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 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.
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
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.
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.
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.
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".
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.
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!
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.
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.
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.
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.
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.
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.
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 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.
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.
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.
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."
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.
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.
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.
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.
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.
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 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 😁
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.
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
Speaking of CAFE (Corporate Average Fuel Economy). As you know, it would mandate a fleet-wide average fuel economy standard. Simplistically, for every low-fuel-mileage Corvette sold GM would need to sell a bunch of high-fuel-mileage Chevettes to bring up the overall average. When the law was first proposed the UAW immediately protested, arguing that the Big-Three would simply import Japanese cars, slap their own label on it, then sell it stateside to up their fuel-mileage average. That would cost American jobs. Congress agreed and added to the law that CAFE would only apply to American-made cars. This made the UAW happy. But the Big Three responded, "What's an 'American-made' car?" They pointed out that they often buy sub-assemblies from outside the U.S., and that few cars were 100% made in America. After much negotiation, the number 75% was agreed to. That is, at least 75% of the car had to be made in the U.S. to qualify as an "American-made" car. And that became the law. Almost immediately, the Big Three looked at their biggest gas guzzlers and started producing 26% of them somewhere else. I recall that GM examined the Chevy Caprice and sourced non-essential items like the hood and interior from outside the U.S. Thus, in the eyes of the CAFE law, the Caprice was no longer an "American" car and thus its (poor) mileage wouldn't factor into the CAFE average. In later years, things like Marketing and Advertising costs were also baked into this 75%. Chrysler (and later others) then outsourced the advertising budgets to foreign agencies to reduce the domestic content. Several Congressmen and UAW workers lamented, "we didn't see that coming." PS - at least, that's the way I remember it. Others may chime in with more accurate details.
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.
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
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 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.
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 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.
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.
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.
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
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 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? 🫤
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 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 !
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.
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 !
Mr. B. Here ! 🍩☕️👀😎👍 : I have a Oldsmobile 1976 260cid with the early one , you may thinks it’s funny but mileage was great and the weight of the 3500 to 3600 mileage I got 25 mpg on long trips ! 🍩☕️👀😎👍
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.
I was in my teens and twenties during this time. I loved cars, and I worried about the direction it was going. I remember these pre-fuel injection contraptions. Emissions, emissions. Luckily I was poor and could only afford older cars anyway.
I have a 1978 Olds Delta with the Olds 350cid. I love the car. Once i removed the gigantic catalytic converter, ran dual exhaust. The car had excellent pickup power and it gives me 18mpg. Despite having the 2.41 rear it lights up the back tires pretty easily. While giving good hwy mpg. ( one will peel ) lol
My friend bought a 75 Buick Apollo and I remember we thought it was awesome that it came with what we **thought** was a 307 with a quadrajet. Seemed sluggish and we just assumed it needed some tuning up after sitting for a long time and had those malaise era highway gears in the rear end. When we started getting into it we were so confused when we found the dual jet. Never heard of it before! And of course that 307 turned out to be an Olds 260 as well with it's itty bitty pistons... Those were quickly removed in favour of a 400 Pontiac that was sitting around!
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!!!!!!
I'd guess it was just a business/engineering compromise to use the quad casting rather than design a new one or implement it before the new design was ready.
My first car was the family hand me down. 64 Olds Super 88, Starfire V8 394, 345 HP, Rochester 4 barrel carb. My dad and myself in learning, took the carb off and replaced the rear secondary fuel jets with the larger opening with the smaller opening front jets from a carburetor kit. Then all 4 jets had the smaller opening. It cut down on the power acceleration when you stomped into passing gear and I assume not use as much gas. The car at best got 12 mpg with the factory jets in 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.
The Pontiac 265 is the same as the 301 with the 2 counterweight crankshaft. Pontiac started doing such nonsense back in 1975. On their 400 (and for some reason only the 400) they made the webbing where the main bearing caps bolt into very thin. The main cap bolts actually penetrate the webbing. Neither the Pontiac 350 or 455 had this weakness. These are known as the 557 casting 400 blocks which are basically useless for anything above a stock rebuild. They were weak enough that Pontiac brought back the 1971-74 casting block for use for all W72 (high performance 400) for 1978 due to warranty claims. All stock 1977 W72 engines used the 557 block and were rated at 200 HP. 1978-79 were rated at 220 HP. The only 400 available for 1979 was in the Trans Am and Formula were all W72 engines which required a 4 speed manual. Pontiac officially ceased production of their 400 at the end of 1978.
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”.
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...
Quadrajet carbs were great, very adjustable and not super sensitive to contamination. I used to rebuild them in the 80's for $50 plus the kit and it took me about a hour. later models have a enrichment solenoid that made adjustments to the idle circuit very hit or miss.
Back in the day somebody who wanted better performance, but wanted stealth, would source a Quadrajet & the factory intake to go along with it. Assuming of course that there was a factory 4bbl option for a given engine. I wonder how many smog techs caught that.
Great idea for a video.....those first Qjets from '65 & '66 that everyone hates so much (like the one on your Toronado). They got a pretty significant redesign for '67 due to several design flaws. I'm sure you know the story but it would make an excellent video!
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
I remember another 2 barrel carburetor. I think it was also based on the Quadra jet. I think it was called the Vara jet. It was one small barrel and one large barrel of the Quadrajet. It was used on a lot of the 4 cylinders and some v6’s
The intake manifolds for the Dual-Jet were also 4-barrel manifolds but the secondary passages were not bored out, so they just must have found it cheaper to change the castings for a few years before retooling...
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 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 😂
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
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.
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.
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
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.
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.
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 😂
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.
Your technical knowledge and the content you produce is outstanding Adam, Bravo!!!!~~
Could not agree more!
i like quadjet carburetors.
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.
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.
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!
Hey look. The Chicago Cutlass’s engine pics starting at about 8 minutes in.
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 😊
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.
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.
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.
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.
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
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.
Are you going to give credit do John Kreuz for using his pictures??
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.
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 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 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 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.
I see Chicago Cutlass pics in here 😁
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.
Great topics of discussion here. You are producing some quality content 👍🏻
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.
I love quadrajets
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.
Good old Rochester Carburetors on Lexington Ave in Rochester, NY until 1995
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."
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.
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
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.
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.
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.
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 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 😁
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.
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
GM had warehouses full of spare intakes and filter housings they needed to get rid of.
Speaking of CAFE (Corporate Average Fuel Economy). As you know, it would mandate a fleet-wide average fuel economy standard. Simplistically, for every low-fuel-mileage Corvette sold GM would need to sell a bunch of high-fuel-mileage Chevettes to bring up the overall average.
When the law was first proposed the UAW immediately protested, arguing that the Big-Three would simply import Japanese cars, slap their own label on it, then sell it stateside to up their fuel-mileage average. That would cost American jobs.
Congress agreed and added to the law that CAFE would only apply to American-made cars. This made the UAW happy. But the Big Three responded, "What's an 'American-made' car?" They pointed out that they often buy sub-assemblies from outside the U.S., and that few cars were 100% made in America.
After much negotiation, the number 75% was agreed to. That is, at least 75% of the car had to be made in the U.S. to qualify as an "American-made" car. And that became the law.
Almost immediately, the Big Three looked at their biggest gas guzzlers and started producing 26% of them somewhere else. I recall that GM examined the Chevy Caprice and sourced non-essential items like the hood and interior from outside the U.S. Thus, in the eyes of the CAFE law, the Caprice was no longer an "American" car and thus its (poor) mileage wouldn't factor into the CAFE average. In later years, things like Marketing and Advertising costs were also baked into this 75%. Chrysler (and later others) then outsourced the advertising budgets to foreign agencies to reduce the domestic content.
Several Congressmen and UAW workers lamented, "we didn't see that coming."
PS - at least, that's the way I remember it. Others may chime in with more accurate details.
Yet one more stellar move by GM's bean counters.
Adam, At GM, was this carburetor known internally as the 'Where's The Beef?'
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.
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
Another lesson learned tonight... thanks for the great vids!
Interesting video! I didn’t know about this carb.
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 remember those carbs, used to see them on the Olds 260 and Pontiac 301.
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.
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 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.
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.
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.
Q-jet: The GOAT carb.
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
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 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? 🫤
Adam- another great video. I love them!
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.
Dualjet had metering rods instead of power valves. This let's you keep the fuel ratio closer to stoichiometric. Thereby better emissions.
So did the Quadrajet and the 2Jet. Metering rods was a Rochester thing.
@johnstrauss8061 Also the monojet but not the 2GC that this card replaced.
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 !
Just when I thought I knew a lot about American cars, you lob an oddball tidbit like this out!
Great, fun info, keep the hits coming!
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.
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 !
Mr. B. Here ! 🍩☕️👀😎👍 : I have a Oldsmobile 1976 260cid with the early one , you may thinks it’s funny but mileage was great and the weight of the 3500 to 3600 mileage I got 25 mpg on long trips ! 🍩☕️👀😎👍
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.
I was in my teens and twenties during this time. I loved cars, and I worried about the direction it was going. I remember these pre-fuel injection contraptions. Emissions, emissions. Luckily I was poor and could only afford older cars anyway.
I have a 1978 Olds Delta with the Olds 350cid. I love the car. Once i removed the gigantic catalytic converter, ran dual exhaust. The car had excellent pickup power and it gives me 18mpg. Despite having the 2.41 rear it lights up the back tires pretty easily. While giving good hwy mpg. ( one will peel ) lol
Had never heard of the dual jet!!
The Rochester plant still exists!
My friend bought a 75 Buick Apollo and I remember we thought it was awesome that it came with what we **thought** was a 307 with a quadrajet. Seemed sluggish and we just assumed it needed some tuning up after sitting for a long time and had those malaise era highway gears in the rear end. When we started getting into it we were so confused when we found the dual jet. Never heard of it before! And of course that 307 turned out to be an Olds 260 as well with it's itty bitty pistons... Those were quickly removed in favour of a 400 Pontiac that was sitting around!
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!!!!!!
I bet GM did that to save money on new air cleaner housings and filters.
I'd guess it was just a business/engineering compromise to use the quad casting rather than design a new one or implement it before the new design was ready.
My first car was the family hand me down. 64 Olds Super 88, Starfire V8 394, 345 HP, Rochester 4 barrel carb. My dad and myself in learning, took the carb off and replaced the rear secondary fuel jets with the larger opening with the smaller opening front jets from a carburetor kit. Then all 4 jets had the smaller opening. It cut down on the power acceleration when you stomped into passing gear and I assume not use as much gas. The car at best got 12 mpg with the factory jets in 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 had a 301 grand prix and a 307 olds both with the dual jet, really liked both as daily drivers with good gas milage.
The Pontiac 265 is the same as the 301 with the 2 counterweight crankshaft. Pontiac started doing such nonsense back in 1975. On their 400 (and for some reason only the 400) they made the webbing where the main bearing caps bolt into very thin. The main cap bolts actually penetrate the webbing. Neither the Pontiac 350 or 455 had this weakness. These are known as the 557 casting 400 blocks which are basically useless for anything above a stock rebuild. They were weak enough that Pontiac brought back the 1971-74 casting block for use for all W72 (high performance 400) for 1978 due to warranty claims. All stock 1977 W72 engines used the 557 block and were rated at 200 HP. 1978-79 were rated at 220 HP. The only 400 available for 1979 was in the Trans Am and Formula were all W72 engines which required a 4 speed manual. Pontiac officially ceased production of their 400 at the end of 1978.
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.
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...
Quadrajet carbs were great, very adjustable and not super sensitive to contamination. I used to rebuild them in the 80's for $50 plus the kit and it took me about a hour. later models have a enrichment solenoid that made adjustments to the idle circuit very hit or miss.
I thought I remembered them. Having a 2 barrel with one primary and 1 secondary.
You might be thinking of the Varajet - it was on a lot of the 2.8 GM v6es in the early 80s, like in the Celebrity and the S10 pickup.
@mtut I think you're right because my mother had a celebrity. And that's where I saw it.
Back in the day somebody who wanted better performance, but wanted stealth, would source a Quadrajet & the factory intake to go along with it. Assuming of course that there was a factory 4bbl option for a given engine. I wonder how many smog techs caught that.
Great idea for a video.....those first Qjets from '65 & '66 that everyone hates so much (like the one on your Toronado). They got a pretty significant redesign for '67 due to several design flaws. I'm sure you know the story but it would make an excellent video!
Thank you Adam.
I have one of those carburetors they use to call them a dummy four barrel 😂.
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 another 2 barrel carburetor. I think it was also based on the Quadra jet. I think it was called the Vara jet. It was one small barrel and one large barrel of the Quadrajet. It was used on a lot of the 4 cylinders and some v6’s
My dad loved the 2 barrel Rochester. He often changed 4 barrels over to 2 barrels.
The intake manifolds for the Dual-Jet were also 4-barrel manifolds but the secondary passages were not bored out, so they just must have found it cheaper to change the castings for a few years before retooling...