and the carb is cold to the touch. Also insulating the fuel line from the cooler to the carb is a good idea.

Quite possibly the best carburetors ever made. An engineering marvel!!

My favorite carb!! I had rebuilt one for my car way back when, and the cold-started engine ran at exactly the same idle speed as the warm idle!

back in the 90's I swapped 2 or 3 different quadrajets to a 1984 chevy caprice station wagon. the first carburetor was not the correct carb for the year and the emissions control setup for the 305 V8. The other 2 carb swaps, one was from another caprice where a previous mechanic had slightly changed the idle mixture. I had a factory preset Q-Jet picked from the junkyard. My elderly friend who didn't want me to swap his carb was very skeptical about it. I said "if you don't like it, I'll put your carburetor back on it". After he saw his gas mileage improve, he didn't say anything about it. I had his stock carb that someone had already retuned and that gave me the opportunity to make other adjustments and I was getting good power from it. I had two rochester manuals that I had read cover to cover several times. Once I learned how to tune these quadrajets, I never even looked at any other type of 4 barrel carburetors. Now I'm playing around with a 454 RV and I have swapped my performance tuned carburetor onto it a couple of times (previously setup for a 350). a slight adjustment to the idle mixture and at wide open throttle, no bog no hesitation. On my previous motorhome with the 350, I did have issues with it bogging out at high throttle and I drove it with the doghouse off and the air cleaner removed so I could watch what it was doing. I actually had a worn out carburetor. So I swapped another carb on and kept making more adjustments. I wound up modifying the secondary fuel rods to make the fuel mixture a bit fatter for high throttle speed and that thing screamed.

They started using a thicker gasket under the carb and it solved the heat soak problems

My little brother and I thought our Buick 455 w/ quadrojet was fast until a 440 Thermoquad wasted us like we're setting the parking brake !

1966 was the first year GM used the Q-Jet. It was the standard carburetor on the 1966 Buick RIviera GS. The dual 4-bbl option was still twin Carters.

I've rebuilt a Qjet with the wrong rebuild kit because the parts store didn't have the correct one and it worked. I've broke down and sprayed one down in carb cleaner and starting fluid in a 1966 Olds 98 and limped it 30 miles home. Nothing wrong with it on a driver.

The moment I saw those wee primaries and honkin great secondaries I knew I never rebuilt one or owned one. But I rebuilt many earlier 4bbl GM carburettors and noticed that people would quite commonly lock the secondaries out to improve gas mileage. So based on that experience I think GM did a great thing to do an asymmetrical design.

How did that table not shatter 😂

I have an old neighbor that insists everything other than an Edelbrock is a Quadrajet. Every carb he sees. Holley 1850? "Junk quadrajets." Drives me insane. Love your channel.

Want to stop the vapor lock Tony? Put a fuel filter off a Dodge Diplomat with a 318 that has a return line nipple and put it as close to the carb as you can get it and run a return line to the tank. This keeps cool fuel to the carb and solvbes the problem. Years ago I converted several Chevy C10s with Olds Diesels and this was a problem with them because the factory fuel line ran close to the exhaust and would heat soak. These already had a return line no one used when converting to gas engine. Adding this solvedd the problem. As to the small bowl use a good Carter fuel pump like a Marine Pump. These made sure the Quadrajet could stay full of fuel in a boat that runs in a load all the time. As to tricks, bore the primaries for 2GC primary blades an dtaper the bore, instand throttle snap, bore the accell pump bore for a 2GC pump cup, redrill the secondary squirter outlets to discharge under the air valve not above it. Then when the secondaries open you get a fuel shot and can losen the air valve a little without a lean condition. You can also get long machine bits to drill the idle curcuits to make them richer or leaner. Most of these are 750CFM. there are some 650s and they are 750s with the secondaries limited in openning, 454 Chevys had 800s and 500CID Caddys had 850s, the primaries were a little bigger. It is a lot of work to make one trick but when you get there, they are bullet proof. Tune it and forget it. One more thing, the plastic floats will sink. Don't use brass, just keep a good float in it. They last a long time, just install a new one when you start.

I have a 1966 Olds which came with a Quadrajet so 1967 was definitely not the first year for the QJ. In fact, the 67 Olds came with a completely redesigned QJ compared to mine (vacuum damped secondary's rather than fuel dampened) so by 67 they were already onto a second iteration of it. Great video though, love the review.