I remember back when most people didn't understand vacuum secondaries and would be extremely underwhelmed by the performance of their car or even sell them very cheap thinking there was something wrong with the engine 😂 I would help a fella every once in awhile fix his vacuum leaks and get his spread bore secondaries working properly and the surprise and smiles were absolutely priceless and it's something you just don't forget
@mikek5298 correct. But the air doors are vacuum controlled. So if you have insufficient vacuum to them, they open too early. Then you get a huge flat spot in power. Until you get to an rpm where the engine can process the extra air and fuel. And in some lower power applications, that may be never. That is why many people referred to the quadrajet as the quadrabog.
@AndyR1982 Never heard it called that in 4 decades. We said Quadrajunk. But they was either good or bad. No middle road. That's been my experience. Either bad ass or fat ass. 😂
I worked at an Oldsmobile dealership in the 70’s. Worked on a lot of cars with 260 c.i. V 8’s with dual jet carbs. They were pretty trouble free. They got great fuel mileage. Not a lot of power but smooth as silk. I bought a used 1977 Cutlass with a 260, pulled a medium size pop up camper all the way to Florida. Got over 17 mpg pulling camper. It would go the speed limit with no problem as long as you give time to get up to speed. Didn’t like big hills. Once in Florida I averaged 21 mpg that week without the camper. Mostly in the city. I’m sure it was the small engine with that carburetor setup that made it possible.
My first car was a 1981 Regal with the 4.3 liter engine and it was the most comfortable car I've ever had and it was really reliable. I drove it for close to 5 years then sold it to a friend and he drove it for a few years and then he sold it. Love to know if that car is still around and running 😂
I've been a tech since the late 70s. This was a bombproof carb. They just worked. The only drawback was they were very difficult to rebuild properly and tuning was next to impossible. I also have lived in Rochester most of my life. The Rochester Products building was mammoth and offered some of the best paying stable job opportunities in New York. It was a huge part of our Hay day.... Imagine, You've just graduated and have to choose from Kodak, Rochester Products, Xerox, Gleason Works all within a short drive.
Rumor had it that the throttle body injection system was a way of using lots of the old processes and equipment as Rochester Products moved to building port injection systems. It also required less training to get people up to speed. RP is long gone like many of the greatest American auto makers and suppliers.
the stock and superstock drag racers have NO problem tuning them,,,really basic and simple,,,if your having problems I suggest your not all that good with carburetors
@tomstiel7576 😂 Trust me, I'm checked out on carbs. Guess you don't understand what I'm saying,,, a rebuild and possibly a rejet on a stock smogger was a big bill for our customers... The ones that had to get to work, not putter in garages on weekends for fun.
@@LaPabstLove how strangers make a comment and then others determine their education and experience level on a sentence or 2. I've never typed a comment thinking anybody gonna judge either. Spelling 4 xample. Some read this and just can't help but say u didn't spell xample right. I know. I can spell. I just got big fingers and Lil letters. 😂
In a Cadillac olds dealer I worked at , I had no trouble with Quadra jets as long as I left them in the fresh cleaner solution with oscillating parts basket for at least an hour and used the gm carb kit. They ran smooth and like new.
Love it. I used to do this with mom's '73 Vista Cruiser with the 455. One time I forgot to flip it back when I brought the car back. Mom told dad that there was a problem with the car, and I caught hell....
That's how I remember a NA four barrel sounding, the quadrajet when you tip into it hard, then the downshift gear drop and rev rip. I've owned a few cars with that setup and they never disappoint
The 1977-1990 GM B-Body cars are the best cars for someone who can't afford a 60s car but doesn't want a modern vehicle. They're comfortable, stylish and durable. I miss my B-Body cars.
I'd take a downsize Ford over a downsize GM car. Where I am, the downsize GM cars are twice as expensive due to the big rim and subwoofer community. The Fords have a lower liftover, deeper trunk, more hiproom, more effective bumpers, and came exclusively with V8s. But, in my opinion, they are less full size, and more just good intermediates. If you compare them to a real full size car, you'll always be disappointed. But compared to the intermediates of the seventies, they're no larger, yet are more spacially efficient, roomier, more economical, etc. I would say it would be better to just spend the extra money and get a mid sixties automobile. Where I live, you can get a sixties Ford for less money than a downsize GM car. Chryslers are also less expensive than GM cars most of the time. I paid $800 for my 1968 Mercury Monterey, $500 for my 1972 Ford LTD, and $3,500 for my 1968 Pontiac. Of the three, the Ford and Mercury still run.
As I recall, the reason GM went with the DualJet over the 2GC was efficiency. The 2GC was an older design than the QuadraJet. As a result, the primaries on the QuadraJet were more efficient than the 2-bbl 2GC. It was easier to meet emissions and fuel mileage standards using half a QuadraJet than it would've been trying to modernize the 2GC.
@@kirkwennerstrom2506 it had bigger bores and venturi than the primaries of a q jet. I still have one on a buick v6 oddfire in a jeep. It's a great carburetor.
Never ran a DualJet, but did have a 2SE VariJet on a Pontiac 151 Iron Duke 4 banger in a 80 Jeep CJ5. The VariJet was a progressive 2bl with a small primary and large secondary much like the QuadraJet but with 2 instead of 4 barrels. The light CJ5 ran surprisingly well with it.
Plus the added low-end torque curve due to the smaller primaries. They were great in the day with an Edelbroc spread bore Performer and free flow exhaust.
I had a 77 Cutlass with a 350 a 4v carb and we had tons of GM cars and trucks growing up. My dad was a GM certified tech and was atop notch QJ specialist. I never saw ot at least noticed one of those of those 2v that were fully cast. But I never worked on a 301 or 260 either. My point is I learned something! I can't believe I didn't know. Thanks for the great cotent you create. I've been watching you for a few years now and I'm always happy when you drop new content. Very informative and interesting to me as I still love those older domestic cars. Keep it up, please. You are appreciated.
I had a customer who owned a 77 Olds 88 that had the full-size (early) Dual Jet carb. It was the first one I had seen. I certainly did a double take the first time I removed the air filter! I remember that car as having a 350 Olds V8, but it could have been the 260. My first reaction was: "How cheap can GM get?" Little did I know that it would get much worse.
Worked on a few of those back in the day. Reliable and worked well on those smaller V-8's. Actually a brilliant move when you think about it, in many cases these carburetors used the same air cleaner, throttle linkage, and sometimes intake manifold as the 4bbl.'s did.
I remember having one of those carbs. I was a Q jet guy for sure. My stepson was a little to excited about getting one of my camaros with a pretty hot 350 in it. I started to worry about him killing himself in it so I went to the junkyard and got one of these dual jets and put it on. He kept saying it doesn't run like when you drive it. I told him when he's smart enough to figure out why, then he would be ready for more power. It took awhile but he finally figured it out and in my mind it bought him some time to learn to drive. He actually did learn to hotrod like a mechanic instead of a leadfoot.
Yet equally as gutless. I had an ‘80 Cutlass with a 260 V8 and a 2.29:1 rear axle ratio and the horrible THM200 transmission. The 260 was completely gutless. It tossed the timing chain at 90K miles. I replaced it with an Olds 350 2bbl from a 1970 Delta 88 and a TH350 that I rebuilt in my garage. That car was a freeway cruiser. It didn’t shift out of first gear until 60 MPH at WOT. It also got half decent gas mileage if I kept my foot out of it, which rarely happened.
We avoided those Caddys like the plague at the auto auctions back in the day and they were everywhere. You couldn't swing a dead cat without hitting a couple at any given auction. Anything with the GM Quad 4 was also avoided. There was no shortage of specific cars to avoid. Remember Merkur? Too many to remember!
The 301 Pontiac with the DualJet was a good runner and got great mileage. I had a number of very happy customers with that setup in Olds 88's & Pontiac Bonny's. The 307 Olds was good also!
The 83-84 Hurst Olds with the lighting rod shifters had those Olds 307's with a supposedly better cam. They still didn't have much for power, but nothing did in those days. Damn cool car for that time period. My buddy bought one new and it made for a great cruiser.
I had a 301 in my '78 Grand Prix. Loved it until it lost all the nylon teeth on the timing gears, then consequently ran in a retarded timing state causing overheating.
@@davidphillips5395 I'm a big fan of the 307. Great engine for the G-body. My 85 Cutlass last over 400K without a rebuild. Would probably still be running if I hadn't wrecked it.
Trivia Tidbit - the shaker hood scoop on the Olds 403 in a Pontiac Trans Am you showed had the wrong sticker on it. "T/A 6.6" denoted the Pontiac 400 which was used on 4-speed cars. High-altitude cars and auto trans cars got the Olds 403 and the correct hood scoop lettering on those cars should say "6.6 Litre".
Man I had one of those old dual jets on my 75 omega for granted it had a 260 in it but that thing dead middle of winter as cold as it would get and that old junk you didn't even have to pump just bounce that key and she was idling smooth, that was the absolute best running engine I've ever had. Miss that old girl
The quadrajet also spawned another, the Varajet, that was a 2 barrel on Iron Dukes and a few others. It was the quadrajet split down the middle more or less to give a small primary amd large secondary
We got them in Australia from 1980-1985 on 1.9L i4s, and 173 + 202ci inline 6s in GM Holden models. Like the Q-jet, if you got it set right,it wasn’t too bad. But so many of them were hacked about with by people with only half a clue, and ran like a dog. The ones we got were called the Varajet II and were made in France, with GM Strasbourg cast into them.
Yes, and that made more sense to me than splitting the Q jet into the front half only. I seem to recall some S10 trucks had those. My guess is using only the front half resulted in a cheaper to manufacture carb.
I had one of these on a stock 1980 K5 Blazer with the 305, swapped later on with the intake and Qjet from a 305 Camaro and couldn't really tell any difference in power or MPG with the 305 being so anemic in stock form at the time. The Qjet sure sounded a lot better when you stomp on it and those secondaries opened up though, so there was that.
In '83 I bought a '79 Regal from a coworker. It had a 301 Pontiac V-8 with the early full-body Dual Jet carb and a 2.41 rear axle ratio. Highway mileage was unlike any V-8 I've owned before or since, besting my previous '67 LeSabre and '67 Skylark with 300 CI Buick V-8s and 2GC carbs. Drove the Skylark for 2 yrs, the LeSabre (not my last) for one, and the Regal for eight before each in turn was begged away from me for being so trouble-free. "Good old days."
I can't think of a more iconic duo than GM and creative attempts at cost cutting. I for one have always wanted to at least test drive one of the small little Olds 260s in a Cutlass, just to see how much of a difference there was between that, a 3.8 V6, and a 307. I'm guessing not much, since they didn't stick around very long.
I've had the experience of driving both a 3.8 (or 231) and a 260, and they perform similarly as you'd expect. However, the 3.8 got a tiny bit better mileage, but shook more.
My parents gave their 77 LeMans to my brother in 1983 and found the pcv hose completly blocked. We rebuilt the carb and couldn't believe it looked like a Quadrajet with the secondarys cast shut. After a tune up and some gasket replaced he drove the thing till 1987.
They later made one which was split the other way, with one primary and one secondary. I think it was called the varijet. It didn't really look like half a quadrajet but it was basically half of one.
Not really. The Varajet was a terrible carburetor. GM used it on a shitload of A and X cars, and we rebuilt a zillion of them in the ‘80s and early’90s. The grid heater under the carb was a common failure & it was fairly expensive at the time. Customers did not appreciate it when we’d call them and explain that the grid heater had failed & their carb rebuild price was going up by $75 or $100.
@@alantrimble2881 The version used on the Pontiac Iron Duke engines put into Jeeps in the early 80s didn't have a grid heater, just an electric choke element.
the carb at the 4:35 mark has been rebuilt and the hole drilled to adjust the cruise mix, I run these and they are Excellent carbs for daily drivers. I talked to one of the efi companies a few years ago when I was considering upgrading to efi. his answer was our efi systems wont add any fuel mileage over a well tuned Qjet, his honesty kept be from wasting money on efi to try to get better fuel mileage. the carb is basically set perfect and the exhaust has almost no fuel smell.
What I always thought funny is a 260 Olds and a 403 Olds are externally identical. !! The 403 Oldsmobile Small Block is a very underrated motor , I've built or owned 4 now , all ran well and no problems one was a stock bottom end 600 HP 6000 rpm motor still running today . That super massive bore of 4.351 inches is the biggest bore of any modern V8 ( bar a 460 Ford and that's only bigger by 0.009 ) , the little Olds has a bigger bore than a 500 caddy V8. It really wakes up with more compression/cam and that magic 3.385 (86 mm) stroke all Olds SB have is a great advantage. All modern motors use the 86 mm stroke, Ford, Toyota, Subaru, Ferrari, Lamborghini, ever wonder why 86 mm stroke comes up so often ? It's the perfect length for flame front progression and piston speed on modern fuels . ( When I say modern I mean post WW2 ) . Oldsmobile had that stroke by design on the first SBOs designed by Charles F Kettering.
@NillaRilla82 yeah they were always ahead of the rest of the field , the first modern V8 in 1949 ( caddy stole the design and they released almost the same engine in 1949) , the Gen 1 Olds were the top hot rod motor back in the 1950s into early 1960s . Your Grandad knows his stuff.
So I have to throw in some anecdotal experience, having grown up during the '70s. Quite a few friends and family had cars (mostly Chevys) equipped with 2gc carbs, model years '71 through about '75 and ALL of them had literally dangerous drivability problems until almost fully warmed up. Start the car, put it in reverse, it instantly dies. Restart, rev the engine, put it in reverse, it dies again. After at least a few cycles of this, the car would finally idle in gear, only to stall immediately once an attempt to drive away is made. This would continue for the next several minutes and eventually the cars would actually idle. Drivers quickly learned how to quickly re-start their cars while attempting to drive in city traffic. Rapidly pumping the gas pedal could sometimes prevent a stall, but it was kind of a tricky dance for the first several miles after a cold start, especially in the winter. OTOH, I also had several friends/ acquaintances with Q-jet cars (Cadillacs and Pontiacs mostly) that exhibited virtually none of this repetitive stalling behavior. BTW, this was in Illinois, so all off these cars had "49 state" emissions. My hypothesis on creating the Dualjet is that, for whatever reason, the primary side of the Q-jet was somehow able to meet the emission standards with minimal drivability problems vs the 2gc. The tiny cfm rating may well have helped the CAFE compliance as well. IMHO the 2gc cars were simply jetted too lean and /or the choke pull-off settings were simply too aggressive. BTW, busting "the caps" on the idle mixture screws did little to nothing to fix this problem; the main circuit was simply too lean until the engine was mostly warmed up. I would love to hear from anyone who was a mechanic during this period to see if they agree with this.
The hot air choke systems used up to the mid 70's had a lot of carbon plugging issues. Reduced heat to the choke caused many to be adjusted way to lean cold to get fully open hot. Later choke thermostat was pined to prevent adjustment and this would get modified to 'fix' a choke that wouldn't open fully. This resulted in the driveability issues you noted. Vacuum pulloff linkages could also be improperly bent in attempts to 'make it work ' without addressing the root cause.
Over the years, I had a lot of Quadajets. When they are right, I loved them. I only had 1 dualjet and it ran great. I had it on a 4.3 liter in a 1957 Jeep CJ5. I eventually swapped the whole thing out for a 350 with a quadrajet.
I had a 1980 Trans Am with the 301 V-8 and TH-350 transmission, and it was kind of a dog. After the engine overheated, I replaced it with a 1974 Pontiac 400 V-8 from a Catalina wagon. Installed a more aggressive cam, and used a 1968 4-bbl intake and Q-jet, true dual exhaust system, etc. The transmission I used was a 1970 TH-350 with a B&M shift kit. With those mods the car actually performed as you would expect from a Trans Am. It was like night and day. Your friend's '77 Firebird could be a real "sleeper" with a similar swap. Just a suggestion.
I’ve been turning wrenches for over 4 decades, and have never seen one of those, (the early version). Back when gas prices first went over a dollar per gallon, I remember a lot of people asking me to deactivate the secondaries on their 4bbls. Looks like GM took it a step further! My dad’s Pinto had a Weber on it that had a single primary and a single secondary. We used to refer to it as the “half-a-quad”.
I remember my moms friend bought a new 76 Grand Prix, had a 350 2bbl, (my parents had a 73 with 400 4bbl) I opened the hood on the 76 and wanted to see the carb, it was a quadrajet without the secondaries like this video is describing, I was kinda surprised. I was used to seeing the 2bbls on the early 70s 400s and 350s, which was the small round type carb, was a pretty 76 tho, white with blue interior, I rode in it once and was impressed with the quiet smooth ride, it was probably less than 6 months old at the time. Never forget little memories like that. in metro ATL! I was walking down the road and she stopped and asked me if I needed a ride, since she was headed to our house anyway, A/C was on and it was hot outside so I jumped in!
I've got an early "Dual-Jet" (in a Quadrajet body) Rochester out in the shed that my dad had saved. I never looked at it that close til a few,years ago. At first I thought I found a 4 bbl. Says DualJet right in the metal covering the secondaries. You can faintly see it on the left side in Adam's video. This made my day Adam, got me thinking about dad. Still got 1 or 2 301s in a big crate my dad built, he was a fan of them, he swapped a few of 'em into Bonnevilles and Grand Villes, and the 2.90 rear differential with it. I think that whole drivetrain, TH400 too, was in at least 3 cars my family had 😁
My first car (a hand-me-down from my parents) had a Chevy 305 V8 with a Quadrajet. By the time I started buying my own cars and working on them myself, I was buying mid-to-late '80s European cars with Bosch L-Jetronic and Motronic electronic fuel injection systems. So I understand electronic fuel injection systems far better than I understand carburetors. But I still found this video rather interesting! Thanks for the history!
I fitted one of these quadrajet carburettors on my 🇦🇺Aussie 253 cubic inch V8, along with a lot of other modifications including of course a different inlet manifold. (It came originally with a pretty awful Stromberg two barrel carby. ) That engine was sweet after my mods - plenty of power when needed, yet absolutely fabulous economy if driven sensibly.
I had a '79 camaro Berlinetta with Dualjet 305, turbo 350 trans and a 2.41 rear! Great highway cruiser, I guess the general didn't have enough overdrive trannys ready for the second oil embargo. Eventually, I put a Q-jet and intake and a 3.73 rear gear in it. That was TOO low. Love your vids.
I had a 1979 Caprice with the later Dualjet on a 305 engine. That brick of a car would average 18 mpg on the highway at 75 to 80 mph. Fantastic carburetor !
When I was in high school in the Mid90s in my auto tech class, we had a few of these duel jet carburetors we all agreed that they were the strangest thing we had ever seen lol
As an old guy mechanic , I had to work on all these carbs, and I am still a Q jet guy, yes a carb that is tough to tune, but if you really enjoy the big secondary and great wonderful primary with a double ventury that works. I get 17 mgp at 65 mph . Yes A Holley is easy to tune for the drag strip or oval, But I wont ever give up my Qjet I have a strong 406 sbc and it is on a stock Qjet , lots of power and is very reliable Its a big car (4600Lbs) , !977 Malibu 406, 3 inch exhaust with Flow mater 40s 700R4 with shift kit , 3:73 gear True Trac diff, newer axles , BFG tires , Damn Fun Bought
Bought a used 1977 Cutlass Supreme 4DR with 260 V-8 in 1985 when I first entered Real Estate from retired couple I used to deliver their newspaper, mow lawn, shovel snow and paint their home in College Park MD. The light blue metallic paint was already compromised, driver door hinge was worn/sagged, interior plastic/chrome trim was brown from tobacco smoke could never get the smell out of the interior! Ran smooth, decent gas mileage only replaced fan clutch in 2 years of ownership. Good highway vehicle.
All these years I thought I was crazy, but here it is. When I was a teenager I was helping my Dad change the air filter on his 1980 Chevy Caprice wagon with a 267 V8. I remember the carburetor looked like a Q-Jet but there were no secondaries - it was just aluminum casting over where the secondaries would be.
Years ago (1979) I knew a guy that had a 1970 chevy Impala with a 300 hp 350, he disconnected the mechanical linkage on his QuadraJet secondary's to get better fuel mileage. All he had to do was "keep his foot out of it". I would have never done that for those few times you wish you had not crippled your engine when you wanted all the horses.
I want one of these just to say I have one. I remember seeing what looked like a 2GC on a Chevy small block V8 in a 84 or 85 Suburban that was in the junk yard several years ago, and to this day I wish I had grabbed it when I had the chance.
That just blew my mind!! Holden equipped all 308 ci V8's with the Q jet between '69 and '88. The small 253 ci V8 was equipped with a Stomberg 2 barrel. The Australian motring public would not have accepted the dummy Q jet 2 bbl
I am a little surprised that you never mentioned doors cracking on the downsized Caprice. I owned, five of them, the first was a 85- and the last a1991, all station wagon's. I loved them. But everyone of them got a small crack in the door corner by the window, djust inside of the driver side door mirror. I think it was the sie view mirror weight that did it..I own a 1976 35000 mile Mercury colony park now.
Very interesting video! I am glad I never had the fortune or misfortune of working on one of those. I only worked on Autolite 2 bbls which rarely needed work.
I beefed up a lot of my cars in the 70's. I used mostly Carter carbs, often trading Holley's for them. I always considered Holley's to be garbage. I installed a few Rochester's and never had a single issue with them. They were reliable as hell. And I loved the sound of them when I floored the gas. I miss those days.
This carburetor was introduced in 1975, not 1977. My first car was a 75 Cutlass with a 260 and this was the carburetor it had on it. I was 17 at the time and originally thought I had a 4bbl when I took the air cleaner lid off, but I was very soon disappointed when I took a closer look. That poor car was slower than a glacier melting.
I believe it’s to allow the lines to flex with the vehicle body movement. Straight lines going up to a 90 degree into the master cylinder have a higher chance of breaking the seal or forming stress cracks during turns, acceleration, and just general body flex. The loops sorta make it act like a spring and the lines can compress and expand some
My 78 regal had a punched out 305, iron intake and a properly tuned qjet. With 2.41 gears it got mid to high 20s for hwy mpg, but the best thing was the gearing spread. 1st gear-60, 2nd-120, and i never got to the top of 3rd gear cuz i backed off around 145 due to front end lift. Loved slamming 1st gear at 50 on the on-ramps
I remember the Olds 260 V8 which had the 2bbl carb. Also the Chevy 267 V8 had it as well I believe. Not much experience with the Chevy 267 but the Olds 260 V8 was a weakling but at least a very smooth quiet engine.
Can’t even believe how many carbs I rebuilt over the years, probably close to 200. The q-jets were simple and pretty much reliable, the only one that was tricky was the Thermoquad, but a great design.
Our family's 1976 Buick Skylark had this early DualJet. The car had hard times starting in the winter, and had weak power on acceleration. I remember my dad and uncle always fiddling with the mixture and idle screws, and the choke to try and tune it to operate better.
I had an 82 Grand Prix with an electronic controlled/connected Dual Jet on a Buick 3.8L V6. I wish I had pictures of it but it had some more stuff going on where the larger secondaries are on a quadrajet. I had the service manual for the Grand Prix, that year also included a slightly larger v6 option, I think it was 4.1L that came with a quadrajet. This style carb meant the intake air cleaner assembly would be the same no matter which carb was used. They made electronically connected quadrajets also. My 81 Trans Am has a 400ci Pontiac V8bfrom a 78, for 2 years I ran a quadrajet, car ran fine but I swapped in an EFI system and it did modernized the car. What folks forget, carburetors would get flooded, didn't like to start in the cold, and every car had a different ritual with the gas pedal before starting. Some cars were an "art" to start. One thing a good carb like a quadrajet does is react instantly. Even the best cars today you can feel a slight delay in the gas pedal where a carb would react the instant you kicked down that pedal.
I once had a 1970 442 W-30, which had a rather unusual carb. It was the ordinary quadrajet except... it had no secondary metering rods. It developed the common bleed down problem, and I was advised to take it to a local carburetor specialist in Hoffman Estates IL. I removed the carb and took it to him, and upon his examination, he was shocked to see the lack of metering rods. The only thing in the bottom of the secondary were two rather large jets. He asked me "where the hell did I get this carb?" I purchased that car while on leave from the Air Force new. I told him it stock since I made no mods to the car (it was fast enough) He made the repairs and off I went. One week later I came out to my car and someone cut my hood chain and removed that carb. I could not find a replacement that would work on that stock manifold. I ended up putting an 850 Holley on a Edlebrock to get the car to even run properly. To this day I still don't know about that Quadrajet.
If you haven’t already, could you do a video about the rochester varajet carburetor. That was an interesting carburetor because rather than a Q jet cut in half horizontally, it was cut in half vertically. It was essentially a 1 barrel with a mechanical secondary. Didn’t produce a lot of power but was very reliable and worked well
I was a Pontiac guy back in the day, the 301 was offered with a turbo. I never had one but I herd they ran pretty strong until they came apart. The QuadraJet was panned by a lot of people, I think because they were complicated and harder to work on than some of the other carbs. Other problems were the small changes over its life leading people to use the wrong parts or even the wrong carb, the very small fuel bowl volume meant you had to have a good fuel supply, and the greenish anodized “Quadrajet by Carter” models had very soft castings. There were a lot of those and back in the day I had several helicoil kits to repair them. Just backing out a screw would sometime pull the threads out with it! When I heard the term QuadraJunk, I always thought of that and didn’t get defensive even though it was a pretty good carb…if it had a good casting,,,fuel supply,,,the right parts in it,, and in the right application. Oh, and the leaky machine plugs between the baseplate and the body, and the emulsion tubes that would often fall out of the top plate, and bent up accelerator pump linkage from people pulling the top without driving out the pump arm pivot pin, Oh, and the aggregating choke linkage down inside the body you had to fiddle with to get back in place. But other than that they were great…did I mention how much I liked Holly carbs? 🫤
When I installed a 231 CI Buick V6 in my 1980 Triumph TR7 Spider in '83 in CA, the engine came with the 2GC two barrel carb which performed quite well. But the intake manifold weighed a ton! Well, probably over 60 lbs at least. So I installed the intake manifold from the Cadillac 252 V6 that used a 4bb Q'Jet. The Caddy manifold, being aluminum, weighed less than 20 lbs, but of course it needed a 4 BBL carb, and being in CA and having to pass the CARB emissions referee I needed a 2BBL version of the Q'jet. It took a while to find one and set it up but it worked very well. Now I have the Spider in Oregon and have a 4BBL Q'jet in the Spider. Despite being only 231 CI, the Buick V6 will pull the secondaries open and issue a suitable increase in induction roar. NIce!
Watermarking them as his own is really low. Hoping your post in the group brings more attention to this. The community has gotten better at cleaning up these sorts of channels. There's a NASCAR channel that's been getting a lot of heat for basically copying from Wikipedia, or using other sources without credit.
That casting is like when Ford built the 90 degree 5.0L Jaguar AJV8 and then made it into a 90 degree 3.0L V6 by just not including the casting cores for the front two cylinders.
I would have a Rchester over a Holly any day. I love the old round top two jet you could rebuild it just as easy as a Briggs & Straton! The quadrajet I have rebuilt well over a thousand, adjusting and tuning that was what I got to be good with wright down to adjusting the vacume shift solinoid on the trans. The three tings I found helpfull on the q jet were, adjusting your accelerator pump to idle for the tip in squirt the next is to jet the primarys this is trial and sucess, the one not many know of on the right side under the upper secondarys butterfly shaft there is a set screw you can loosen and set the spring tension for the upper vacume butterflys, the lower secondarys are mechanical, its a matter of opening those vacume secondarys at the right time. It takes the bog out of the Quadrabog.
An irony: The late William Tyler Jenkins (aka Bill Jenkins) was interviewed right before his passing and noted he thought the Qjet was the best designed carburetor. I do not recall the publication, but the article was revealing in his journey (and the up's & down's) of performance developments. Spoiler alert: Bill noted the reason he quit college (Cornell) was attributed to his father being murdered by a hitchhiker in 1950. He (Bill) said that event 'messed him up pretty good' and going to work at the Olds dealership (w/old man Eisher [sp?] as his tutor] started him on the road to recovery by learning what made an engine tick.
You forgot to mention the other GM 2 barrel oddity from the 80's, the VariJet. That carb was a Q-Jet sawed in half front to back with 1 primary and 1 secondary circuit.
Thank you so much for your insight. I had the privilege of driving two different Oldsmobile 260 v8s One was a 1975 and the other one was a 1976 The 1976 came from California so it had all the California admissions and because of those the engine was much more gutless than the 1975. I rebuilt the carburetor on the 1976 and really to be honest there wasn't much to it and not much that you could do to get any more horsepower out of it through the carburetor. Around the city it wasn't bad but if you need to accelerate for passing or to get on a busy expressway it was nail biting..... gutlass....... Thank you again!!!!!!
Thank you for this video, I can relate to several vehicles from that era. I had a 77 Pontiac Bonneville four-door, with the 301 V8 a nd the Rochester dual jet. You were right it looks just like the four-barrel Rochester but without the two extra barrels. There was no reason under the sun for having that carburetor! Four barrels if you drive them right get better economy and when you need the power they have more power,, right?! The 301 engine put out $135 horsepower in 1977 up to 145 a few years later. I know that a Pontiac Trans Am and or Firebird with the 301 engine, four barrel carburetor with a turbo only put out 170 horse. I believe those were all Factory installed? My old Bonneville driving around home would get at best 19 miles per gallon, but when I went on a winter trip, from Wisconsin to Fort Lauderdale Florida my mileage would go from 19 up to 28 miles per gallon. I discovered that for every 3 pounds of air I would get one mile per gallon. Now I don't do that in extreme driving around home year round, but on a winter trip if you don't want to have to add air to your tires for the return trip, you can enjoy some awesome fuel economy. at the same time years ago we had a 77 3/4 ton Chevy 4x4 with the 350 and the four barrel carburetor, it put out 200 real horses! The truck was geared so that 60 was pretty much red line. Driving at 50 miles an hour the truck would get 9 miles per gallon. And this is about when they started putting the locks on from the factory so that you could not adjust the carburetor. It was either adjust the carburetor or get rid of the truck, so we took the locks off and adjusted it and achieved 15 Mi per gallon at 45 miles an hour and then one mile less for every 5 MI per hour more. We sold the truck a couple years later having put on less than 10,000 miles in that time. The neighbor bought it for the price paid, $6,200! They used it as a farm truck, pulling everything including, full Chopper box loads of silage. I would love to have both of those Vehicles back! Back then, I asked a mechanic about putting a four-barrel carburetor on my 301 and he said, quote, it doesn't have the right cam for it?? Is there any truth to that?? Thank you in advance for any help!
Its wild how how many pre 75 's got 20 mpg + ! I had 2 buick lasabres with the 454 2 bbl and an olds with a 455 rocket that still returned 20 mpg ! Reducing the compression and adding catylitic converters was a disaster for these cars !
Q jet were great cabs. The dueljet, pretty cool. One carb could do a video on, how Hitachi made cabs for the Nissan A series engines, a dual carb that as it aged was a mechanical nightmare especially in cold climate areas.
Love turning the Q Jet,, Instaled a $50 Q Jet carb kit with longer exhaust rocker arms and distributer recurve kit on a 1976 trans am firebird back in the day,,Dropped th ET from 17 teens in 1/4 mile to the 15 teens,, not bad for $50 kit...
I have a Varajet on my Opel Manta - a single primary and a single secondary - that's what I'd call half a Quadrajet but I guess it literally depends on which way you slice it !
Had a 66 Olds Delta88 Holiday coup with the 425 ultra high compression v8. I put an original Olds 4bbl manifold with a Quadrajet carb. Even with 14 inch tires I got 18 mph at 70+ miles per hr with the air on! I could give a 1970 400 Firebird a serious run for the money. Rated at 365 hp factory with single exhaust, seriously a cool car.😊
5:30 I can tell you never spent much time around GM old two barrel carburetors. The float would not stop fuel and the carburetor would flood out. The last time I drove one in 1995 this happened. It was a 1963 Pontiac Catalina. The engine was from a 1970 Fire Bird.
I've never seen that version of the dual jet, only the later version, I didn't even know they existed! You should do a video on the Holley Economiser that was popular in the late 70's and all through the 80's it was an odd but direct replacement for the quadrajet.
Also,not only using my pics without any real mention,you used a friends video of the operation of the clamshell tailgate, but just dubbing over his video. Real hackery, man. Just saying.
Cry us a river. He could've used video of urr Wife's clam opening and closing. 😂 OK that's a joke. I agree he should've said thanks to Kreuzcontrol for pics and vids of old lady's clam shell opening. 😂😂
I loved the Q-jet- I loved the sound of the engine when the secondaries opened up!
@@trampslikeus3575 Booooo-Waaaaaah!
Flip that air cleaner lid over, and let the fun begin!
Vtec before it was cool
@@michaeltucker9993 eeyup
@@michaeltucker9993💯💯💯 😂😂😂
I remember back when most people didn't understand vacuum secondaries and would be extremely underwhelmed by the performance of their car or even sell them very cheap thinking there was something wrong with the engine 😂 I would help a fella every once in awhile fix his vacuum leaks and get his spread bore secondaries working properly and the surprise and smiles were absolutely priceless and it's something you just don't forget
Quadrajets and Thermoquads are mechanical secondaries.
@mikek5298 correct. But the air doors are vacuum controlled. So if you have insufficient vacuum to them, they open too early. Then you get a huge flat spot in power. Until you get to an rpm where the engine can process the extra air and fuel. And in some lower power applications, that may be never. That is why many people referred to the quadrajet as the quadrabog.
@@AndyR1982 The secondaries of a Q-jet definitely have more tunability than most folks think, especially given the simplicity of how they operate.
I used to make good side money building and tuning Quadrajets. Fuel injection killed that for me.
@AndyR1982 Never heard it called that in 4 decades. We said Quadrajunk. But they was either good or bad. No middle road. That's been my experience. Either bad ass or fat ass. 😂
I worked at an Oldsmobile dealership in the 70’s. Worked on a lot of cars with 260 c.i. V 8’s with dual jet carbs. They were pretty trouble free. They got great fuel mileage. Not a lot of power but smooth as silk. I bought a used 1977 Cutlass with a 260, pulled a medium size pop up camper all the way to Florida. Got over 17 mpg pulling camper. It would go the speed limit with no problem as long as you give time to get up to speed. Didn’t like big hills. Once in Florida I averaged 21 mpg that week without the camper. Mostly in the city. I’m sure it was the small engine with that carburetor setup that made it possible.
That's pretty incredible considering
I got 11mpg 17mpg highway with my 2004 hemi ram 2 door short bed.
IIRC the Cutlass with the 260 also had the option of a 5-spd manual with overdrive, which was a first for Olds.
I had a 1981 Olds Cutlass, 260 , and the half quad. It was a good car ,GREAT LOOKING. But it earned the nickname GUTLASS CUTLASS. LIL😢
My first car was a 1981 Regal with the 4.3 liter engine and it was the most comfortable car I've ever had and it was really reliable. I drove it for close to 5 years then sold it to a friend and he drove it for a few years and then he sold it. Love to know if that car is still around and running 😂
I've been a tech since the late 70s. This was a bombproof carb. They just worked. The only drawback was they were very difficult to rebuild properly and tuning was next to impossible. I also have lived in Rochester most of my life. The Rochester Products building was mammoth and offered some of the best paying stable job opportunities in New York. It was a huge part of our Hay day.... Imagine, You've just graduated and have to choose from Kodak, Rochester Products, Xerox, Gleason Works all within a short drive.
Rumor had it that the throttle body injection system was a way of using lots of the old processes and equipment as Rochester Products moved to building port injection systems. It also required less training to get people up to speed. RP is long gone like many of the greatest American auto makers and suppliers.
the stock and superstock drag racers have NO problem tuning them,,,really basic and simple,,,if your having problems I suggest your not all that good with carburetors
@tomstiel7576 😂 Trust me, I'm checked out on carbs. Guess you don't understand what I'm saying,,, a rebuild and possibly a rejet on a stock smogger was a big bill for our customers... The ones that had to get to work, not putter in garages on weekends for fun.
@@LaPabstLove how strangers make a comment and then others determine their education and experience level on a sentence or 2. I've never typed a comment thinking anybody gonna judge either. Spelling 4 xample. Some read this and just can't help but say u didn't spell xample right. I know. I can spell. I just got big fingers and Lil letters. 😂
In a Cadillac olds dealer I worked at , I had no trouble with Quadra jets as long as I left them in the fresh cleaner solution with oscillating parts basket for at least an hour and used the gm carb kit. They ran smooth and like new.
Nothing better than a Q-jet 4 barrel with the breather turned over and your right foot putting a dent in the floor board. ✌🏻from Ga.
Love it. I used to do this with mom's '73 Vista Cruiser with the 455. One time I forgot to flip it back when I brought the car back. Mom told dad that there was a problem with the car, and I caught hell....
@ we were so poor growing up we did it on a 2 barrel 😂
Flip that lid, get the FULL POWER!! New stuff sucks. Greetings from Detroit and Happy Thanksgiving.
What about Carter thermoquad?
BAA WHOOOAAHHH
That's how I remember a NA four barrel sounding, the quadrajet when you tip into it hard, then the downshift gear drop and rev rip. I've owned a few cars with that setup and they never disappoint
The 1977-1990 GM B-Body cars are the best cars for someone who can't afford a 60s car but doesn't want a modern vehicle. They're comfortable, stylish and durable. I miss my B-Body cars.
I'd take a downsize Ford over a downsize GM car. Where I am, the downsize GM cars are twice as expensive due to the big rim and subwoofer community. The Fords have a lower liftover, deeper trunk, more hiproom, more effective bumpers, and came exclusively with V8s. But, in my opinion, they are less full size, and more just good intermediates. If you compare them to a real full size car, you'll always be disappointed. But compared to the intermediates of the seventies, they're no larger, yet are more spacially efficient, roomier, more economical, etc. I would say it would be better to just spend the extra money and get a mid sixties automobile. Where I live, you can get a sixties Ford for less money than a downsize GM car. Chryslers are also less expensive than GM cars most of the time. I paid $800 for my 1968 Mercury Monterey, $500 for my 1972 Ford LTD, and $3,500 for my 1968 Pontiac. Of the three, the Ford and Mercury still run.
@@ofp8574 I've had several downsized chevys all great cars i currently drive a 88 LTD crown vic daily.
Love my b body wagon it’s a 88 olds custom cruiser has a great ride easy to repair and honestly has pretty good build quailty
@@The_R-n-I_Guy I had a 75 Monty Carlo with 350. Bought it well used. Man it was Bug Ugly but it just flat out worked.
i like quadjet carburetors.
As I recall, the reason GM went with the DualJet over the 2GC was efficiency. The 2GC was an older design than the QuadraJet. As a result, the primaries on the QuadraJet were more efficient than the 2-bbl 2GC. It was easier to meet emissions and fuel mileage standards using half a QuadraJet than it would've been trying to modernize the 2GC.
@@kirkwennerstrom2506 it had bigger bores and venturi than the primaries of a q jet. I still have one on a buick v6 oddfire in a jeep. It's a great carburetor.
Never ran a DualJet, but did have a 2SE VariJet on a Pontiac 151 Iron Duke 4 banger in a 80 Jeep CJ5. The VariJet was a progressive 2bl with a small primary and large secondary much like the QuadraJet but with 2 instead of 4 barrels. The light CJ5 ran surprisingly well with it.
I have a Cimarron with the 112ci and the 2ESE Still trying to get it to idle.
Spread bore carburetors are my favorite on a hot rod. The way they open up and sound is great.
Plus the added low-end torque curve due to the smaller primaries. They were great in the day with an Edelbroc spread bore Performer and free flow exhaust.
Sounds don’t mean power 😂
Adam, could you do a story about when Honda adapted a GM 5.7L engine to use their CVCC head to meet emissions ? I think it happened in 1973.
@@65bugnut wow that would be awesome to see. You kidding or was this an actual concept? Seems like bore size/spacing would likely make it impossible
@@chuckwhitson654 it happened. Mr. Honda shipped a car to Japan, had his engineers work on it and sent it back for emissions testing.
@@boardnski156 cool. I'll be looking for that
Incredible question.
Your technical knowledge and the content you produce is outstanding Adam, Bravo!!!!~~
Could not agree more!
I had a 77 Cutlass with a 350 a 4v carb and we had tons of GM cars and trucks growing up. My dad was a GM certified tech and was atop notch QJ specialist. I never saw ot at least noticed one of those of those 2v that were fully cast. But I never worked on a 301 or 260 either.
My point is I learned something! I can't believe I didn't know.
Thanks for the great cotent you create. I've been watching you for a few years now and I'm always happy when you drop new content. Very informative and interesting to me as I still love those older domestic cars. Keep it up, please. You are appreciated.
That 260ci is so cute ❤ like it wants to be areal engine when it grows up 😊
They must be very rare!
I had a customer who owned a 77 Olds 88 that had the full-size (early) Dual Jet carb. It was the first one I had seen. I certainly did a double take the first time I removed the air filter! I remember that car as having a 350 Olds V8, but it could have been the 260. My first reaction was: "How cheap can GM get?" Little did I know that it would get much worse.
Worked on a few of those back in the day. Reliable and worked well on those smaller V-8's. Actually a brilliant move when you think about it, in many cases these carburetors used the same air cleaner, throttle linkage, and sometimes intake manifold as the 4bbl.'s did.
I remember having one of those carbs. I was a Q jet guy for sure. My stepson was a little to excited about getting one of my camaros with a pretty hot 350 in it. I started to worry about him killing himself in it so I went to the junkyard and got one of these dual jets and put it on. He kept saying it doesn't run like when you drive it. I told him when he's smart enough to figure out why, then he would be ready for more power. It took awhile but he finally figured it out and in my mind it bought him some time to learn to drive. He actually did learn to hotrod like a mechanic instead of a leadfoot.
Those smaller V8s were probably still better than the HT4100.
The Hook and tow special
Yet equally as gutless. I had an ‘80 Cutlass with a 260 V8 and a 2.29:1 rear axle ratio and the horrible THM200 transmission. The 260 was completely gutless. It tossed the timing chain at 90K miles. I replaced it with an Olds 350 2bbl from a 1970 Delta 88 and a TH350 that I rebuilt in my garage. That car was a freeway cruiser. It didn’t shift out of first gear until 60 MPH at WOT. It also got half decent gas mileage if I kept my foot out of it, which rarely happened.
The little Crosley COBRA engines made of stamped steel in the late 1940s were probably better than the HT4100. 🤣😂🤣😂
Absolutely.
We avoided those Caddys like the plague at the auto auctions back in the day and they were everywhere. You couldn't swing a dead cat without hitting a couple at any given auction. Anything with the GM Quad 4 was also avoided. There was no shortage of specific cars to avoid. Remember Merkur? Too many to remember!
The 301 Pontiac with the DualJet was a good runner and got great mileage. I had a number of very happy customers with that setup in Olds 88's & Pontiac Bonny's. The 307 Olds was good also!
The 83-84 Hurst Olds with the lighting rod shifters had those Olds 307's with a supposedly better cam. They still didn't have much for power, but nothing did in those days. Damn cool car for that time period. My buddy bought one new and it made for a great cruiser.
I had a 301 in my '78 Grand Prix. Loved it until it lost all the nylon teeth on the timing gears, then consequently ran in a retarded timing state causing overheating.
@@davidphillips5395
I'm a big fan of the 307. Great engine for the G-body. My 85 Cutlass last over 400K without a rebuild. Would probably still be running if I hadn't wrecked it.
Trivia Tidbit - the shaker hood scoop on the Olds 403 in a Pontiac Trans Am you showed had the wrong sticker on it. "T/A 6.6" denoted the Pontiac 400 which was used on 4-speed cars. High-altitude cars and auto trans cars got the Olds 403 and the correct hood scoop lettering on those cars should say "6.6 Litre".
WWWEEEEEEOOOOOOHHHH nerd alert! LOL
Yes this is true, goood to know.
@@johnstrauss8061 I prefer the Pontiac 400 over the 403 Oldsmobile any day.
Man I had one of those old dual jets on my 75 omega for granted it had a 260 in it but that thing dead middle of winter as cold as it would get and that old junk you didn't even have to pump just bounce that key and she was idling smooth, that was the absolute best running engine I've ever had. Miss that old girl
I'm not a Chevy guy at all....but that opening view of the Beige Caprice really hits home as styling like a Cadillac.
Caprices were great cars
This was very interesting, Adam. I enjoyed it and learned a few new things. Thank you.
Great topics of discussion here. You are producing some quality content 👍🏻
Hey look. The Chicago Cutlass’s engine pics starting at about 8 minutes in.
The quadrajet also spawned another, the Varajet, that was a 2 barrel on Iron Dukes and a few others. It was the quadrajet split down the middle more or less to give a small primary amd large secondary
We got them in Australia from 1980-1985 on 1.9L i4s, and 173 + 202ci inline 6s in GM Holden models. Like the Q-jet, if you got it set right,it wasn’t too bad. But so many of them were hacked about with by people with only half a clue, and ran like a dog. The ones we got were called the Varajet II and were made in France, with GM Strasbourg cast into them.
Yes, and that made more sense to me than splitting the Q jet into the front half only. I seem to recall some S10 trucks had those. My guess is using only the front half resulted in a cheaper to manufacture carb.
I had one of these on a stock 1980 K5 Blazer with the 305, swapped later on with the intake and Qjet from a 305 Camaro and couldn't really tell any difference in power or MPG with the 305 being so anemic in stock form at the time. The Qjet sure sounded a lot better when you stomp on it and those secondaries opened up though, so there was that.
In '83 I bought a '79 Regal from a coworker. It had a 301 Pontiac V-8 with the early full-body Dual Jet carb and a 2.41 rear axle ratio. Highway mileage was unlike any V-8 I've owned before or since, besting my previous '67 LeSabre and '67 Skylark with 300 CI Buick V-8s and 2GC carbs. Drove the Skylark for 2 yrs, the LeSabre (not my last) for one, and the Regal for eight before each in turn was begged away from me for being so trouble-free. "Good old days."
I had a Dodge tradesman 100 with a slant six with a one barrel carburetor i loved it
I had many slant sixes with the Holley 1920 and Carter 1 barrel carb, they were great except I could never remedy difficult hot re-starts.
I can't think of a more iconic duo than GM and creative attempts at cost cutting. I for one have always wanted to at least test drive one of the small little Olds 260s in a Cutlass, just to see how much of a difference there was between that, a 3.8 V6, and a 307. I'm guessing not much, since they didn't stick around very long.
I had an 81 Malibu Classic with the 267 V8. My friend would always smoke me in his Iraqabu Malibu 3.8 v6 manual.
I've had the experience of driving both a 3.8 (or 231) and a 260, and they perform similarly as you'd expect. However, the 3.8 got a tiny bit better mileage, but shook more.
Those downsized full-sized GM products were some of the best they ever made. Wonderful size and design.
Couldn’t have said it better myself.
You're not wrong. They were darn gppd.
@ glad you agree - this ks an excellent subscription
GM had warehouses full of spare intakes and filter housings they needed to get rid of.
In the mid-eighties I bought a beautiful ‘79 Malibu Classic Station Wagon. It had the 267 V-8 and got around town just fine. I wish I still had it.
My parents gave their 77 LeMans to my brother in 1983 and found the pcv hose completly blocked. We rebuilt the carb and couldn't believe it looked like a Quadrajet with the secondarys cast shut. After a tune up and some gasket replaced he drove the thing till 1987.
I loved the punch and sound of the 4 barrel opening up. I am seeking an old car to have it again
They later made one which was split the other way, with one primary and one secondary. I think it was called the varijet. It didn't really look like half a quadrajet but it was basically half of one.
Not really. The Varajet was a terrible carburetor. GM used it on a shitload of A and X cars, and we rebuilt a zillion of them in the ‘80s and early’90s. The grid heater under the carb was a common failure & it was fairly expensive at the time. Customers did not appreciate it when we’d call them and explain that the grid heater had failed & their carb rebuild price was going up by $75 or $100.
@@alantrimble2881 The version used on the Pontiac Iron Duke engines put into Jeeps in the early 80s didn't have a grid heater, just an electric choke element.
@gruberstein: not exactly. The secondary on Varajet behaved like a variable venturi carb.
the carb at the 4:35 mark has been rebuilt and the hole drilled to adjust the cruise mix, I run these and they are Excellent carbs for daily drivers. I talked to one of the efi companies a few years ago when I was considering upgrading to efi. his answer was our efi systems wont add any fuel mileage over a well tuned Qjet, his honesty kept be from wasting money on efi to try to get better fuel mileage. the carb is basically set perfect and the exhaust has almost no fuel smell.
Another lesson learned tonight... thanks for the great vids!
What I always thought funny is a 260 Olds and a 403 Olds are externally identical. !! The 403 Oldsmobile Small Block is a very underrated motor , I've built or owned 4 now , all ran well and no problems one was a stock bottom end 600 HP 6000 rpm motor still running today . That super massive bore of 4.351 inches is the biggest bore of any modern V8 ( bar a 460 Ford and that's only bigger by 0.009 ) , the little Olds has a bigger bore than a 500 caddy V8. It really wakes up with more compression/cam and that magic 3.385 (86 mm) stroke all Olds SB have is a great advantage. All modern motors use the 86 mm stroke, Ford, Toyota, Subaru, Ferrari, Lamborghini, ever wonder why 86 mm stroke comes up so often ? It's the perfect length for flame front progression and piston speed on modern fuels . ( When I say modern I mean post WW2 ) . Oldsmobile had that stroke by design on the first SBOs designed by Charles F Kettering.
Grandpa was born in 41 and said in his hotrod days the Olds engines were the go to.
@NillaRilla82 yeah they were always ahead of the rest of the field , the first modern V8 in 1949 ( caddy stole the design and they released almost the same engine in 1949) , the Gen 1 Olds were the top hot rod motor back in the 1950s into early 1960s . Your Grandad knows his stuff.
So I have to throw in some anecdotal experience, having grown up during the '70s. Quite a few friends and family had cars (mostly Chevys) equipped with 2gc carbs, model years '71 through about '75 and ALL of them had literally dangerous drivability problems until almost fully warmed up. Start the car, put it in reverse, it instantly dies. Restart, rev the engine, put it in reverse, it dies again. After at least a few cycles of this, the car would finally idle in gear, only to stall immediately once an attempt to drive away is made. This would continue for the next several minutes and eventually the cars would actually idle. Drivers quickly learned how to quickly re-start their cars while attempting to drive in city traffic. Rapidly pumping the gas pedal could sometimes prevent a stall, but it was kind of a tricky dance for the first several miles after a cold start, especially in the winter.
OTOH, I also had several friends/ acquaintances with Q-jet cars (Cadillacs and Pontiacs mostly) that exhibited virtually none of this repetitive stalling behavior. BTW, this was in Illinois, so all off these cars had "49 state" emissions. My hypothesis on creating the Dualjet is that, for whatever reason, the primary side of the Q-jet was somehow able to meet the emission standards with minimal drivability problems vs the 2gc. The tiny cfm rating may well have helped the CAFE compliance as well. IMHO the 2gc cars were simply jetted too lean and /or the choke pull-off settings were simply too aggressive. BTW, busting "the caps" on the idle mixture screws did little to nothing to fix this problem; the main circuit was simply too lean until the engine was mostly warmed up.
I would love to hear from anyone who was a mechanic during this period to see if they agree with this.
Never owned a 2gc car built after 1972. The pre-72 2gcs run very well.
The hot air choke systems used up to the mid 70's had a lot of carbon plugging issues. Reduced heat to the choke caused many to be adjusted way to lean cold to get fully open hot. Later choke thermostat was pined to prevent adjustment and this would get modified to 'fix' a choke that wouldn't open fully. This resulted in the driveability issues you noted. Vacuum pulloff linkages could also be improperly bent in attempts to 'make it work ' without addressing the root cause.
After about 1972 mechanical chokes . came with a choke pull off mounted to it's assembly to help open choke valve.
@@puffkendrick6850
Manual choke almost unavailable in 72, auto choke was standard for everything but the most stripped down vehicle.
@jeffhill3681 non electric,heat stove built into intake manifold type
Over the years, I had a lot of Quadajets. When they are right, I loved them. I only had 1 dualjet and it ran great. I had it on a 4.3 liter in a 1957 Jeep CJ5. I eventually swapped the whole thing out for a 350 with a quadrajet.
Adam- another great video. I love them!
My buddy in Seattle just bought a beautiful '77 Firebird Formula with the 301/dual jet combo.
He better plan on using the 301 as a boat anchor, and that carburetor as a wheel chock.
No doubt. A Pontiac 400 or 455 will bolt right in place.
I had a 1980 Trans Am with the 301 V-8 and TH-350 transmission, and it was kind of a dog. After the engine overheated, I replaced it with a 1974 Pontiac 400 V-8 from a Catalina wagon. Installed a more aggressive cam, and used a 1968 4-bbl intake and Q-jet, true dual exhaust system, etc. The transmission I used was a 1970 TH-350 with a B&M shift kit.
With those mods the car actually performed as you would expect from a Trans Am. It was like night and day.
Your friend's '77 Firebird could be a real "sleeper" with a similar swap. Just a suggestion.
@@mikee2923 I did talk to someone that put a 6.2 LS in place of one and now has more power
I’ve been turning wrenches for over 4 decades, and have never seen one of those, (the early version).
Back when gas prices first went over a dollar per gallon, I remember a lot of people asking me to deactivate the secondaries on their 4bbls.
Looks like GM took it a step further!
My dad’s Pinto had a Weber on it that had a single primary and a single secondary. We used to refer to it as the “half-a-quad”.
I remember the first time I came across one. It fooled me, followed by a head scratching moment as I had no idea there was such a thing.
I remember my moms friend bought a new 76 Grand Prix, had a 350 2bbl, (my parents had a 73 with 400 4bbl) I opened the hood on the 76 and wanted to see the carb, it was a quadrajet without the secondaries like this video is describing, I was kinda surprised. I was used to seeing the 2bbls on the early 70s 400s and 350s, which was the small round type carb, was a pretty 76 tho, white with blue interior, I rode in it once and was impressed with the quiet smooth ride, it was probably less than 6 months old at the time. Never forget little memories like that. in metro ATL! I was walking down the road and she stopped and asked me if I needed a ride, since she was headed to our house anyway, A/C was on and it was hot outside so I jumped in!
I've got an early "Dual-Jet" (in a Quadrajet body) Rochester out in the shed that my dad had saved. I never looked at it that close til a few,years ago. At first I thought I found a 4 bbl. Says DualJet right in the metal covering the secondaries. You can faintly see it on the left side in Adam's video. This made my day Adam, got me thinking about dad. Still got 1 or 2 301s in a big crate my dad built, he was a fan of them, he swapped a few of 'em into Bonnevilles and Grand Villes, and the 2.90 rear differential with it. I think that whole drivetrain, TH400 too, was in at least 3 cars my family had 😁
My first car (a hand-me-down from my parents) had a Chevy 305 V8 with a Quadrajet. By the time I started buying my own cars and working on them myself, I was buying mid-to-late '80s European cars with Bosch L-Jetronic and Motronic electronic fuel injection systems. So I understand electronic fuel injection systems far better than I understand carburetors. But I still found this video rather interesting! Thanks for the history!
I see Chicago Cutlass pics in here 😁
I fitted one of these quadrajet carburettors on my 🇦🇺Aussie 253 cubic inch V8, along with a lot of other modifications including of course a different inlet manifold. (It came originally with a pretty awful Stromberg two barrel carby. )
That engine was sweet after my mods - plenty of power when needed, yet absolutely fabulous economy if driven sensibly.
Yet one more stellar move by GM's bean counters.
Good old Rochester Carburetors on Lexington Ave in Rochester, NY until 1995
I love quadrajets
I had a '79 camaro Berlinetta with Dualjet 305, turbo 350 trans and a 2.41 rear! Great highway cruiser, I guess the general didn't have enough overdrive trannys ready for the second oil embargo. Eventually, I put a Q-jet and intake and a 3.73 rear gear in it. That was TOO low. Love your vids.
I had a 1979 Caprice with the later Dualjet on a 305 engine. That brick of a car would average 18 mpg on the highway at 75 to 80 mph. Fantastic carburetor !
When I was in high school in the Mid90s in my auto tech class, we had a few of these duel jet carburetors we all agreed that they were the strangest thing we had ever seen lol
As an old guy mechanic , I had to work on all these carbs, and I am still a Q jet guy, yes a carb that is tough to tune, but if you really enjoy the big secondary and great wonderful primary with a double ventury that works. I get 17 mgp at 65 mph . Yes A Holley is easy to tune for the drag strip or oval, But I wont ever give up my Qjet
I have a strong 406 sbc and it is on a stock Qjet , lots of power and is very reliable
Its a big car (4600Lbs) , !977 Malibu 406, 3 inch exhaust with Flow mater 40s 700R4 with shift kit , 3:73 gear True Trac diff, newer axles , BFG tires , Damn Fun
Bought
Bought a used 1977 Cutlass Supreme 4DR with 260 V-8 in 1985 when I first entered Real Estate from retired couple I used to deliver their newspaper, mow lawn, shovel snow and paint their home in College Park MD. The light blue metallic paint was already compromised, driver door hinge was worn/sagged, interior plastic/chrome trim was brown from tobacco smoke could never get the smell out of the interior! Ran smooth, decent gas mileage only replaced fan clutch in 2 years of ownership. Good highway vehicle.
All these years I thought I was crazy, but here it is. When I was a teenager I was helping my Dad change the air filter on his 1980 Chevy Caprice wagon with a 267 V8. I remember the carburetor looked like a Q-Jet but there were no secondaries - it was just aluminum casting over where the secondaries would be.
Years ago (1979) I knew a guy that had a 1970 chevy Impala with a 300 hp 350, he disconnected the mechanical linkage on his QuadraJet secondary's to get better fuel mileage. All he had to do was "keep his foot out of it". I would have never done that for those few times you wish you had not crippled your engine when you wanted all the horses.
I want one of these just to say I have one. I remember seeing what looked like a 2GC on a Chevy small block V8 in a 84 or 85 Suburban that was in the junk yard several years ago, and to this day I wish I had grabbed it when I had the chance.
Same here, saw one too, didn’t grab it. I’m sure there are more around….
It could have had an adapter plate to go from a four barrel carb to a two barrel. I don't know why someone would do that, but the technology exists.
That just blew my mind!! Holden equipped all 308 ci V8's with the Q jet between '69 and '88. The small 253 ci V8 was equipped with a Stomberg 2 barrel. The Australian motring public would not have accepted the dummy Q jet 2 bbl
I am a little surprised that you never mentioned doors cracking on the downsized Caprice. I owned, five of them, the first was a 85- and the last a1991, all station wagon's. I loved them. But everyone of them got a small crack in the door corner by the window, djust inside of the driver side door mirror. I think it was the sie view mirror weight that did it..I own a 1976 35000 mile Mercury colony park now.
Same outcome with drivers door cracking (by mirror) mid 80's Monte Carlo.
I have one of those carburetors they use to call them a dummy four barrel 😂.
Very interesting video! I am glad I never had the fortune or misfortune of working on one of those. I only worked on Autolite 2 bbls which rarely needed work.
Are you going to give credit do John Kreuz for using his pictures??
I beefed up a lot of my cars in the 70's. I used mostly Carter carbs, often trading Holley's for them. I always considered Holley's to be garbage. I installed a few Rochester's and never had a single issue with them. They were reliable as hell. And I loved the sound of them when I floored the gas. I miss those days.
This carburetor was introduced in 1975, not 1977.
My first car was a 75 Cutlass with a 260 and this was the carburetor it had on it. I was 17 at the time and originally thought I had a 4bbl when I took the air cleaner lid off, but I was very soon disappointed when I took a closer look.
That poor car was slower than a glacier melting.
2:20 mark .. .can someone explain the multiple loops in hard steel brake lines before they go downstream...?
I believe it’s to allow the lines to flex with the vehicle body movement.
Straight lines going up to a 90 degree into the master cylinder have a higher chance of breaking the seal or forming stress cracks during turns, acceleration, and just general body flex. The loops sorta make it act like a spring and the lines can compress and expand some
@billbob4856 OK, that makes sense.
Thanks Bill.
…and the downward spiral avoids airlock when bleeding.
@@randyfitz8310Thanks, that makes sense.
I remember those carbs, used to see them on the Olds 260 and Pontiac 301.
My 78 regal had a punched out 305, iron intake and a properly tuned qjet. With 2.41 gears it got mid to high 20s for hwy mpg, but the best thing was the gearing spread. 1st gear-60, 2nd-120, and i never got to the top of 3rd gear cuz i backed off around 145 due to front end lift. Loved slamming 1st gear at 50 on the on-ramps
Great video. Thank you for sharing! 💪👍💪
I remember the Olds 260 V8 which had the 2bbl carb. Also the Chevy 267 V8 had it as well I believe.
Not much experience with the Chevy 267 but the Olds 260 V8 was a weakling but at least a very smooth quiet engine.
I had the 260 with this carb in '76 Omega. Also had the weak T50 5-Speed trans, Issues aside, with that overdrive I could hit 28 Mpg with the AC on.
Can’t even believe how many carbs I rebuilt over the years, probably close to 200. The q-jets were simple and pretty much reliable, the only one that was tricky was the Thermoquad, but a great design.
Our family's 1976 Buick Skylark had this early DualJet. The car had hard times starting in the winter, and had weak power on acceleration. I remember my dad and uncle always fiddling with the mixture and idle screws, and the choke to try and tune it to operate better.
I had an 82 Grand Prix with an electronic controlled/connected Dual Jet on a Buick 3.8L V6. I wish I had pictures of it but it had some more stuff going on where the larger secondaries are on a quadrajet. I had the service manual for the Grand Prix, that year also included a slightly larger v6 option, I think it was 4.1L that came with a quadrajet. This style carb meant the intake air cleaner assembly would be the same no matter which carb was used. They made electronically connected quadrajets also.
My 81 Trans Am has a 400ci Pontiac V8bfrom a 78, for 2 years I ran a quadrajet, car ran fine but I swapped in an EFI system and it did modernized the car.
What folks forget, carburetors would get flooded, didn't like to start in the cold, and every car had a different ritual with the gas pedal before starting. Some cars were an "art" to start.
One thing a good carb like a quadrajet does is react instantly. Even the best cars today you can feel a slight delay in the gas pedal where a carb would react the instant you kicked down that pedal.
I once had a 1970 442 W-30, which had a rather unusual carb. It was the ordinary quadrajet except... it had no secondary metering rods. It developed the common bleed down problem, and I was advised to take it to a local carburetor specialist in Hoffman Estates IL. I removed the carb and took it to him, and upon his examination, he was shocked to see the lack of metering rods. The only thing in the bottom of the secondary were two rather large jets. He asked me "where the hell did I get this carb?" I purchased that car while on leave from the Air Force new. I told him it stock since I made no mods to the car (it was fast enough)
He made the repairs and off I went. One week later I came out to my car and someone cut my hood chain and removed that carb. I could not find a replacement that would work on that stock manifold. I ended up putting an 850 Holley on a Edlebrock to get the car to even run properly.
To this day I still don't know about that Quadrajet.
If you haven’t already, could you do a video about the rochester varajet carburetor. That was an interesting carburetor because rather than a Q jet cut in half horizontally, it was cut in half vertically. It was essentially a 1 barrel with a mechanical secondary. Didn’t produce a lot of power but was very reliable and worked well
I was a Pontiac guy back in the day, the 301 was offered with a turbo. I never had one but I herd they ran pretty strong until they came apart.
The QuadraJet was panned by a lot of people, I think because they were complicated and harder to work on than some of the other carbs. Other problems were the small changes over its life leading people to use the wrong parts or even the wrong carb, the very small fuel bowl volume meant you had to have a good fuel supply, and the greenish anodized “Quadrajet by Carter” models had very soft castings. There were a lot of those and back in the day I had several helicoil kits to repair them. Just backing out a screw would sometime pull the threads out with it! When I heard the term QuadraJunk, I always thought of that and didn’t get defensive even though it was a pretty good carb…if it had a good casting,,,fuel supply,,,the right parts in it,, and in the right application.
Oh, and the leaky machine plugs between the baseplate and the body, and the emulsion tubes that would often fall out of the top plate, and bent up accelerator pump linkage from people pulling the top without driving out the pump arm pivot pin, Oh, and the aggregating choke linkage down inside the body you had to fiddle with to get back in place. But other than that they were great…did I mention how much I liked Holly carbs? 🫤
When I installed a 231 CI Buick V6 in my 1980 Triumph TR7 Spider in '83 in CA, the engine came with the 2GC two barrel carb which performed quite well. But the intake manifold weighed a ton! Well, probably over 60 lbs at least. So I installed the intake manifold from the Cadillac 252 V6 that used a 4bb Q'Jet. The Caddy manifold, being aluminum, weighed less than 20 lbs, but of course it needed a 4 BBL carb, and being in CA and having to pass the CARB emissions referee I needed a 2BBL version of the Q'jet. It took a while to find one and set it up but it worked very well. Now I have the Spider in Oregon and have a 4BBL Q'jet in the Spider. Despite being only 231 CI, the Buick V6 will pull the secondaries open and issue a suitable increase in induction roar. NIce!
Wouldve been kinda nice if you had asked before using my pics. Those pictures underhood of the early ones are ones i posted of the Chicago Cutlass
Watermarking them as his own is really low. Hoping your post in the group brings more attention to this. The community has gotten better at cleaning up these sorts of channels. There's a NASCAR channel that's been getting a lot of heat for basically copying from Wikipedia, or using other sources without credit.
Mom had a 76 Olds Omega with the Olds 260 V8 that had one of these early dual jet carbs.
That casting is like when Ford built the 90 degree 5.0L Jaguar AJV8 and then made it into a 90 degree 3.0L V6 by just not including the casting cores for the front two cylinders.
I would have a Rchester over a Holly any day. I love the old round top two jet you could rebuild it just as easy as a Briggs & Straton! The quadrajet I have rebuilt well over a thousand, adjusting and tuning that was what I got to be good with wright down to adjusting the vacume shift solinoid on the trans. The three tings I found helpfull on the q jet were, adjusting your accelerator pump to idle for the tip in squirt the next is to jet the primarys this is trial and sucess, the one not many know of on the right side under the upper secondarys butterfly shaft there is a set screw you can loosen and set the spring tension for the upper vacume butterflys, the lower secondarys are mechanical, its a matter of opening those vacume secondarys at the right time. It takes the bog out of the Quadrabog.
An irony: The late William Tyler Jenkins (aka Bill Jenkins) was interviewed right before his passing and noted he thought the Qjet was the best designed carburetor.
I do not recall the publication, but the article was revealing in his journey (and the up's & down's) of performance developments.
Spoiler alert: Bill noted the reason he quit college (Cornell) was attributed to his father being murdered by a hitchhiker in 1950. He (Bill) said that event 'messed him up pretty good' and going to work at the Olds dealership (w/old man Eisher [sp?] as his tutor] started him on the road to recovery by learning what made an engine tick.
You forgot to mention the other GM 2 barrel oddity from the 80's, the VariJet. That carb was a Q-Jet sawed in half front to back with 1 primary and 1 secondary circuit.
Mainly used on 4 and 6 cylinder engines.
Thank you so much for your insight. I had the privilege of driving two different Oldsmobile 260 v8s One was a 1975 and the other one was a 1976 The 1976 came from California so it had all the California admissions and because of those the engine was much more gutless than the 1975. I rebuilt the carburetor on the 1976 and really to be honest there wasn't much to it and not much that you could do to get any more horsepower out of it through the carburetor. Around the city it wasn't bad but if you need to accelerate for passing or to get on a busy expressway it was nail biting..... gutlass.......
Thank you again!!!!!!
Thank you for this video, I can relate to several vehicles from that era. I had a 77 Pontiac Bonneville four-door, with the 301 V8 a nd the Rochester dual jet. You were right it looks just like the four-barrel Rochester but without the two extra barrels. There was no reason under the sun for having that carburetor! Four barrels if you drive them right get better economy and when you need the power they have more power,, right?! The 301 engine put out $135 horsepower in 1977 up to 145 a few years later. I know that a Pontiac Trans Am and or Firebird with the 301 engine, four barrel carburetor with a turbo only put out 170 horse. I believe those were all Factory installed? My old Bonneville driving around home would get at best 19 miles per gallon, but when I went on a winter trip, from Wisconsin to Fort Lauderdale Florida my mileage would go from 19 up to 28 miles per gallon. I discovered that for every 3 pounds of air I would get one mile per gallon. Now I don't do that in extreme driving around home year round, but on a winter trip if you don't want to have to add air to your tires for the return trip, you can enjoy some awesome fuel economy. at the same time years ago we had a 77 3/4 ton Chevy 4x4 with the 350 and the four barrel carburetor, it put out 200 real horses! The truck was geared so that 60 was pretty much red line. Driving at 50 miles an hour the truck would get 9 miles per gallon. And this is about when they started putting the locks on from the factory so that you could not adjust the carburetor. It was either adjust the carburetor or get rid of the truck, so we took the locks off and adjusted it and achieved 15 Mi per gallon at 45 miles an hour and then one mile less for every 5 MI per hour more. We sold the truck a couple years later having put on less than 10,000 miles in that time. The neighbor bought it for the price paid, $6,200! They used it as a farm truck, pulling everything including, full Chopper box loads of silage. I would love to have both of those Vehicles back! Back then, I asked a mechanic about putting a four-barrel carburetor on my 301 and he said, quote, it doesn't have the right cam for it?? Is there any truth to that?? Thank you in advance for any help!
I have one on my garage wall with the intake. Thanks for the video
Its wild how how many pre 75 's got 20 mpg + ! I had 2 buick lasabres with the 454 2 bbl and an olds with a 455 rocket that still returned 20 mpg ! Reducing the compression and adding catylitic converters was a disaster for these cars !
Q jet were great cabs. The dueljet, pretty cool.
One carb could do a video on, how Hitachi made cabs for the Nissan A series engines, a dual carb that as it aged was a mechanical nightmare especially in cold climate areas.
Q-jet: The GOAT carb.
Love turning the Q Jet,, Instaled a $50 Q Jet carb kit with longer exhaust rocker arms and distributer recurve kit on a 1976 trans am firebird back in the day,,Dropped th ET from 17 teens in 1/4 mile to the 15 teens,, not bad for $50 kit...
I have a Varajet on my Opel Manta - a single primary and a single secondary - that's what I'd call half a Quadrajet but I guess it literally depends on which way you slice it !
Had a 66 Olds Delta88 Holiday coup with the 425 ultra high compression v8. I put an original Olds 4bbl manifold with a Quadrajet carb. Even with 14 inch tires I got 18 mph at 70+ miles per hr with the air on! I could give a 1970 400 Firebird a serious run for the money. Rated at 365 hp factory with single exhaust, seriously a cool car.😊
Interesting video! I didn’t know about this carb.
In smaller circles, we affectionately referred to that carb as, the "Rottenchester Quadrabogg" ;)
5:30 I can tell you never spent much time around GM old two barrel carburetors. The float would not stop fuel and the carburetor would flood out. The last time I drove one in 1995 this happened. It was a 1963 Pontiac Catalina. The engine was from a 1970 Fire Bird.
My dad loved the 2 barrel Rochester. He often changed 4 barrels over to 2 barrels.
I've never seen that version of the dual jet, only the later version, I didn't even know they existed! You should do a video on the Holley Economiser that was popular in the late 70's and all through the 80's it was an odd but direct replacement for the quadrajet.
Also,not only using my pics without any real mention,you used a friends video of the operation of the clamshell tailgate, but just dubbing over his video.
Real hackery, man. Just saying.
Cry us a river. He could've used video of urr Wife's clam opening and closing. 😂 OK that's a joke. I agree he should've said thanks to Kreuzcontrol for pics and vids of old lady's clam shell opening. 😂😂
To be fair, I'll go look for your videos. I will probably not finish watching this video and will wait to thumbs up or down.