@@MUUKOW3 ,the single float & bowl stuffer work great. AFB's will work if you use springs under the needle assy. Holley's not so much. Q- Jet usually need the throttle shaft bushings replaced and I usually JB weld the dreaded body well plugs. That black rubber piece they provide just gets fuel soaked over time. There aren't many of these carbs left in tact anymore. I'm glad there are still people who like the Q-Jet. 😁
Always liked these carbs. Ran them on a 350, 400, 396, 402, and a 454. All worked flawlessly. First carburetor I ever rebuilt at 18 in the mid 80's on a 402 truck. From that day forward I was hooked on them and have rebuilt several for others and even tuned a few by doing the some of the things Bill describes, just not as in depth. Most thought a Quadrajet wouldn't work so good on a slightly more than stock engine. They were pleasantly surprised. Great video and will definitely watch the next one!
💯 agreed Just got one from Vans in Indy for my 72 396 k20. They are far better than others on carbs and electrical.... Had one on my S10 2wd blazer 350/ 700r4 and it got around 21mpg pulling 2 sleds up north
Bought a 1967 GTO from a lot for $400 in 1972 @ 15yo. Learned how to fix it the hard way (no google) and rebuilt the "Q Jet" with the Jiffy Kit instructions and detailed schematic. As a Master Auto Tech since 1984 I can tell you the Quadra Jet Carb is my favorite. Best choke system for cold starts, highly adjustable Fuel/Air mixtures and good acceleration while not dumping fuel like a Holly.
I run a qjet on my jeep. Great off road carb, idles really well at crazy angles. I was on a trail in lake havasu, az and was at a steep off camber angle, engine just purring. A gentleman who I didn't know came up to me after everyone got through the obstacle and commented "Boy, isn't fuel injection great", I of course replied "I wouldn't know", I'm running a Quadrajet! He didn't know what a Quadrajet was. I had to explain I was running a carb, he did not believe me! I opened the hood, he didn't even know what he was looking at. He had just listened to someone in the past about how bad carburetors are!
There was time in the mid 80s that you could walk into Canadian Tire and order a rebuilt Rochester for a Pontiac Trans Am 455SD and get a beautiful 800cfm race carburetor for $129. Whoever the rebuilder was, was sending out real nice units with well plugs redone and the epoxy never came off, and up number rods and hangers right out of the box.
In another lifetime I had a 1969 SS 427 Impala. It would not go from a standing start. I studied the specs in my Motor book and realized the spring resisting the opening of the vacuum flap was looser for a Corvette. I loosened the tension and suddenly I could set the world on fire from a standing start. 😁
When the Q-Jet is understood and set up properly, they sing. Brass power valves don't go to hell from today's MTBE fuels. The bloke I work with is the carburetor whisperer and has shown some of the methods of dialing a Q-Jet in. Properly done, there will be zero flat spot as the secondaries open and make the passenger soil their Depends... Q-Jets are function over form. Heavy float will cause some issues! There are some sneaky ways of setting up a Q-Jet for a given application. They can be highly reliable with proper setup.
"set up properly" That's the issue, They were tuned for application, auto or std, big cam or not, big Ci or not. You need a spring and needle kit that most back yard tuners didn't have. You could take a Holley 780 vac sec off of a 327 and bolt it on a 427 and not change anything. Didn't need to be a carb guru to run them. Maybe a Power Valve change bc your cam but very easy and very little. 850 Mechanical, chop the choke horn off and it's an 890cfm. This is a great video on the Qjet, Thanks to Bill Little and YT for the tips and tricks.
Very informative video, thanks for sharing. First Q jet I worked on was on my buddy's GMC Vandura. Was flooding and spewing black smoke with intermittent stalling. Set the float 3 times.. No difference. 4 th time I took the float out I noticed it to be heavy. Purchased a new float. It was considerably lighter in weight. Installed new float.Set to spec. .. Mission accomplished. Smooth idle, no stalling and no rich, black smoke.The original float was a composite material that had it's coating compromised and soaked up gas like a sponge to the point it was internally saturated. Have worked on several through the years and came to have them become my favorite carb.
Another great episode of Gold's Garage! The Quadrajet dates to the mid-sixties, it is as if they knew the game was going to change a decade down the road and they created a flexible design to adjust fuel delivery profiles. The design was solid from the start and it needed less to keep it current, it made it to the end of the 1980's for GM. It is amazing how they juggled and smoothed the transitions to the stages. It is almost like a CV carb in a rather heavy disguise. It has been a long time since I used a Quadrajet, last time was in my 1986 C10 shortbox, good fun and yes I admit it, I was a throttle plate driller. It did idle, smoke the tires and would also pull a trailer, life was good. (-;
Great video and I loved the cut-away view. Thank you for making this video and educating so many that the Quadrajet can be a great carb when set up properly = for fuel economy and performance.
I love the Q-Jet. some of the hottest cars from the 70s had Q-jets. 455 Buick GSX phase III, which is considered to be the fastest mid-sized muscle car from the 60s and 70s, had a Q-Jet. the Pontiac GTO and Firebirds all had Q-jets. Olds 442 400s and 455 all had a Q-Jets. I have two books on Q-jets. one is from Doug Row and the other is Cliff Ruggles. both are invaluable when tuning Q-jet. Q-jets don't leak around the fuel bowls like a Holley once you get them setup, they just work. the only thing you need to do to a Q-jet is change the fuel filter. I change mine every other time i change the oil. power valves don't blowout. also, there is nothing like the sound of a Q-jet at wide open throttle.
i recently switch from tbi on my 88 3500 454 silverado to edelbrock intake and a q-jet, i rebuilt my first q-jet carb that had been on my shelf for years, on my maiden voyage i traveled 675 miles with no hiccups, i have many other q-jets left to rebuild will be viewing this vid many more times as a guide. thanks for posting this educational program
All of us old guys have had one back in the days.When those secondaries opened up you could definitely hear it 😂.Very good reliable carburetor.Buddy of mine still to this day will not give up on his Quadrajets.All theses old school mechanical tech really does the job.I still run these poor man Muncie transmissions and they hold together under this 550 hp sbc.Stuff was so simple back then.
In my twenties I bought a book on Rochester carburetors and became self taught enough that I did carburetor disassembly and cleaning and overhaul kit parts replacement. In the early 2000’s I did a cleaning and kit parts replacement on an E4MC for my ‘86 Oldsmobile. Come to find out at the time that the air horn casting holes were too small and tight, not allowing the secondary air valve to open. I reamed the two holes with the correct number size drill and assembled the carburetor. What a difference it made even with that Oldsmobile 307 cu in engine when accelerating that Cutlass.
Wow! This is a fantastic clinic on Quadrajet carbs. Well done. My '76 Vette (L-82 motor) had a Quadrajet carb and the car performed well. The engine only made 210 hp but I never had any issue with the carb not functioning well.
I just happen to have the Rochester book by Doug Roe & Bill Fisher sitting on my coffee table! Pretty sure they recommend drilling out the two secondary passageways, but that book is decades old of course. Back when I worked in a carb shop in Prince George BC, most days I would rebuild at least one Q Jet, many days it was 3 or 4 including the re & re and setup.
The main vertical part of the secondary main passageway was not enlarged just deepened. The lower part of the passage was enlarged to the same diameter as the upper. Then you would make a tool to drive the air bleed tubes up a small amount. All this was to eliminate a restriction where the air bleed tube was at where the secondary main passage made a bend and the tube restricted fuel flow. Using Roes book ( by the way he was on the Q-jet design team ) I had my bone stock 300 horse 327 running in the mid 13's back in 1975. I started tuning Q-jets as a side gig after that.
That was the best and most informative video I’ve ever seen on Quadrajet carbs. Learned a lot. Back in the day I ran one on a Nova and it ran great. Best thing was if you kept you foot out of it you got better gas mileage than a two barrel because the primaries were smaller. The accelerator pumps would wear out kinda fast, but it was an easy fix. Yep always liked them. Worked good.
My cousin rest his soul had a '66 Chevy II Super Sport nova with a 327. He had the art down of keeping the carb tip top. He never bad mouthed the q-jet. He actually called it a quadra-jump.
Personally,I LOVE the Q-Jet! Once you ounderstand HOW it works,and the little quirks,and how to overcome the LITTLE things,it's not only efficient and responsive,but EXCITING when it works!
I found in years of drag racing that I could improve my ET with a Q-jet over the 4250 Holley! Once U understand how 2 set it up, It is flawless! Unlike the Holley, which needed tuning thruout the day 4 racing! Keeping a Holley idling properly consistently from day 2 day was also a nuisance! I know all the tricks 4 tuning both 4 maximum performance! The Q-jet is a no fuss all day, every day carb! And it got me .5 - almost a full second on the track! Just by swapping carbs! Great video, guys! Thanx! 👌❤️
No matter what size engine they are bolted to , they will never give more air/fuel than what it needs. They run terrific. Took me a long time to learn this.
I had a 79 one ton P30 5.7 liter with the Q Jet . I needed more power and better part throttle cruise mileage . With an aftermarket intake , dual exhaust and some tweaks with air bleeds / metering rods I was able to tune to exactly what I wanted . With some advance curve changes and running premium fuel this truck was amazing . Great power on wide open throttle acceleration and a very lean cruise . It was difficult to obtain a selection of metering rods and various parts but fifteen years ago it was still possible . I did sell the truck and for its replacement I went to propane power on a P40 two ton . Operating costs were cut in half even though it was a two ton . But up front costs building a propane engine were high . I finally obtained what I wanted ! Good video ! Thanks !
Greetings: Great presentation. It is nice 2 know there R still some of us good Rochester guys around. U have my salute and respect. Keep up the good work. Bsafe.
Did a body off only 67 elcamino with a non orig 350 and a 4 speed. Got it with a Qjet, contiplated going the holley route since im comfy with them, but decided on keeping it. Cliffs High Performance happened to be close to me and hooked me up. He put in new shaft bushings, selected all the parts I needed and put it together for me. Threw it on the car and I love it! Feel and sound when those big secondaries open up, love it!
I had a 1970 Chevy truck I bought a 365 horse 327 Corvette engine at a Auction rebuilt it all the way back to stock my Holley carburetor was junk I put a 800cfm Quadra jet off a 1969 ram air 4 400 Pontiac engine man what a difference Carburer stayed that truck ran 13:58 115 mph 3000 stall 4.11 gears Positrac
My best friend in high school... 35 years ago... Had a 78 Z28... The yellow one. 350. And it had a nice exhaust on it and the car sounded great. But when he punched it and those secondaries opened it let out this roar that couldn't be matched. And you suddenly became one with the passenger seat. I don't care what anyone says... When dialed in correctly... The Quadrajet is a Beast!
Nothing beats a well tuned qjet on a stock or mild build. Qjet works great with AC cars with the fast idle solenoid in HP builds. Only problem with them is people don't know how to tune them.
I remember rebuilding the Q jets in the 80s. I have forgotten all that stuff so this video is great and reminds me of some of that stuff. I'm glad I still have one Qjet left, just have to find it somewhere to use on a BBC
Greetings: I know a few people across the country that know Rochesters well. Others claim they know yet cannot prove it. Historical experiences have proven my knowledge, skill and proficiency. Me, not being authority, however I recognize knowledge and skill. I add this man 2 my list of yhe rare, few and knowledgeable. Good job sir. My compliments. Bsafe. Thx 4 the share.
Thanks, this was very interesting. Reading a book on things to do to a carb doesn't match up with what Bill explained. I an anxious to see him work a Q-Jet into a race carb.
I'm 62 and learned how to properly rebuild QJs by a guy named Jesse at Carbco in Lemay Mo. Way back in the early 1980s. I even rebuilt my 62 Olds 88 square bore QJ.
I once built myself a gas miser, had a 120 mile round trip to work everyday. I used a 1984 190hp L-69 305 from a Z-28. Did a basically stock rebuild on it, .030 flatops, cleaned up 416 iron heads with Manley replacement valves. 1.84/1.50. Nice valvejob and .012 milled off. Used the old GM "Z-28" springs, Comp roller rockers, a Comp 260 HE flat tappet cam, Edelbrock Q-jet pattern performer intake, old 1970s 4165 Holley 650cfm vacuum secondary carb, HEI distributor and 1 5/8 primary, 3 in collector Hooker headers. Backed up with a basicly stock rebuilt 200R4 trans and a 3-42 gear & Eaton posi. It was in a 1985 Pontiac Gran Prix. That car got 30+mpg on the highway and 25+mpg in town. And it would do 300ft smokey burnouts on 275/60/15 street tires. Looked good, sounded good, and it got extremely good MPG. And as a bonus it ran pretty good too. It was a low 14 second 1/4 mile car. Real good work car if ya gotta go far. Later on it ended up with a 600+hp 385ci sbc, T400/5000 stall, & a 12-bolt swap with a 4-88 gear. It evolved over the years. But the first build on it was all about how many mpg I could get out of it. It ended up as a drag car that got trailered to the track. But I was always impressed with how well that Q-jet replacement Holley 650 vac sec 4165 carb worked. Real good street carb in my experience with one. I like the Q-jets too. Built plenty of those as well. Good carb for many applications.
I rebuilt my first Quadra-Jet on my Dad's 67 327 Chevy pick up when I was 15.....it was scary, but I didn't have any pieces left over and it ran great! He was shocked!😂
Excellent info, I epoxyed the fuel wells that would leak and learned how to adjust the secondary baseplate screw, i made a small screwdriver to use upside down. I had a holley 6210 that the transfer tube would leak and preffered the q-jet to the holley.
did the well plugs leak after while gas will eat the epoxy al the info i looked up said yes put a holley in its place it really woke the car up set the tv cable up alse
@@dewwed1551 I didnt have any issues with gas eating the epoxy, however that was in new orleans in 1985-1992, gas may be different now on epoxy repairs, the way i knew the wells were leaking, was after i shut off the engine, vapor would come out the carb, and it was hard to start after sitting. Which holley carb did you go with? back in the day, q-jet manifolds prevented us from using square bore carbs, without afdapters. good luck youngblood
hey mike i watched a vidieo 2/3 yrs ago and that was the problem they even put threads and plugs with ep and after while they said it would leak i like my q jet but have to say the holly woke the car up did put the tv cable adapter on i hope the leaking can be fixed thx
It's funny how this popped on my feed a day after I thought about Quadra-jets for some unknown reason. I had one on my 360 Chrysler. Pretty ingenious, using the primary venturi vacuum to open the humongous secondaries instead of a mechanical linkage and needing an accelerator pump. WAY more logical than the original four barrel carbs.
One really important info note always check top when off for straightness /flat I have rebuilt many and have found most to be warped from over tighting the long bolts to much.
When he says Holly is uncomplicated who is he kidding. I have never had one but many Quader jets and they are by far the easiest to work on. One thing to remember is the Carburetor the Quadre jet replaced was an absolute nightmare with linkage going everywhere all needing adjustment to work properly. I had an owner once who called me Mr. Carburetor because I did so many. The truth be known I did hundreds that didn't really need it when all was said and done but it satisfied the customer and paid me well. I can tell you I never had one I had to modify with those rods into the secondary jets or anything else. the biggest problem was the plugs in the bottom leaking gas into the manifold fixed with two part sealer so they couldn't leak.
I started working on Mercruiser inboard and blue-water inboards in 1978, and attended the Mercury Marine schools at Auburn, Mass and East Brunswick NJ. Always loved the Rochester carbs, both the Quadrajet and the two-barrels, because we never had to touch them unless the boat had sunk or caught fire. We'd flush the engines, change the oil, add antifreeze to the blocks, pull the drives, and park them in the sheds. Never drained the fuel systems, and they fired right up next sprin. I had two stern-drive units that ran 15 seasons in salt water with nothing but standard maintenance, never touching the carbs, until they both needed valve jobs. If I got a sinker, I'd pull the carb, strip and clean it, install a new brass float, and reinstall. I have a Mercruiser Quadrajet off a 260hp SBC 350 I-O that the owner replaced with a throttle body injection unit, and will run it on my 1975 Plymouth Duster 360 instead of the Thermoquad. Thanks for the info!
@@Sunspot-19 I mean the Rochester was a more economic carby to run and smoother transition through the throttle positioning, were the holley was better for raw horsepower, foot flat to the floor.
I totally agree with you about the quadrajet, it's an awesome carburator and I NEVER had any problems with mine in a big block Buick, or my brother's Stage 1 , his NEVER gave any trouble at all, and we drove the crap out of those cars for years!
Quadrajet is a good design. The problem with the Quadrajet carbs is finding tuning information and components. Their design is similar to the Carter carbs but with the exagerated stead bore design. Once you get one set up correctly they seem to keep their tune better than Holleys. Just my experience as a 30 year mechanic.
My Dad loves the Quad. He installed the same Quad on several 63 Split windows, and even kept the one installed on a 210 1955 before it left his garage. He always said, "Ignorance is no excuse."
i always liked a quadrajet carbureteur on the older cars flip the breather top upside down it would moan i read that the the rods that goes through the side of the carb that has the rubber seals would wear out sucking air would make you think you had a vacuum leak !!! good informational video you could put bigger jets for more power good job men !
Need to do a video on the thermal quad even more misunderstood then the Quadra jet and was actually a improved version of the Quadra jet kinda of a blend of the Carter AFB and Quadra jet in one carb.
I still use a Quadrajet on my 77’ K10. It works well in the cold, but sometimes the choke doesn’t sit where it should or sometimes it doesn’t release off the fast idle cam. I need to give it a good cleaning and add some powdered graphite to all the linkages and moving parts to get at 100% again. I make sure to run non-ethanol fuel to minimize the fuel evaporation out of the bowl and it usually starts pretty quickly as long as it hasn’t sat for over a week.
The first three cars I owned after I got my license were all Oldsmobile 442's, a 68, a 70 and then another 68 and of course they all had Q-Jets. The first 68 at idle, would pretty consistantly mis-fire on random cylinders, but would drive down the road pretty well, at least until you floored it! Then it would just fall on its face for a couple seconds before it would start taking off! Luckily for me my neighbor was a Q-Jet fan and helped me rebuild mine and showed me lots of tips on making them work correctly. That car ran so nice after the rebuild, no more misses from fuel dripping in the carb bores and no bog when you punched it after fixing the problems with the secodary air valve, now when hit it, it just went! After that I never even considered running any other carb on my Oldsmobiles. Another carb I liked because it always worked so well, but only had experience with one of them, was on a friends 70 Dodge Dart Swinger 340, it was a Carter AVS. Has anyone else had experience with them, and did they like them too? Thanks for the great video! I still have a few Q-Jets around, I just wish I had something to put them on!
I hung out with car racers on Sundays in the early seventies, in New Jersey, who ran a 68 Camaro 396 wedge motor automatic in Super Stock. They had a Q-Jet on it they said ran as good as a Holley. Q-Jets leaked after a few years, but so did Holleys. Just tightening up some screws solved the problem with both. You can change jets in both carbs. You could change the rods in the Q-Jet secondaries. You can change the Q-jet secondary flaps opening by bending a tab. The Q-Jet could be modified to do anything you wanted it to do. And they were cheap. And you could buy a mod kit from your local hot rod store with an assortment of jets and rods. I texted this before the video began.
You are one of the few that knows the qjet. I can only add the stock fuel filter can be restrictive. And use an external one and leave the carb one out. Also the hole in the carb body and or the fuel filter housing can be more restrictive than the needle seat. The fuel pump plunger spring and the accelerator pump jets also can be tuned. Keeping the float low can limit the amount the needle opens and can create more of a problem than sloshing. Maintaining fuel pressure is important on high hp cars as a these can pass a lot of fuel. Use on engines over a real 450 hp they need to be built right and i’m sure you build them right for the application. Well done.
I always pitched the stock filter and opened up the carb body hole too. I also found that leaving the float level alone and taking precautions to deal with sloshing worked better than lowering the level. Great additional info.
In Raleigh there was a black man that ran a shop near Ray Price Harley Davidsons dealership. He NEVER advertised but everyone knew if you wanted your Quadrajet to operate at PEAK he was the man. My 76 Malibu with stock intake and manifold ran rings around my friends 74 Malibu. He was using a brand new Holley 4 barrel intake, Holley Carburetor, and Headers. He could never keep up!
Q-Jets are awesome!!! Built many of them, 22 years in the auto repair business, the ones with the forward facing fuel inlet are Pontiac, Buick and Olds, I put them on everything
Holleys are getting expensive.I'm looking into putting the quadrajet back on my camaro.After watching your video I'm convinced.Thanks for the great information on these Q-jets.
ran a qjet on my '74 Buick455,ran great,really helped when I installed a stage1 fuel pump with a 1/4 return line back to the tank pulled 14.8 in the quater mile bone stock 8:5 compression,cheater slicks and variable pitch T400,2200 stall
Single biggest issue with tuning these is the parts availability. Edelbrock carried some for when they were manufacturing them, but to find a set of primary metering rods or primary jets in a typical town is virtually impossible.
Yes sir carburetors can be a tricky wheel. I myself prefer a Rochester carburetor for a stock application. Like most people I might prefer a Holley for performance applications, but for the reliability and simple operation I think a Rochester unit fills the bill. However, I have run into people who know more about the modifications that can be done to Rochester carburetors to have them perform better. Always learning things about carburetors, they are really engineered and most of us do not understand that engineering but this video helps unlock what is done here and also helps one to understand the workings of the carburetor.🥸👍👍👍👍👍👍
I used to race with a Quadrajet. So easy to tune at the track. Don't have to worry about gaskets leaking. No power valve to leak. The Carter AVS was a good carb, but not as big. Tried running a Holley, but never ran as good. I think I still have a few Quadrajets stashed someplace.
I used to go car-by-car in Pick Ur Part yards in the 80s to collect metering rods and hangers from Q-Jets. I had quite a collection back then. My 69 Firebird had a built 455. I was able to contact an old engineer at GM who actually provided me with the build specs for the Q-Jets from the performance 400s and 455s on the Pontiacs back in the 70s. Could practically duplicate them. It was easy to find the larger Q-Jets back then.
The Quadrajet is really a excellent carb! especially for mild to moderately built street performance engines. Sadly it is also a very misunderstood carburetor. that buwhaa sound when the secondaries open they make, through a low restriction air cleaner along with that nice high torque acceleration rate is super cool too! set them up right and you get easy starts, decent gas mileage and strong, great reliable performance.
@@goldsgarage8236 Not only did he do a great job, he took the time to have me in the shop and go over the problems with the trans and also explain how he was modifying it for racing abuse. I'll have to drop by and see Bill. He's a great guy and I lost contact with him when his Belmont location closed up.
Thia was some great information! I learned a few thing today on these carbs. I have been messing with my 800 cfm Qjet for my 502 big block and I cant wait to get out there and try some mods. THANK YOU FOR THE VID!
I've owned a few autos with Quadrajet carbs. I never was a fan of Holley carbs. The only problem I've had with the Quads is warping of the base. After the first time I learned how to recognize when it warped and would take it off and mill it back flat and it would work perfecting. That only happen on one vehicle which was a 1966 Impala SS 396.
I like the durability of the Quadrajet but the Holley dual accelerator pump 4 barrel with it's mechanical secondaries was always easy to tune so that was my race carburetor in the years before their metering blocks started warping all the time. Then, and to this day, I chose the Edelbrock AFB design carburetor.
To my knowledge, I’m a Ford guy, there were good or bad, the Pontiac that I drove had one, never had a problem. Much, much later, after learning more about carbs, I now wish to bolt one on my Jeep, that has a 4.7 Stroker.
Secondary opening rate is actually controlled by the vacuum pull off more than the spring tension adjustment is secondary to it. Early first Gen Quad had a slow 2.5 second opening rate and the rod connected to those flaps means regardless of how much engine pull or rpm is under it , it still takes ,2.5 seconds to allow it to fully open then in 70s they started changing the vacuum pull off to 1.0 seconds start to finish of letting the flap wide open and what ya really want. Eliminated bog of a broken one but opens quick enough to be just as quick on the track as any Holley and as discussed will support 9 second 1/4 n/a drag cars. I have gone 6 sec 1/8 with mine
I was always a Quadrajet fan. Never got along with the Holley and those power valves . I like the yhe Cafillac quad thas has the adjustable mid throttle screw.
I forgot the one thing with Quadrajets is that they were individually set for each engine they came on so just swapping them around didn't always work out so well . Look for the ones with the external metering adjust. Gives you that extra bit of tuning.
I ran nothing but "Q-Jets" back in the day. I had 2 that didn't work right and both were very simple mistakes that I MADE and were EASILY corrected. I thought Quadrajets were terrific, and as we all know, sounded fantastic when the secondaries opened. I don't recall anyone who didn't run around with their factory air filter lid flipped over to hear that sound.
As 16 year old kid, that's the first thing I did, well after I put a 4 BBL QJet on a 283 Impala that really didn't need it, my dad thought I was nuts!!.....maybe I am still lol
@@billlittle4285 I had a '79 Camaro with a 305 "Duojet." I swapped to an aluminum 4 barrel manifold and a Qjet. Sounded good, but at times smoked like a diesel. WAY too much fuel! People asked why I did it. Easy, the parts were free!
Everybody says they’re the worst carburetor made. I found out those people don’t know how to adjust the upper plate on the secondaries. One simple thing leads so many people down the road of throwing them out and giving up.
It was a great carburetor you had the follow all the adjustments once they were set it worked perfectly. They didn't like dirt they didn't like dirty fuel filters.
I still have the rebuild manual's for Qjet's etc..,i. rebuild several and replaced it with Holley 650 Spreadbore which i had no problem swapping jets and rebuilding back then.
The only people who say Q-Jets are junk are either too stupid to understand them, too stubborn to learn, or both.
Matt, I agree. they perform great if a person takes the time to learn them. They work off road almost as well as fuel injection. 😄
@@kensnyder2340 Yeah they don't flood on steep hills like an AFB or Holley.
@@MUUKOW3 ,the single float & bowl stuffer work great. AFB's will work if you use springs under the needle assy. Holley's not so much. Q- Jet usually need the throttle shaft bushings replaced and I usually JB weld the dreaded body well plugs. That black rubber piece they provide just gets fuel soaked over time. There aren't many of these carbs left in tact anymore. I'm glad there are still people who like the Q-Jet. 😁
They do not understand carburetion from the word go. Sorry about their luck. When things are in calibration, most carbs are good to go.
@Sunspot-19 There are a few out there that are turds like Ford's variable venturi that come to mind .
Always liked these carbs. Ran them on a 350, 400, 396, 402, and a 454. All worked flawlessly. First carburetor I ever rebuilt at 18 in the mid 80's on a 402 truck. From that day forward I was hooked on them and have rebuilt several for others and even tuned a few by doing the some of the things Bill describes, just not as in depth. Most thought a Quadrajet wouldn't work so good on a slightly more than stock engine. They were pleasantly surprised. Great video and will definitely watch the next one!
I reind the beginning of this video to get this guy name. His name is Bill Little of Belmont Automotive.
Greetings: U said it. Same here.
💯 agreed
Just got one from Vans in Indy for my 72 396 k20. They are far better than others on carbs and electrical....
Had one on my S10 2wd blazer 350/ 700r4 and it got around 21mpg pulling 2 sleds up north
@alfee9411 Greetings: 72 K20, I wanted 1 of those 4 my collection. Bummer I had 85 instead.
I have a q jet on my sbf 331 and it likes it.
Bought a 1967 GTO from a lot for $400 in 1972 @ 15yo. Learned how to fix it the hard way (no google) and rebuilt the "Q Jet" with the Jiffy Kit instructions and detailed schematic. As a Master Auto Tech since 1984 I can tell you the Quadra Jet Carb is my favorite. Best choke system for cold starts, highly adjustable Fuel/Air mixtures and good acceleration while not dumping fuel like a Holly.
It's even better when the Thermac hasn't been deleted!
I run a qjet on my jeep. Great off road carb, idles really well at crazy angles. I was on a trail in lake havasu, az and was at a steep off camber angle, engine just purring. A gentleman who I didn't know came up to me after everyone got through the obstacle and commented "Boy, isn't fuel injection great", I of course replied "I wouldn't know", I'm running a Quadrajet! He didn't know what a Quadrajet was. I had to explain I was running a carb, he did not believe me! I opened the hood, he didn't even know what he was looking at. He had just listened to someone in the past about how bad carburetors are!
Yep, Q-jet`s are great off-road carbs. Much better than a Holley.
Part of it is how the float doesn't happen to sink and flow fuel all over the place! Heavy floats are off road's Archille's.
Well the carb story just stuck around with the points stories...
fuel doesn't slosh around in a bowl its more like a fuel injection throttle body
There was time in the mid 80s that you could walk into Canadian Tire and order a rebuilt Rochester for a Pontiac Trans Am 455SD and get a beautiful 800cfm race carburetor for $129. Whoever the rebuilder was, was sending out real nice units with well plugs redone and the epoxy never came off, and up number rods and hangers right out of the box.
In another lifetime I had a 1969 SS 427 Impala. It would not go from a standing start. I studied the specs in my Motor book and realized the spring resisting the opening of the vacuum flap was looser for a Corvette. I loosened the tension and suddenly I could set the world on fire from a standing start. 😁
When the Q-Jet is understood and set up properly, they sing. Brass power valves don't go to hell from today's MTBE fuels. The bloke I work with is the carburetor whisperer and has shown some of the methods of dialing a Q-Jet in. Properly done, there will be zero flat spot as the secondaries open and make the passenger soil their Depends... Q-Jets are function over form.
Heavy float will cause some issues!
There are some sneaky ways of setting up a Q-Jet for a given application. They can be highly reliable with proper setup.
"set up properly" That's the issue, They were tuned for application, auto or std, big cam or not, big Ci or not. You need a spring and needle kit that most back yard tuners didn't have. You could take a Holley 780 vac sec off of a 327 and bolt it on a 427 and not change anything. Didn't need to be a carb guru to run them. Maybe a Power Valve change bc your cam but very easy and very little.
850 Mechanical, chop the choke horn off and it's an 890cfm. This is a great video on the Qjet, Thanks to Bill Little and YT for the tips and tricks.
Thank You, it is great to see this carb explained in depth.
The old slide rule guys were smart. It put a man on the moon so why not sort out metering rod selections.
Very informative video, thanks for sharing. First Q jet I worked on was on my buddy's GMC Vandura. Was flooding and spewing black smoke with intermittent stalling. Set the float 3 times.. No difference. 4 th time I took the float out I noticed it to be heavy. Purchased a new float. It was considerably lighter in weight. Installed new float.Set to spec. .. Mission accomplished. Smooth idle, no stalling and no rich, black smoke.The original float was a composite material that had it's coating compromised and soaked up gas like a sponge to the point it was internally saturated. Have worked on several through the years and came to have them become my favorite carb.
Another great episode of Gold's Garage!
The Quadrajet dates to the mid-sixties, it is as if they knew the game was going to change a decade down the road and they created a flexible design to adjust fuel delivery profiles. The design was solid from the start and it needed less to keep it current, it made it to the end of the 1980's for GM.
It is amazing how they juggled and smoothed the transitions to the stages.
It is almost like a CV carb in a rather heavy disguise.
It has been a long time since I used a Quadrajet, last time was in my 1986 C10 shortbox, good fun and yes I admit it, I was a throttle plate driller.
It did idle, smoke the tires and would also pull a trailer, life was good. (-;
The last Q-jet was on the last Olds 307 engines. 1990 according to the internet. SBC already had TBI, I guess.
People like Bill are the last of an elite breed of old school hot rodding.
Great video and I loved the cut-away view. Thank you for making this video and educating so many that the Quadrajet can be a great carb when set up properly = for fuel economy and performance.
I am 70 years old working on cars for 54 years professionally I have been telling people the q-jet is better than a holly all these years
I like quadrajet carbs and this video makes me want to work on some quadrajet carbs to replace my holleys and see what they do.
I have been saying the same thing since the 90s
I love the Q-Jet. some of the hottest cars from the 70s had Q-jets. 455 Buick GSX phase III, which is considered to be the fastest mid-sized muscle car from the 60s and 70s, had a Q-Jet. the Pontiac GTO and Firebirds all had Q-jets. Olds 442 400s and 455 all had a Q-Jets. I have two books on Q-jets. one is from Doug Row and the other is Cliff Ruggles. both are invaluable when tuning Q-jet. Q-jets don't leak around the fuel bowls like a Holley once you get them setup, they just work. the only thing you need to do to a Q-jet is change the fuel filter. I change mine every other time i change the oil. power valves don't blowout. also, there is nothing like the sound of a Q-jet at wide open throttle.
i recently switch from tbi on my 88 3500 454 silverado to edelbrock intake and a q-jet, i rebuilt my first q-jet carb that had been on my shelf for years, on my maiden voyage i traveled 675 miles with no hiccups, i have many other q-jets left to rebuild will be viewing this vid many more times as a guide. thanks for posting this educational program
All of us old guys have had one back in the days.When those secondaries opened up you could definitely hear it 😂.Very good reliable carburetor.Buddy of mine still to this day will not give up on his Quadrajets.All theses old school mechanical tech really does the job.I still run these poor man Muncie transmissions and they hold together under this 550 hp sbc.Stuff was so simple back then.
BEST STREET CARB EVER MADE GET THE BOOK HOW TO MAKE Q JETS WORK EXPLAINS THE CARB
Just looked at the several Qjets collecting dust in my garage with new interest. Glad I didnt throw them away.
I'm glad this video could help you rediscover the Quadrajet! AG
@goldsgarage8236 Thank you for posting unique, useful automotive content.
In my twenties I bought a book on Rochester carburetors and became self taught enough that I did carburetor disassembly and cleaning and overhaul kit parts replacement. In the early 2000’s I did a cleaning and kit parts replacement on an E4MC for my ‘86 Oldsmobile. Come to find out at the time that the air horn casting holes were too small and tight, not allowing the secondary air valve to open. I reamed the two holes with the correct number size drill and assembled the carburetor. What a difference it made even with that Oldsmobile 307 cu in engine when accelerating that Cutlass.
Was that the SA Design edition? If it was that was a great book.
Wow! This is a fantastic clinic on Quadrajet carbs. Well done. My '76 Vette (L-82 motor) had a Quadrajet carb and the car performed well. The engine only made 210 hp but I never had any issue with the carb not functioning well.
Thanks Todd, In 76, it was all the carb the engine needed for sure.AG
I'm always impressed when good power can be made with factory parts. Anybody can buy aftermarket bolt on stuff.
I just happen to have the Rochester book by Doug Roe & Bill Fisher sitting on my coffee table! Pretty sure they recommend drilling out the two secondary passageways, but that book is decades old of course. Back when I worked in a carb shop in Prince George BC, most days I would rebuild at least one Q Jet, many days it was 3 or 4 including the re & re and setup.
Don't forget about Cliff Ruggles.
The main vertical part of the secondary main passageway was not enlarged just deepened. The lower part of the passage was enlarged to the same diameter as the upper. Then you would make a tool to drive the air bleed tubes up a small amount. All this was to eliminate a restriction where the air bleed tube was at where the secondary main passage made a bend and the tube restricted fuel flow. Using Roes book ( by the way he was on the Q-jet design team ) I had my bone stock 300 horse 327 running in the mid 13's back in 1975. I started tuning Q-jets as a side gig after that.
Yup, my cousin was a Quadrajet tuning guru .... when done right, the Qjet is a great performer and street reliable!!!
That was the best and most informative video I’ve ever seen on Quadrajet carbs. Learned a lot. Back in the day I ran one on a Nova and it ran great. Best thing was if you kept you foot out of it you got better gas mileage than a two barrel because the primaries were smaller. The accelerator pumps would wear out kinda fast, but it was an easy fix. Yep always liked them. Worked good.
My cousin rest his soul had a '66 Chevy II Super Sport nova with a 327. He had the art down of keeping the carb tip top. He never bad mouthed the q-jet. He actually called it a quadra-jump.
Personally,I LOVE the Q-Jet! Once you ounderstand HOW it works,and the little quirks,and how to overcome the LITTLE things,it's not only efficient and responsive,but EXCITING when it works!
I’ve been driving Quadra jets for over 50 years. I’ve never had one I couldn’t tune. Love ‘em.
Wow alot of knowledge, love it all. Thank you keeping the old school ways alive.
Awesome AG. You know I would be excited to see this. Bill did a perfect job. The best video on a Quadrajet! Looking forward for more.
I tip my hat off to you Sir. JOB WELL DONE SIR.
Thanks Victory, this is for you Bill.AG
I found in years of drag racing that I could improve my ET with a Q-jet over the 4250 Holley! Once U understand how 2 set it up, It is flawless! Unlike the Holley, which needed tuning thruout the day 4 racing! Keeping a Holley idling properly consistently from day 2 day was also a nuisance! I know all the tricks 4 tuning both 4 maximum performance! The Q-jet is a no fuss all day, every day carb! And it got me .5 - almost a full second on the track! Just by swapping carbs! Great video, guys! Thanx! 👌❤️
That is great feedback, thanks for sharing! AG
Swopping carb brand will NEVER give you almost a second...unless the piece of junk was running wrong in the first place.
Great information. Worked on many quadrajets and they work great once they are tuned right.
I always had great responses from quadrajet carbs
It was the narrow primary barrels that gave it that quick off-idle response. The air moves REALLY fast through those primaries.
No matter what size engine they are bolted to , they will never give more air/fuel than what it needs. They run terrific. Took me a long time to learn this.
That is very true Mark. We see this on the dyno as well.AG
Thank you for sharing this! I was in need of those numbers for the idle circuit! I'm always amazed with the performance of these carbs.
I had a 79 one ton P30 5.7 liter with the Q Jet . I needed more power and better part throttle cruise mileage . With an aftermarket intake , dual exhaust and some tweaks with air bleeds / metering rods I was able to tune to exactly what I wanted . With some advance curve changes and running premium fuel this truck was amazing . Great power on wide open throttle acceleration and a very lean cruise . It was difficult to obtain a selection of metering rods and various parts but fifteen years ago it was still possible . I did sell the truck and for its replacement I went to propane power on a P40 two ton . Operating costs were cut in half even though it was a two ton . But up front costs building a propane engine were high . I finally obtained what I wanted ! Good video ! Thanks !
Good story, thanks for watching and thanks for commenting.AG
Greetings: Great presentation. It is nice 2 know there R still some of us good Rochester guys around. U have my salute and respect. Keep up the good work. Bsafe.
Did a body off only 67 elcamino with a non orig 350 and a 4 speed. Got it with a Qjet, contiplated going the holley route since im comfy with them, but decided on keeping it. Cliffs High Performance happened to be close to me and hooked me up. He put in new shaft bushings, selected all the parts I needed and put it together for me. Threw it on the car and I love it! Feel and sound when those big secondaries open up, love it!
Great comments, thanks for sharing your experience Ganaon.AG
I had a 1970 Chevy truck I bought a 365 horse 327 Corvette engine at a Auction rebuilt it all the way back to stock my Holley carburetor was junk I put a 800cfm Quadra jet off a 1969 ram air 4 400 Pontiac engine man what a difference Carburer stayed that truck ran 13:58 115 mph 3000 stall 4.11 gears Positrac
My best friend in high school... 35 years ago... Had a 78 Z28... The yellow one. 350. And it had a nice exhaust on it and the car sounded great. But when he punched it and those secondaries opened it let out this roar that couldn't be matched. And you suddenly became one with the passenger seat. I don't care what anyone says... When dialed in correctly... The Quadrajet is a Beast!
Thanks for sharing steve.AG
I grew up in the quadra jet era and I use to laugh at my uncle's smacking one with a screwdriver and listen to the idle smooth out 😂😂👍🏼😎
Thanks for the education Bill - nice explanation. Thanks for taking the time to publish this.
Nothing beats a well tuned qjet on a stock or mild build. Qjet works great with AC cars with the fast idle solenoid in HP builds. Only problem with them is people don't know how to tune them.
I remember rebuilding the Q jets in the 80s. I have forgotten all that stuff so this video is great and reminds me of some of that stuff. I'm glad I still have one Qjet left, just have to find it somewhere to use on a BBC
Greetings: I know a few people across the country that know Rochesters well. Others claim they know yet cannot prove it. Historical experiences have proven my knowledge, skill and proficiency. Me, not being authority, however I recognize knowledge and skill. I add this man 2 my list of yhe rare, few and knowledgeable. Good job sir. My compliments. Bsafe. Thx 4 the share.
Thanks, this was very interesting. Reading a book on things to do to a carb doesn't match up with what Bill explained. I an anxious to see him work a Q-Jet into a race carb.
I had the pleasure of rebuilding many of these carbs back in the day; when set up correctly, they can’t be beat!
I agree, they are great if you know what you’re doing! AG
I'm 62 and learned how to properly rebuild QJs by a guy named Jesse at Carbco in Lemay Mo. Way back in the early 1980s. I even rebuilt my 62 Olds 88 square bore QJ.
Thanks Dave, great comment.AG
I have modified many of these in the past for circle track and street use. They can be very dynamic and near bullet proof.
From the voice of experience. Thanks Mike.AG
If you call Quadrajet carbs junk, you dont understand carburetors in general. The shortcomings are pretty minimal.
I once built myself a gas miser, had a 120 mile round trip to work everyday. I used a 1984 190hp L-69 305 from a Z-28. Did a basically stock rebuild on it, .030 flatops, cleaned up 416 iron heads with Manley replacement valves. 1.84/1.50. Nice valvejob and .012 milled off. Used the old GM "Z-28" springs, Comp roller rockers, a Comp 260 HE flat tappet cam, Edelbrock Q-jet pattern performer intake, old 1970s 4165 Holley 650cfm vacuum secondary carb, HEI distributor and 1 5/8 primary, 3 in collector Hooker headers. Backed up with a basicly stock rebuilt 200R4 trans and a 3-42 gear & Eaton posi. It was in a 1985 Pontiac Gran Prix. That car got 30+mpg on the highway and 25+mpg in town. And it would do 300ft smokey burnouts on 275/60/15 street tires. Looked good, sounded good, and it got extremely good MPG. And as a bonus it ran pretty good too. It was a low 14 second 1/4 mile car. Real good work car if ya gotta go far. Later on it ended up with a 600+hp 385ci sbc, T400/5000 stall, & a 12-bolt swap with a 4-88 gear. It evolved over the years. But the first build on it was all about how many mpg I could get out of it. It ended up as a drag car that got trailered to the track. But I was always impressed with how well that Q-jet replacement Holley 650 vac sec 4165 carb worked. Real good street carb in my experience with one. I like the Q-jets too. Built plenty of those as well. Good carb for many applications.
Lots of good info in your comment, and good to hear from you again. Thanks Gearhead.AG
I rebuilt my first Quadra-Jet on my Dad's 67 327 Chevy pick up when I was 15.....it was scary, but I didn't have any pieces left over and it ran great! He was shocked!😂
Sounds like a great learning experience! AG
Excellent info, I epoxyed the fuel wells that would leak and learned how to adjust the secondary baseplate screw, i made a small screwdriver to use upside down. I had a holley 6210 that the transfer tube would leak and preffered the q-jet to the holley.
did the well plugs leak after while gas will eat the epoxy al the info i looked up said yes put a holley in its place it really woke the car up set the tv cable up alse
@@dewwed1551 I didnt have any issues with gas eating the epoxy, however that was in new orleans in 1985-1992, gas may be different now on epoxy repairs, the way i knew the wells were leaking, was after i shut off the engine, vapor would come out the carb, and it was hard to start after sitting. Which holley carb did you go with? back in the day, q-jet manifolds prevented us from using square bore carbs, without afdapters. good luck youngblood
hey mike i watched a vidieo 2/3 yrs ago and that was the problem they even put threads and plugs with ep and after while they said it would leak i like my q jet but have to say the holly woke the car up did put the tv cable adapter on i hope the leaking can be fixed thx
It's funny how this popped on my feed a day after I thought about Quadra-jets for some unknown reason. I had one on my 360 Chrysler. Pretty ingenious, using the primary venturi vacuum to open the humongous secondaries instead of a mechanical linkage and needing an accelerator pump. WAY more logical than the original four barrel carbs.
All good points, thanks for commenting.AG
One really important info note always check top when off for straightness /flat I have rebuilt many and have found most to be warped from over tighting the long bolts to much.
Thanks for the tip Greg. AG
When he says Holly is uncomplicated who is he kidding. I have never had one but many Quader jets and they are by far the easiest to work on. One thing to remember is the Carburetor the Quadre jet replaced was an absolute nightmare with linkage going everywhere all needing adjustment to work properly. I had an owner once who called me Mr. Carburetor because I did so many.
The truth be known I did hundreds that didn't really need it when all was said and done but it satisfied the customer and paid me well.
I can tell you I never had one I had to modify with those rods into the secondary jets or anything else. the biggest problem was the plugs in the bottom leaking gas into the manifold fixed with two part sealer so they couldn't leak.
I started working on Mercruiser inboard and blue-water inboards in 1978, and attended the Mercury Marine schools at Auburn, Mass and East Brunswick NJ. Always loved the Rochester carbs, both the Quadrajet and the two-barrels, because we never had to touch them unless the boat had sunk or caught fire. We'd flush the engines, change the oil, add antifreeze to the blocks, pull the drives, and park them in the sheds. Never drained the fuel systems, and they fired right up next sprin. I had two stern-drive units that ran 15 seasons in salt water with nothing but standard maintenance, never touching the carbs, until they both needed valve jobs. If I got a sinker, I'd pull the carb, strip and clean it, install a new brass float, and reinstall. I have a Mercruiser Quadrajet off a 260hp SBC 350 I-O that the owner replaced with a throttle body injection unit, and will run it on my 1975 Plymouth Duster 360 instead of the Thermoquad. Thanks for the info!
That’s a great story, thanks for sharing Bruce. AG!
Always preferred the rochesters over the holleys. Rochesters were a fuel metering device and the holleys were a fuel dumping device.
You mean the myth of the little guy under the hood with a VP fuel can pouring fuel down the carb is true?? 😮
@@Sunspot-19 I mean the Rochester was a more economic carby to run and smoother transition through the throttle positioning, were the holley was better for raw horsepower, foot flat to the floor.
I totally agree with you about the quadrajet, it's an awesome carburator and I NEVER had any problems with mine in a big block Buick, or my brother's Stage 1 , his NEVER gave any trouble at all, and we drove the crap out of those cars for years!
Thanks for sharing your experience Kim. AG
Quadrajet is a good design. The problem with the Quadrajet carbs is finding tuning information and components. Their design is similar to the Carter carbs but with the exagerated stead bore design. Once you get one set up correctly they seem to keep their tune better than Holleys. Just my experience as a 30 year mechanic.
Good to hear from you Dale and thanks for sharing your experience.AG
My Dad loves the Quad. He installed the same Quad on several 63 Split windows, and even kept the one installed on a 210 1955 before it left his garage. He always said, "Ignorance is no excuse."
Thanks Tony, your dad is right on!.AG
Great carbs. My 86 GMC came with one on its 4.3v6. Im now running a crate 350 with a factory 395 roller cam and the Qjet still performs flawlessly.
I always liked the q-jets. We used to say there only 2 problems with the holleys. Getting them running, and keeping them running.
Thanks for your comments Dogboy.AG
i always liked a quadrajet carbureteur on the older cars flip the breather top upside down it would moan i read that the the rods that goes through the side of the carb that has the rubber seals would wear out sucking air would make you think you had a vacuum leak !!! good informational video you could put bigger jets for more power good job men !
Need to do a video on the thermal quad even more misunderstood then the Quadra jet and was actually a improved version of the Quadra jet kinda of a blend of the Carter AFB and Quadra jet in one carb.
Thanks for the suggestion Bob. We will get to it eventually. AG
I still use a Quadrajet on my 77’ K10.
It works well in the cold, but sometimes the choke doesn’t sit where it should or sometimes it doesn’t release off the fast idle cam.
I need to give it a good cleaning and add some powdered graphite to all the linkages and moving parts to get at 100% again.
I make sure to run non-ethanol fuel to minimize the fuel evaporation out of the bowl and it usually starts pretty quickly as long as it hasn’t sat for over a week.
The first three cars I owned after I got my license were all Oldsmobile 442's, a 68, a 70 and then another 68 and of course they all had Q-Jets. The first 68 at idle, would pretty consistantly mis-fire on random cylinders, but would drive down the road pretty well, at least until you floored it! Then it would just fall on its face for a couple seconds before it would start taking off! Luckily for me my neighbor was a Q-Jet fan and helped me rebuild mine and showed me lots of tips on making them work correctly. That car ran so nice after the rebuild, no more misses from fuel dripping in the carb bores and no bog when you punched it after fixing the problems with the secodary air valve, now when hit it, it just went! After that I never even considered running any other carb on my Oldsmobiles. Another carb I liked because it always worked so well, but only had experience with one of them, was on a friends 70 Dodge Dart Swinger 340, it was a Carter AVS. Has anyone else had experience with them, and did they like them too? Thanks for the great video! I still have a few Q-Jets around, I just wish I had something to put them on!
And thank you K for sharing, great storey.AG
I hung out with car racers on Sundays in the early seventies, in New Jersey, who ran a 68 Camaro 396 wedge motor automatic in Super Stock. They had a Q-Jet on it they said ran as good as a Holley. Q-Jets leaked after a few years, but so did Holleys. Just tightening up some screws solved the problem with both. You can change jets in both carbs. You could change the rods in the Q-Jet secondaries. You can change the Q-jet secondary flaps opening by bending a tab. The Q-Jet could be modified to do anything you wanted it to do. And they were cheap. And you could buy a mod kit from your local hot rod store with an assortment of jets and rods. I texted this before the video began.
I agree, if you know how to tune them, they can be great! AG
Good show AG, thanks Bill. 👍👍👍
You are one of the few that knows the qjet. I can only add the stock fuel filter can be restrictive. And use an external one and leave the carb one out. Also the hole in the carb body and or the fuel filter housing can be more restrictive than the needle seat. The fuel pump plunger spring and the accelerator pump jets also can be tuned. Keeping the float low can limit the amount the needle opens and can create more of a problem than sloshing. Maintaining fuel pressure is important on high hp cars as a these can pass a lot of fuel. Use on engines over a real 450 hp they need to be built right and i’m sure you build them right for the application. Well done.
I always pitched the stock filter and opened up the carb body hole too. I also found that leaving the float level alone and taking precautions to deal with sloshing worked better than lowering the level. Great additional info.
In Raleigh there was a black man that ran a shop near Ray Price Harley Davidsons dealership. He NEVER advertised but everyone knew if you wanted your Quadrajet to operate at PEAK he was the man. My 76 Malibu with stock intake and manifold ran rings around my friends 74 Malibu. He was using a brand new Holley 4 barrel intake, Holley Carburetor, and Headers. He could never keep up!
That's an awesome story, thanks for sharing! AG
Q-Jets are awesome!!! Built many of them, 22 years in the auto repair business, the ones with the forward facing fuel inlet are Pontiac, Buick and Olds, I put them on everything
You’ve got a lot of experience with these carbs! That’s a great tip. AG
Holleys are getting expensive.I'm looking into putting the quadrajet back on my camaro.After watching your video I'm convinced.Thanks for the great information on these Q-jets.
Thanks Mike, glad it was helpful.AG
ran a qjet on my '74 Buick455,ran great,really helped when I installed a stage1 fuel pump with a 1/4 return line back to the tank pulled 14.8 in the quater mile bone stock 8:5 compression,cheater slicks and variable pitch T400,2200 stall
That's an impressive time, considering you're bone stock! I bet you're having a blast with it.AG
Single biggest issue with tuning these is the parts availability. Edelbrock carried some for when they were manufacturing them, but to find a set of primary metering rods or primary jets in a typical town is virtually impossible.
Thanks Yarrda. I know what you mean - you can't just pick up a set at any parts store.AG
Yes sir carburetors can be a tricky wheel. I myself prefer a Rochester carburetor for a stock application. Like most people I might prefer a Holley for performance applications, but for the reliability and simple operation I think a Rochester unit fills the bill. However, I have run into people who know more about the modifications that can be done to Rochester carburetors to have them perform better. Always learning things about carburetors, they are really engineered and most of us do not understand that engineering but this video helps unlock what is done here and also helps one to understand the workings of the carburetor.🥸👍👍👍👍👍👍
Great comments, thanks Billy.AG
@@goldsgarage8236 Welcome
Absolutely LOVE the sound of the Quadra jet as it starts with the secondaries and boots down to the primaries! Magic!
Thanks Sandy, I remember it well. AG
I've learned a lot from this. Thank You for sharing your skills with us.
Thanks! I am glad you found it useful. AG
I used to race with a Quadrajet. So easy to tune at the track. Don't have to worry about gaskets leaking. No power valve to leak. The Carter AVS was a good carb, but not as big. Tried running a Holley, but never ran as good. I think I still have a few Quadrajets stashed someplace.
good comments. Thanks for watching and commenting Sandy. AG
There's nothing like the sound of a Quadrajet when the secondaries open up.
@@russellkeeling4387 It is a sweet sound.
For sure, tnaks for commenting Russel.AG
Really liked what Bill said about the Mercruiser Q-jet secondary door, open it up for 20 more horsepower and charge you extra for that!
I used to go car-by-car in Pick Ur Part yards in the 80s to collect metering rods and hangers from Q-Jets. I had quite a collection back then. My 69 Firebird had a built 455. I was able to contact an old engineer at GM who actually provided me with the build specs for the Q-Jets from the performance 400s and 455s on the Pontiacs back in the 70s. Could practically duplicate them. It was easy to find the larger Q-Jets back then.
That is some great information. Thanks for sharing! AG
You were lucky to speak to an engineer from Rochester, many smart people who are forgotten, thanks
Qjet is my favorite, t-quad is my 2nd favorite.
The Quadrajet is really a excellent carb! especially for mild to moderately built street performance engines. Sadly it is also a very misunderstood carburetor. that buwhaa sound when the secondaries open they make, through a low restriction air cleaner along with that nice high torque acceleration rate is super cool too! set them up right and you get easy starts, decent gas mileage and strong, great reliable performance.
All good points, thanks for commenting.AG
Good to see Bill's doing well! He built the TH400 for my ride. Still going strong 20 years later. Great vid!
Sounds like Bill did a great job! Glad to hear your ride is still going strong! AG
@@goldsgarage8236 Not only did he do a great job, he took the time to have me in the shop and go over the problems with the trans and also explain how he was modifying it for racing abuse. I'll have to drop by and see Bill. He's a great guy and I lost contact with him when his Belmont location closed up.
Thia was some great information! I learned a few thing today on these carbs. I have been messing with my 800 cfm Qjet for my 502 big block and I cant wait to get out there and try some mods. THANK YOU FOR THE VID!
I'm a Qjet fan, thanks for the vid, looking forward to part-2.
Glad you enjoyed it, thanks for commenting.AG
I've owned a few autos with Quadrajet carbs. I never was a fan of Holley carbs. The only problem I've had with the Quads is warping of the base. After the first time I learned how to recognize when it warped and would take it off and mill it back flat and it would work perfecting. That only happen on one vehicle which was a 1966 Impala SS 396.
Thanks for sharing your experience Russle.AG
I like the durability of the Quadrajet but the Holley dual accelerator pump 4 barrel with it's mechanical secondaries was always easy to tune so that was my race carburetor in the years before their metering blocks started warping all the time. Then, and to this day, I chose the Edelbrock AFB design carburetor.
I have an old friend that used to drag race a 67 Beaumont with a 327, he was always known as Carter Ken. His car ran 10.70s at Ashcroft!
The AFB is a Carter carb.. and there was the WCFB by Carter... Edelbrock brought the AFB back from the dead..
@@tonysendrick6347 Yes
To my knowledge, I’m a Ford guy, there were good or bad, the Pontiac that I drove had one, never had a problem. Much, much later, after learning more about carbs, I now wish to bolt one on my Jeep, that has a 4.7 Stroker.
The Q-jet should work fine on your Jeep. Thanks Otis.AG
Thanks Craig, my apology about getting your name mixed up on my reply.AG
Secondary opening rate is actually controlled by the vacuum pull off more than the spring tension adjustment is secondary to it. Early first Gen Quad had a slow 2.5 second opening rate and the rod connected to those flaps means regardless of how much engine pull or rpm is under it , it still takes ,2.5 seconds to allow it to fully open then in 70s they started changing the vacuum pull off to 1.0 seconds start to finish of letting the flap wide open and what ya really want. Eliminated bog of a broken one but opens quick enough to be just as quick on the track as any Holley and as discussed will support 9 second 1/4 n/a drag cars. I have gone 6 sec 1/8 with mine
I was always a Quadrajet fan. Never got along with the Holley and those power valves . I like the yhe Cafillac quad thas has the adjustable mid throttle screw.
I forgot the one thing with Quadrajets is that they were individually set for each engine they came on so just swapping them around didn't always work out so well . Look for the ones with the external metering adjust. Gives you that extra bit of tuning.
You mean the adjustment the service manual says to never adjust!
@gordonborsboom7460 Well of course , the super secret one the EPA hides lol.
I ran nothing but "Q-Jets" back in the day. I had 2 that didn't work right and both were very simple mistakes that I MADE and were EASILY corrected. I thought Quadrajets were terrific, and as we all know, sounded fantastic when the secondaries opened. I don't recall anyone who didn't run around with their factory air filter lid flipped over to hear that sound.
As 16 year old kid, that's the first thing I did, well after I put a 4 BBL QJet on a 283 Impala that really didn't need it, my dad thought I was nuts!!.....maybe I am still lol
@@billlittle4285 I had a '79 Camaro with a 305 "Duojet." I swapped to an aluminum 4 barrel manifold and a Qjet. Sounded good, but at times smoked like a diesel. WAY too much fuel! People asked why I did it. Easy, the parts were free!
I've watched this three times so far to take notes. I've read Cliff's book and Bill does a great job explaining the concepts.
Everybody says they’re the worst carburetor made. I found out those people don’t know how to adjust the upper plate on the secondaries. One simple thing leads so many people down the road of throwing them out and giving up.
I love the quadrazeñ it always works great
Good points, thanks Max. AG
I’m sure there are some fast stock eliminator and super stockers using that Q jet.
It was a great carburetor you had the follow all the adjustments once they were set it worked perfectly. They didn't like dirt they didn't like dirty fuel filters.
I agree, it was a great carb if you kept it clean and tuned.AG
I still have the rebuild manual's for Qjet's etc..,i. rebuild several and replaced it with Holley 650 Spreadbore which i had no problem swapping jets and rebuilding back then.
can't beat the sound of the secondaries opening
pretty cool, for sure. Thanks Buddy. AG
I had the famous Q-jet model 4MV on my 396 Chevelle... and later I put it on my de-stroked 396 Nova... Awesome carb
The Quadrajet allways beats a holley on the streets! AFB's do to and are easier to tune!
Thanks Wayne.AG