I receive a lot of questions about this subject, so in this video, I explain several issues that could cause the secondary side of a Rochester Quadrajet to become non-functional.
I am a QJ guy from way back (I'm 63 years old). My Dad became an expert on the QJ in the 60s and taught me many of the great things you have in your videos. I learned from him on our 62 Impala Wagon when we rebuilt the QJ (he did, I held the light). Today, so many young men slam the QJ and call them "Q Junk". I try to leave comments about how the QJ is the greatest Carb ever invented and is Americas "Weber". Recently I watched a video by a Jackass with a popular RU-vid channel called "junkyarddigs". He acquired a 72 Cutless that is a time capsule dream car for anyone that loves cars. He is not stupid, just a jackass. He purchased it, got it going, and drove it hundreds of miles home. Once home he rips the QJ off, throws it in a trash can ("Qjunk"), and then proceeds to take a hammer and chisel to the factory intake so he can fit some aftermarket carb. I gave lots of ignored input to the channel. The QJs are complicated but infinitely adjustable. They get a bad rap because people simply will not take the time to understand them. How do these kids think the corner hot rod shop knows more than all the floors of engineers at GM? You said it correctly, a factory application of a QJ is as close to fuel injection that is possible with a carb. The best economy on the primaries with all you could want on the secondaries. And, since the seconds are vacuum operated they adjust for engine age. Brilliant! Please continue your teachings on the QJ. I have one on my 1985 Chevy K20 with 350 M series. The most amazing thing is that I purchased it new in CA and due to some CA loophole (8600 GVW, tow package, auto, 4X4, M series engine) it has no catalytic converters and no computer/computer control of the spark or QJ. I love my old truck!!
Well I’m glad to hear the qjs are complicated because it’s my first carb I’ve dealt with on a car and to add to the fact, it’s a Buick 3.8 turbo which has a lot more vacuum lines and what not. Still trying to get it right.
@@Farmerboy5 There is an outstanding book (I loaned my copy out and never got it back) dedicated to the QJ. When I remember the name I will suggest it.
I've been running the same Quadrajet on my 81 Silverado for 13 years, and it still works just fine. Many years ago you explained how to adjust the two mixture screws on the front, and _then_ adjust the idle speed screw. I did just as you explained, and got excellent results, that cleared up a rich running issue. Thanks for another good video on these, I appreciate it.
Just an excellent explanation of the QJ, these are really really great carburetors, I'm only 35, been building cars since I was about 10 yrs old with my grandfather, father and uncles. I learned very quickly that these are by far the absolute best option for economy and performance when tuned correctly and not butchered. You can also pick them up for a reasonable price if you can find ones that haven't been absolutely cocked up by some smooth brain.
This is BY FAR the best Q-jet video I have seen. You actually know what you are talking about and discourage people from modifying a good design. One suggestion is a video that demonstrates how to properly set the choke on a Q-jet, including detailed factory instructions on how to properly set the primary and secondary pull off mechanisms so they work properly. I am still struggling on getting mine properly adjusted on my 455 Trans Am. I cannot find a good video on this subject. Thanks.
I appreciate all of your Quadrajet videos. Invaluable knowledge from experience for those that want to understand them better and run them on a regular basis.
Hello Tyler, I always enjoy your videos, especially your quadrajet videos. Almost everyone I've met that hates them and said they never worked right is as a result of them messing with it and never understanding that they weren't meant to be played with. Like you said there's nothing like a properly set up rebuilt q-jet 👍 It's always a pleasure watching your videos. If people just took the time to listen they would learn a lot.
I rebuilt a q jet for a 1983 Apollo 3300db with a 454 on board, it used to run very poorly due to dropped pickup tubes, a bad accelerator pump, and a clogged fuel filter, but once I got everything worked out, this rv has some real buck to it. Anybody who says q jets bog should listen to this rv, no bog whatsoever, silky smooth transition to power mode for merging and passing hondas.
I have watched your past videos, and when you called it a dampener. But, dampener is actually the best description for the action of the vacuum break. The vacuum break is doing a double duty, First by controlling the choke plate (butterflies) and then double as a dampener on the secondary air doors (upper butterflies). What many back yard mechanics and believe it or not professional mechanics don’t understand that the rear air doors (upper butterflies) function is basically a mechanical mass air flow sensor. The rear upper butterflies (air doors) functions as a sensor plate that it’s actions articulate the cam the metering rod holder via a rocker arm action that lifts the metering rod’s. Furthermore, thus the metering rod’s regulation fuel progressively as the air doors open via the increase of engine vacuum signal. One more thing, love your video’s...👍
Thanks for this, I learned a lot. I watched this because my son just got ‘78 Blazer with a Summit Racing 454 with a Quadrajet that has been driven very little for quite a few years. It runs great when it does but it only runs for about 15 mins or so then stalls, idling or on the road during a test drive. Probably haven’t gotten over 50mph and only for a few seconds, mostly cruising about 40mph. I tried adjusting the 2 front screws per instructions I read, with the engine warmed up, in all the way in then out 2.5 turns. The 2nd part with the engine running, in until it runs rough then out til it runs rough, then back in half as many turns, on both screws. That didn’t work so well so it put it back to 2.5 turns out from all the way in. That seems to run best but It still stalls after about 10-15 mins. The last time it stalled and we got it started again, it backfired through the carb once then fired right up. I haven’t worked on these old pre computer cars for a long time and complicated carbs were never my thing. If you have any suggestions we would greatly appreciate it. We’re wanting to avoid trying to find a mechanic that knows these carbs, but don’t want to take up too much of your time either. Sounds like you would no pretty quick what the issue is.
You have the best and most informative videos. I just got a rebuild kit for my 71 C25. Now I need to go back and find what video is best for that rebuild.
GR8 on covering the secondary side enrichment. On the HP they made some slots on the butterflies so they could kick in sooner. I have drilled mine out a bit don't take much to get to large. About the size of a WD-40 spray straw is way to big. Most are counter sunk about 1/2 way to make them look large.
Those doors over the secondary throttle valves are called secondary air valves. The diaphragms that hold them closed at idle actually control the opening rate by means of an specific orifice in the vacuum nipple connection. Some guys who run high performance engines (cammed up with high flowing heads) need to have the air valves to open faster than was available from the factory. They drill out the orifice to a larger size then experiment with different size orifices that are placed in the vacuum line going to the vacuum diaphragm. Kind of time consuming but works. The Carter thermoquad works the same way.
Thanks a bunch . I learned a lot . . You seem like the good ol boy professor ! I have a 78 p30 step van I work out of . So been trying to keep it alive . It has a great Jasper 4 bolt main 350 in it and a remanned quadrajet that is probably 20 plus years old . Just had some vac leaks hoses I fixed and discovered the choke pull off was not working . So I replaced it . But then realized that years ago when I put a manual choke cable on it that the pull off no longer does anything . The hand choke is working pretty well , but thinking of going back to the spring type choke accuator that sits on the intake manifold I. guess the spring lets the choke pull off function the way it is supposed to [ because it has a spring not a solid connection to the front choke plate linkage . . So It might be better that way . Otherwise it is just a matter of me remembering to push the manual check knob al the way to the full off position . I don't remember now why I went to a hand choke in the first place . I do have a bog when I step down getting on the freeway , so maybe this new one I just got from Guaranteed Carburetors won't do that . From what you say it will be critical to have he choke adjusted just right . I think you use a certain size drill bit in the horn to keep the front choke plate open just a bit when it is in full choke mode .I think that is the only adjustment available on whatever kind of choke you have on these . And that is just done by bending the linkage rod running up to the front choke plate as I recall . Not exactly high tech . But you say the QJ is the closest thing to fuel injection . I guess maybe I should adjust the idle jets and idle speed on this new one .I guess I should connect a vac guage to manifold vac to adjust the jets ?. Anyway I will subscribe to you channel for sure .
I always disconnect the secondary choke braek. It bleeds down very slowly, to keep you from wasting gas when you pop up in the secondary. You can adjust the secondary air valve tension screw underneath, the small Allen key is underneath
I HAVE seen the vacuum pull-offs go bad and have replaced a few over the years (decades). The rubber diaphragm can either develop a hole or become cracked around the outside edge causing 2 things. 1) vacuum leak 2) no pull action to help open the primary choke plate.
Mine was bad in the dual jet I could suck vacuum on the one side and it would slowly release back so the insides must have rotted Very hard start and once it was running the choke plate would close and totally flood it out
Change the $16 transmission modulator valve first it takes 5 minutes. Now my secondaries open up perfectly when I step on it hard, and it kicks down to 2nd gear on a 1989 motorhome Chevy 454 with a hydromatic 400 tyranny. Cheap and EASY fix. 💣
I just picked up a GMC c class 30 van, and there's a quadra jet in it but parts are missing i.e. butterflies for second stage, I think the down tubes ( friggin praying they were not dropped into intake manifolds and so forth 😵) anyhow thanks for the refresher it's been way to long and yup frustrated as hell, the nightmares on foolish hack job repairs just keep coming one right after the other ! Anyhow the vids are helping out dust of the memories but have forgotten sooo much info lol wife calls it sometimes disease, sometimes I remember sometimes I don't, and some times 😉😉 well you get it 🤣🤣 anyhow thanks again gotta go hobble to check out some info in van ( twisted knee dropping and moving 3/4 full rotten gas in tank 🤢🤢)
If the Qjet is a 1976 off a 500 Eldorado and has an electric choke, but no wire connected, will that keep the secondary throttle plates locked out?!? I’m not sure my secondary is opening up as it doesn’t get noisy. Sitting on the bench the choke is closed, on the car is it going to open all the way with no wire attached? Thanks for the great content and explaining the vacuum breaks and some of the circuitry, it was a big help. Also now I know my vacuum advance is connected to ported vacuum which is incorrect! Thanks!
Thanks Tyler for all your quadrajet vids i live in England UK and own a 83 c10 305….which over here are like rockin horse shit not to mention spares which i get from rock auto the shipping costs are horendous….but on a positive note i re built the 4bbl quadrajet under your guidance and truck drives like new👍👍many thanks 🇬🇧🇺🇸🇬🇧🇺🇸🇬🇧🇺🇸🇬🇧🇺🇸🇬🇧
Now I'm worried. I have a small town mechanic that says I should replace my quadrajet with an Edelbrock on my '79 t/a with 403. I think it has a choke problem and you've described it.
Did you switch to the edelbrock? The Rochester is better. I learned how to play with the Rochester, and it’s better than an edelbrock. The edelbrock will bolt on and run but it will never be as perfect as a Rochester. If the Rochester came with the vehicle, I’d do a complete overhaul on it and change nothing. The overhaul may require shaft bushings. Normally that’s the problem. It causes a vacuum leak.
@@ericharris893 Car still in storage and going to have a guy that works at a marina look at it. He's the only person I found that can work on and rebuild a quadrajet. By my description, he just thinks I may only need some minor things done. I'm hoping for the best. Probably have him stop by next month.
I got onto the Q-jets when I bought a mid 80s dodge van that had one. I thought that someone had cobbled it up to work in place of a thermoquad but later found out that in 85 Dodge van & trucks had to use the Q-jet because Carter got out of the carburetor business due to the looming fuel injection revolution. They used the Q-jet from 85 through 88 on the 360 engine. Just some trivia. Currently I have an 88 Class-B camper that has one and I intentionally located 2 spares (just in case). Great carb, efficient, good low speed throttle response very similar to FI. All the Dodge Q-jets that I have located have the small primary venturii. The chevy Q-jets that I have stashed have primary venturiis of different sizes. A 305 carb might have small venturiis then the next 305 carb might have large primaries. Doesn't seem to have anything standard. Most 350 carbs all have the large venturiis. This is on the 80s era Q-jets that is. I don't have very many that are from the late 60s or early 70s.
Right on. That was the second time Chrysler used a Rochester carb. The first was in 1971 when Carter could not produce enough 2bbl carbs for the 318 and they used Rochester 2G carbs for a while.
100 💯 % right !! Saw a show were they took the latest greatest quick fuel 750 of engine put the original q jet carb back on exact same horsepower on the dyno go figuire .
Thank you for your videos, I'm very new to Qjets. I have 1985 pontiac TA with the 305. It is computer controlled with the TPS and the MCS connectors. The fuel inlet/filter faces the passenger side on mine. Any techniques for cleaning and lubricating this carb? I am the 2nd owner and the carb and car itself is all factory, about 66K on it now. I have not watched all your videos yet,, so if you covered this already just let me know what video to watch. Thanks. Also has the electric choke that is riveted, and only has the forward choke pullout, but seems to run ok, I think this car sat for awhile, it didn't come with any service records. Thanks again.
Have RV with 454 and quad. Jet. Vacumn is through the roof maxed when I try to get secondary to kick in any quick advice or vacumn leak likely issue and choke is not releasing secondary as you pointed out in the video. Help appreciated
Hey Tyler, have a question. My Qjet on my 1980 impala 454swap isn’t opening as they should. I took and unplugged and blocked off the vacuum to the choke hold down on the back barrel. They open fine and the car kicks as it should. But I don’t like it like that due to no choke on cold start
I have a motorcraft 4300D which is just like this. I removed the secondary lock out and converted to a manual choke. I’m get the thing about not messing around, but it was causing me problems and It is a simpler system than this thing.
The secondaries will only open when the engine demands the airflow when the RPM's are around 4,000 RPM. Only if you are running a 750 on big block the secondaries will ever see the secondaries more than 75-80% open since most engines will never demand max airflow from a Qjet.
Man I can’t get enough of these Quadra-vids!!! Now that you told us all the things not to do how about some of the changes you can do to these things, if there is any, to make them “better” or perform a certain specific way that they originally were not meant to... is there any? Anyways thanks again my dual jet or duojet whatever it’s called is working much better now thanks to your info. Also what is the name of that Quadra jet book you talked of??? I want it.
The thing with q-jets is that they aren't designed to be messed with. Of course if you don't have a computer controlled version and you have an older Q-JET you can buy larger jets and different sized needs and modify the secondaries but it's a rabbit hole endeavor that will always leave you with running issues and scratching your head for why your not getting the performance you wanted out of it. Remember this,... Even if the q-jet was designed to be adjusted for performance applications you would still have other issues to consider such as intake runner size and volume for the additional fuel, as well as cylinder head considerations for volume and compression. Watch a few more of Tyler's older videos on q-jets. He explains very well that no matter how much you try to modify a q-jet you will always have problems and eventually throw off the ideal meeting and balance of air to fuel in such a way that it will actually hurt performance. Keep it clean, keep it stock, and keep it runnin!
Check out Cliff Ruggles, he has a few books on q-jet rebuilding and troubleshooting. He also has a website where you can buy parts and tools for doing the job. I've spoken and purchased kits from him and he's a wealth of knowledge in q-jets. Look him up. He's well respected in this field.
Eric Pratt ahh ok I agree with leave them alone just figured if there was anything that could be done would be cool to watch. Thanks for the book reference I want to be a guy that can fix these things it’s a lost art!! And I have watched all his qjet videos haha I love em
Very good video! I need some advice on something. I recently bought an 1986 chevy truck with a V6 4.3. It has a propane system on it and the original carburetor is no where to be found. I have a 78 quadrajet that I just rebuilt and would like to install it. the truck intake manifold is the original four barrel spreadbore quadrajet carburetor set up. Also this engine has the electronic spark control distributor without the vaccum advance. if I put this 78 carb I got on it do you think it will work just fine?
My air doors move, but right after the start there is a point where it feels like it catches, it only takes a slight bit more pressure to open and once past that point it is smooth as silk. Any advice onnwjat to check? Maybe the cam for the secondary metering rod lifter?
I have the same carb has the hot air choke port but its plugged and it has an electric choke on it can this be why its not working properly? I have had nothing but problems with it. Have to use starting fluid to get it running.
Local Joe In the backyard With his screwdriver And his pliers And his side-cutters You know him too? It seems he got to every single used vehicle I've ever bought.
for the second one where do you get the vacuum source? the front one I have figured out on my 1985 gen4 454 but I cant figure out the second one thats on the back closer to where the break boots hooks up
I bought a "new" quad awhile back. I didn't notice right off that the secondary was not kicking in. Not until I hooked up my trailer. Mechanically they don't work. The throttle part doesn't have away to move the secondary part. At the moment I got a zip tie hooking them together. Works half ass. How do you fix it right???
Hi, I have a 1984 C10 305 V8 Original, Cast Iron Intake, Electric choke, small metal line comes off the exhaust below the exhaust manifold for helping warm up engine( when cold closes when hot opens) works off vacuum on exhaust on passenger side. Has EGR Valve on cast Iron intake, but I have Removed smog control. Will it be safe or important to close off the heat cross over on this cast iron intake before reinstalling? Will this help the QJet not get to hot with now days gas. Thanks for info
cut the secondary lockout arm and replace the secondary rod (with a shorty)that opens the secondary at 35 percent and the party starts early,Woohooooooooo!!!!!!
i got a qjet that runs great at idle... but seems to lean out just as i press the gas. sometimes it backfires... some times it just bogs... some times it dies. if it stay running and catches up, it climbs up like its supposed to . I looked down the primary and can see the pump squiring gas when the throttle is opened. any advice?
This is my problem. I went to replace the needle float seat on a 79 quadrajet, There was a washer(gasket) that came out. But there looks like there might be another gasket. But it looks like it may be part of the carburetor. When I tried to get it out, it doesn't move at all. It feels like it's metal but darker in color than the carb. metal. I just don't want to dig it out and maybe damage something. Your thoughts please. PS. Great videos. Thanks
Hello Tyler I have a 1976 corvette with a th350 transmission that will not move in reverse I checked the fluid and change the filter still no reverse any suggestions ?
good morning, i have a quadrajet from a 1976 454 it uses a different style of pull off, are there any updates i can do or just have to find that style again
Love the video ? Qick questions I have a 1985 Pontiac 305 4bb Qjet . Ok carb seams to work fine ideal n kicks down all good thing is after car is at running temp I do a couple of burn off pulls n car stalls u think Qjet has an issue? Also if I turn it on and not fully let it warm up I shut it off and it dieseling n clunks would u know y? Any theories Thanx ..
My god I've found out the one thing I've been looking for I race circle track and we have to use this carb I'm a good chassis guy went Way way up the ladder years back 56 now and playing with lower divisions helping young guys go fast there's a guy who started in this class for beginners who was from the north nobody knew anything about him man he could jump 3 car lignths on restarts had massive power coming out of the corners come to find out he was a quadrajet guru our engines and transmissions rearend were checked and sealed by track officials I figured it out what his advantage was the tunning had to be it the upper holes on the back flaps are lot bigger than any I've seen someone else said he made it full time 4 berral by changing the linkage I've got to try and figure out how he is getting such an advantage we all run same camshaft set heads up so I'm thinking about drilling the secondary enrichment holes bigger a little at a time we gonna catch him
I have a rv and I spray starting fluid in to it and no start my question is if my choke or float or needle /jet messed up. Will it start with the ether! I spray it and it doesn't even act any different. ! Wants to but no start
im in ..got an 800 front spout fuel line p b o ..cadi ? well choke everything hangin up ,,wrong linkage on lower ..upper hanging up on secondary damper ,,the weight assembly was just wrong ,,so i do get it ...sound effects spot on ,,laughing my ass off every time ... buu buu bb bah buu ..calibration is the key...thanks need more..
I was having a pulsating issue, turned out to be corrosion in the spring hanging up. Hit it with wd and BAM! Full open. Now I have to adjust it because it's too free!
I have one of these 4 barrels on my 1980 Camaro. I can get the car to fire up and run as long as my foot is on the gas. Once off the gas it dies. What do I need to tune on the carb?
I have a Camaro Z28 - 1984 - Trans. manual. T5 Question: When choosing a new and same Quadrajet 4BB carburetor, is it important to know if it is for a trans. auto. or manual??
Can you tell me why mine backfires from the primaries under load then secondaries open and all is good? Timing is 14 initial 34 total. It's a new marine quadrajet.
Hey Tyler, my 83 oldsmobile 98 has that computer controlled qjet. When its warm, it starts up first crank no gas. But if it sits longer than 8 hours or so, it take between 10 and 20 pumps of the gas and alot of cranking before it starts. And even then, its barely enough to fire, I have to be ready to give it a rev so it doesnt stall out right away. I replaced the filter and check valve, made sure the accelerator pump was squirting, and made sure my ISC motor was working. I am stumped. Got any advice for my next course of action?
I have a 1986 Camaro Z28 with a 305 that has a qudrajet i just installed a new one and it has the same issue as my old one after its warmed up i have to kick it down by smashing the gas pedal a couple times then after driving it for a bit when i put oit in park it idles between 12-1500 rpm and is not allowing me to pass emmisions due to the high idle ive checked my vacuum lines all looks good there... What can i do to fix this problem
I bet the electric choke is non-op. What you are doing by punching the gas is activating the "clear-flood" cam that opens the choke at WOT. I would break out the meter and see if the choke is getting power with the key on and the engine RUNNING. GM vehicles of that era usually routed the choke power through the oil pressure switch so that the choke only received power when running. I suspect your problem is in that circuit.
Hey I have a 86 Camaro and the quadrajet doors don’t close on there own, I can open and close them with my finger but it won’t close back up itself, is this normal?
This is the carb on my 87' Monte Carlo. The choke doesn't drop off. It will run 2000rpm. The only way it drops off, is when I am start driving it. Do I have a bad vac? Starts easy, runs fine otherwise.
Hey Tyler. I have what looks to be an original Quadrajet in my daily driver 1979 Cadillac Deville, and it still works flawlessly except for one minor detail. After sitting for a day or two it takes almost five or six seconds to crank it over before it fires up. Is there anything I can do?
I'm no expert on qjets but that doesn't sound like an issue or unusual. Pretty much any carbureted vehicle that you let sit for a few days might take a few more seconds then usual to fire up cause the bowls are most likely empty.
You might have an empty fuel bowl, a weak fuel pump, leaking well plugs in the casting of the carb, a bad accelerator pump, a bad choke or even a vacuum leak or two. The list is extensive I know... but a properly functioning q-jet that isn't compromised by any factors I listed will fire off instantly. Before pulling the carb to see what's going on inside, check your fuel supply, ignition system and vacuum readings. If these are good then it's probably time to crack the carb open and see what's going on inside. If it's never been rebuilt it might be time.
You might take a look at the rubber sections of fuel line that lead from the tank over the axle and between the frame and fuel pump. They can get dried out and cracked enough to permit the line to lose prime but not enough to leak or prevent the engine from running, unless they really crack. Otherwise the ethanol gas tends to evaporate out of the fuel bowl quicker than the old stuff.
I have two GM 350 vehicles. I installed clear gas filters. They always dried out after sitting overnight. So I put a check valve on the fuel line. Now it stays full.
I've watched your videos, I'm impatient af and you keep saying you made a video on it but it's probably labeled as a car name or something. I'm not finding any solutions for my problems 😭 can you just come help me with my carberater pleeeeeease I have a 1989 Chevy motorhome and during renovations it sat with fuel treatment in tank ( stupid) Prior to this, it was a sticky start already. Few pumps, start right up, idle really high and able to kick it down a few times after a few minutes to a nice warm purrrr. Occasionally I would have a rough idle, some days I would idle higher, over idle and do some dieseling. My secondary s were " okay" until they were no more... Currently I have a choke light on, and immediately weezing, kick down not available, and very high heat exhaust. To stop the idle to the moon I turn off the key and a second or two later the exhaust EXPLODES it doesn't sound like a gunshot it sounds like a CANNON help???
1989 Chevy p30 454 quadrajet, 69,000 the carburetor looks mostly original. Electric choke plastic cover broke off and I put a little electric tape over it. I found a few comprised vacuum hoses and replaced them. The kickdown appears to hesitate to to return, after cleaning the linkages etc otherwise in the beginning it seemed like a sticking throddle cable. After freeing up everything else I'm stuck here
I feel like I have to remove the choke and clean the bottom, where it's impossible to get to otherwise. The idle springs, sticking on high idle IDK I'm afraid of creating more problems lol ever near NH??
You found the problem. Your electric choke appears to have broken. It probably dessicated in the underhood heat those things put out. That is why you are getting the "choke" light. The original is riveted in, but you can carefully drill out the rivets and reinstall with screws. Quadrajetparts.com has the replacement choke unit, part # 1211, which includes the screws. The carb likely needs to come off to do this job so i would recommend getting a good kit for it while you are in there. One benefit to the choke replacement is that it makes the choke adjustable...you can loosen the screws and rotate the insert to tune it where it will start easily, etc. As always pay VERY close attention to the condition of the fuel lines, valve cover gaskets and wiring under there..you don't want a fire.
@@TylersNeighborhoodGarage I found the problem, EGR valve was stuck completely, after soaking in cleaner and working a really clean lubricant into it she is purring like a kitten again and now the carburetor is also squeaky clean and lubed LoL, that backfiring was more comparable to key banging my kid said except unintentional of course
Hey Tyler! I have a question for you and it won't take an "extensive answer"😂 If restoring my '86 chevy,and wanting a period correct carb for it,what would be the julian date stamp,"time window",have to note?(3 weeks before the vehicle production date,4 weeks.......)?
The bottom butterflies are connected to the throttle and normally open up, always. There is a spring arrangement that allows the throttle to still open even if the secondary butterflies get stuck closed. The upper secondary air doors only open in reaction to airflow drawn past the sec. butterflies. If the butterflies don't open neither do the air doors.
"Lid flipped Jet" the sound effect at beginning was awesome !! Almost pi seed my pants laughin..thx for vid...But mine has Caps on Air to fuel screw,, vehicle came out of Higher altitude and Running rich...How can I cut them caps out...cut bottom of carb like old style?? Thanks...any help is appreciated. 👍
Thank you. Yes, remove the carb, flip it over and carefully cut a slot just to the outsides of the two caps, then chisel off the caps. You will need the CCC adjusting tools to adjust the screws since they are not regular screw heads. That, or take them out and cut slots in them. If you take them out, run them back in till they LIGHTLY seat, then back out two turns. That will get you started so you can do the final adjustment.
There is a fitting at the top rear of the air horn that looks like a vacuum fitting, but isn't. It is open to filtered air inside the air cleaner. The air is drawn in there, down the tube as it sits in the crossover inside the intake, and back up to the choke. There is a metered vacuum signal on the inside of the choke housing that creates the airflow. Metered means that the carburetor is calibrated to run fine with that vacuum "leak".
The quadrajet was not available until 1965 on the Chevy 396, I don't think anyone rebuilt one in 1962. Rochester did make a 4 barrel that looked similar but it was not a Quadrajet.
Hey Tyler I just watched your video on radiator replacement for Infiniti Q45 1999, awesome thanks, could I communicate briefly with you by email or Facebook etc?
My 69 Buick wildcat turns over but wont start. Battery is good. My first carb carz can someone guide me on what to check and how in some logical order?
Carb or fuel injection, they need three things- air, fuel and spark. Pull a plug wire off a plug, lay in with the end a short distance away from something metal on the engine and crank it over to see if there is spark. If no, pull the distributor cap and file the points. If there is spark, dribble a small amount of fuel down the front venturi of the carb where the choke is and see if it pops off. That will tell you that you aren't getting fuel to the carb. Good luck.
Messing with the vacuum break makes your car bogg at low rpm, sounds good but your hurting your performance. Now, something light with high hp, specifically a manual trans light car with a performance engine yea you can get away with it for more sound, feel, and instant power dump. Can't beat a quad if tuned right and took care of
@@TylersNeighborhoodGarage yes. The front is for the 4 barrel airborne. When at idle you have vacuum which pull the airborne shut. At WOT you start to lose vacuum which allows the airhorn to start to open. I have 4 or 5 carbs here 2 of which are just like tje one in the video and I look to be sure. Both of mine only have a rod that goes to airborne. Now the electric/manual chock carbs do have a lever that keeps the four barrel from opening when chock is active but only the bottom plates not the airhorn.
You know you would be helpful if you completed your thought and explanation! If you plug in vacuum guage you state you dont plug in port manifold! Then what the hell do you plug into?
If you wish to measure manifold vacuum, you determine, via a picture or vacuum diagram, the correct port and attach to it. If you wish to measure ported vacuum, find the correct port and have a blast.
