Recently I purchased a 1989 454 completely stocked and 67 429 completely stock Luckily both have minimal adjustments to all components. Your videos have been absolutely amazingly helpful to me. As a teen in the seventies I know enough to get by but have much more to learn. I appreciate all the knowledge that you have shared and share. I'mma keep wrenching, Thank you
Thank you for the video. I bought a remanufactured carb and the secondary's weren't coming on properly. I watched your video, loosed the spring and drivability is like night and day. Two thumbs up!!
Just got my k20 going today, thanks. Mine was hanging up and I filed it down with my miltitool at the creek, works a lot better. I'm glad I saw that that's ok to do, because I already did it lol
10 years....10 years I dealt with the "WOT bog!" And then I watched your video, walked out to the car, made the adjustments to mimic the spring pressure you showed and BAM, bog gone. In fact, it'll now light the rear tires from a roll just mashing the pedal. Thank you!!
@@91hamod Bog is what happens when you attempt to accelerate your vehicle but instead of gaining rpm, the engine speed slows down, flutters, or completely chokes out. It "bogs" down. Depending on the nature of your engine there can be many different things to take in consideration when trying to correct this problem, but in essence 9 times out of 10 its directly affected by improper fuel/air mixture from the carburetor. You stomp the gas -> improper carburetor tuning -> engine bogs -> complete loss of power and rpm -> a little piece of you dies inside. Carburetors are incrrrrredibly complicated devices with hundreds of completely different designs and applications. Each one must be tuned correctly or else you'll get poor gas mileage, low power, back fire, and eventually bogging as the severity of calibration strays. Hence, the individual above stating it took him 10 years to finally learn what to do to fix his bogging problem from this video. Don't be scared of them though. carburetors are just like any other piece of a vehicle - nuts and bolts. Take some time and watch some videos and eventually you'll slowly understand how simple they can be once you get what makes them tick. If you wish to build a carb for the first time Id suggest starting with a basic Holley. They're very user friendly, simple, and reliable. And because of their natural ON/OFF feeling design, they're great for more aggressive builds if you wish to slowly build you vehicle into something with more performance. I recommend a 4 barrel (4bbl for short) double pumper for a manual transmission and a 4bbl vacuum secondary for an automatic. There's nothing really wrong with a double pumper on an automatic though, just needs a bit more dialing work and throttle control. learn the difference between double pumpers and vacuum secondaries and you'll understand why. Holley actually has a full video series on youtube explaining almost everything you need to know. I hope this clears up a descent sum of you and others questions. Theres always more but I dont have the room to type EVERYTHING here lol. Best of wishes!
Thank you for all of your video's, You have helped me greatly by keeping your explanations in Lamens terms and right to the point without any over explanations. If people are here trying to troll you in any ways i would wonder why they were on your site if they know so much. Thanks again.
VERY HELPFUL VIDEO Thanks for the help this video solved a month long problem i spent alot of time trying to figure out why my truck was booging and had no power when i got into it turns out my airhorn was in fact warped so i replaced it off another quadrajet now everything is great
I have a freshly rebuilt Rochester Quadrajet. When I punch the gas the secondary's barely open. ( I had to dissemble and clean the carb for another reason) but Im certain I re-assembled it correctly. I watched your video and put it back together step by step. Also, when I give the engine a quick punch of gas, there is a slight stall as if its not getting gas right away. Thanks
Great video! My Quadrajet was bogging pretty bad and after following your advice it's running great! Just went and did some victory donuts at full throttle with no bog! :D
Whosaidtyler Thank you for this video. Now I just got to figure out where to get that little return spring because my old one just got bent oyt of shape today.
Top Man Tyler ! My little old 87 Pontiac Firebird 305 has been boggin and surging for almost a year. Trying to find people with knowledge on these here in the UK is like pullin teeth . . . . . painful, every time I thought I found a so called 'expert' they knew less than I did already. I have been 'messin' with the emissions system, and the QJet settings for ages, I tested every solenoid and checked every vacuum line for hold vac, hell I even pulled the EGR valve out and declogged it, and of course adjusted the infamous TV cable, but still my bogging from idle AND during acceleration remained. I have self-learnt and tried what I could 'SEE WITH MY EYES' but all in vain. THEN I found you Qjet video streams and this video led me to that hidden grub-screw used to secure the pre-tension spring for the secondary flaps . . . . . . . torch . . . . . .mirror . . . . .check . . . . . . .found the bugger LOOSE . . . . . . .adjusted the flap tension as you described . . . . . . and took the opportunity to also correctly adjust the choke flap and fast-idle speed. Just took it for run and WOWEE I HAVE MY CAR BACK. After a full year of messin about the problem has turned out to be a small loose grub screw for the secondary flap tension. Keep up the great work Tyler :-)
secondary air door spring adjustments are somewhere between 1/2 and 1 turn by 1/16 of a turn.. 1/2 turn, 9/16 of a turn, 5/8 of a turn, 11/16 of a turn.. all the way to one turn..
I subscribed. Thanks for the info. I'm 16 and working on restoring my 1980 z28 with original 350. Runs great but when you punch it, it hesitates and wants to stall but then picks back up. I'm gonna try this adjustment and if this doesn't help I'm gonna go through and make sure all the screws are adjusted to factory air/fuel mixture
Thank you I have a 1990 454 in my old RV and could not figure out the bog when the secondary should be kicking in going up hills or merging on highway which is so unsafe your video was clear and concise and so much appreciate you take care. I did have one question do you have a picture of the pick up tubes that might have fallen off from another carb or quick advice if easy to see if they have fallen off will try the video first but wanted to verify both just in case thank you again. Rian
Nice video, I understand 50% , I got a problem whit mine, the secondaries above open, but the secondaries plates on the top doesn't, could be the choke? It al seem good, only the top plates doesn't open
doing this to the carb will it fix the cause of gas smeel coming through the mufflers?? i have a 79 z28 n it seems it pass too much gas through.. thank u for your video!
Great video. I rebuilt my quad and it bogs very bad if you step into it at all. I looked and the damper rod for the back four (break) had slipped out. I will put it back and see what happens.
Great video. My secondary's butterfly has no tension in the spring: it stays down if I push it down. even after adjusting the adjustment screw as you show here. The spring you show at 17:46 seems got separated from the rod it is supposed to attach to. Is that spring available as a spare part? I yet have to take the carb off to confirm that the spring has lost that curved end that holds it to the rod. I believe it is broken. Thanks
Great videos and the QJ. I run a QJ in my Ford 460 in a 66 F250. Sorry, not GM or Mopar :) I cannot get the air door to open on the secondaries and so I watched this video with great interest. I tried adjusting the spring as you instruct but that makes no difference. I gather that adjustment is more for closing the door and nor opening it. I also checked all around the opening in the airhorn and there is absolutely nothing rubbing of blocking the door from moving. I took a couple of photos but don't know how to get them to you. My setup is a little different than yours in the video. For one I have only a single vacuum pot on the rear of the carb. It appears to serve the important function you outline here and I can't see that there is a hang up there either. I'm stumped. Any ideas what to try next to get that door moving? I can send photos if there is a way. Thanks, Steve
Nice video, i have a 4 barrel Rochester for my 1988 350 mercruiser. This thing starts right up and runs good until Wide open, then it loses power slowly. I don't think my secondaries are opening. the spring tension is good and my vacuum diaphram has positive suction when i start the engine. But when I hit the gas the vacumm diaphram doesn't release.
Man thank you so much. I finally got my car running right. I got a trans am and a quadrajet is the only thing I can fit under the shaker base. I never could get it to run right and tried everything in the book. Except this. Wow what a difference. I'm sold on the quadrajet now. Great information. Great explanation. I dialed mine in just like your flaps open and close on this video and it's running perfect. No more bog. Not more stumble. Nothing. It's perfect. Thank you for taking the time to do this.
Just sold a carb like that for $20 on marketplace. Late 70s trans am. Now I'm working on the qjet on one of my ol c10s. 1st time I ever put a qjet back in an engine. Usually come off and go on the shelf or give em to a buddy. Figure this time I better learn em.
As soon as I saw the screen on the vent I knew it's a pontiac 800cfm I've been trying to get one for years that is the best rochester ever made my uncle had one on his GTO 400 6X I have watched a few videos of yours. I always hear guys mainly computer tuners say you can't tune part throttle on a carb and I always say NO YOU CAN'T tune a carb at part throttle but i can LOL. now i have a video reference to prove it.
Thanks so much for the video. I have been having this exact problem on my 86 Silverado 305. My Rochester 4B appears to be missing the front damper. Your demo was on a higher performance motor, but am I suppose to have that front damper? Sorry if thats a stupid question. Just want to make sure before I go and try to buy the part.
these are DISPOSABLE. i can't even believe how shitty these carbs are. once they smoke you can look forward to 100+ hours of troubleshooting with 20 'experts' which leads you to buying a new piece of crap carb.
great video man thanks quick question what do i need to adjust when your turn your car on and it smells like gasoline?? i have a 79 z28 with a 350 4 barrel?
Should the secondary doors open if you give it gas when you are in neutral and standing still? How do i know mines are opening? They are closed all the time from what i can see when i stand next to the car and give gas/throttle
Can you do a video on fixing them fucking leaky well plugs? I'm having a shit of a time with my carb leaking down and then it hesitates and I gotta pump the throttle to keep it from dying... NARF!
I've got a 85 k10 and my air doors won't open on the truck if I use my finger all the way like yours did. Is that normal? And it seems like my secondaries won't open all the way with the pedal all the way on the floor. I don't know much about these carbs so please learn me one you get a sec
Looks like u have mopar vehicle fo work bench to work on gm carb? Funny thing is , an old timer told me to bolt a quadra jet on top of my dodge 383 if I ever wanted to get it to run right?
Sorry about not giving all the info but yes anytime I try to accelerate hard it falls flat and doesn't recover unless I let off of the pedal and it's even worse under a load and up hill it won't let me accelerate past 15 mph !
I have problems that the car bog ver very little when I am and in gear and start rolling. Can the secondaries be the problem that they are to loose ? I have no issue at kickdown or other gears.
Is there an easy way to install the spring if it comes out of that slide with that turning screw I just meant mine fell out how do I get back in I'm having a hell of a time
In a all out drag race application, can those two top secondary butterflys be removed? What would be the purpose to have those two large covers in an Wide open throttle drag race vehicle?
Thanks for the info. The previous owner removed the vacuum dampening linkage and all choke linkage, and wiretied the butterfly to an open position. I was considering installing a manual choke, but based on your info it still will not run correctly. Should I try to purchase all the vacuum parts or look a complete rebuilt unit? This carb was put on in place of the original Holley 2barrel.
Well, the linkage pieces are not hard to come by, but they don't come in a rebuild kit. The only things in a rebuild kit are gaskets and rubber bits, plus the inlet needle and seat. What I normally do is look around on eBay to find a core carb that has the stuff I need. You can usually get one pretty cheap if it's really dirty and scummy on the outside. I think that's a pretty common electric-choke, Chevy style carb that was also used on cars and trucks through the mid-eighties. If you can provide your carb number then I can verify what parts carb you should look for. The number is located on the LEFT(side that has the throttle cable) side, on a rib running vertically up and down. It'll be something like 1708816 with 2067 AJC under it. These are just representative numbers, yours will be different.
I have a 67 impala w a 327 engine. My secondary doors don't open unless the car is off. It seems like diaphragm always has vacuum pressure even when I give it gas which doesn't allow the doors open. Any suggestions?
I just bought a q-jet from jet performance a few months ago. Carb runs great just cruising, but when I start getting into the secondaries it start bogging down and kinda spitts. Almost seems like it's starving for fuel. I run it with the air cleaner off, the secondary air doors open slightly. Not sure what is going on with it. Paid $475 for a carb i can even open up
You are losing fuel supply somewhere. The air doors need to be tight enough to stay closed. If the flop open too easily or stay part way open you will never get a clean transition into the secondaries. People get too hung up on "they need to open as wide as they can" mentality. Past that, your symptoms sound suspiciously like some of the secondary pickup tubes have fallen out of the airhorn inside the carb. They press into the bottom of the airhorn and supply the secondary side fuel. There are usually two metering tubes and two pullover enrichment tubes. The pullover tubes supply the small holes at the forward edge of the airdoors with a bit of fuel when the airdoors start to open so it doesn't get a bog before the metering circuit comes in. If your air doors are hanging OPEN then you have effectively disabled that. Rochester spent lots of time making these carbs run very well so I encourage people not to second guess things. I would adjust the spring tension on the airdoors per this video, and then see if your issues resolve. if they do not then you or someone will need to remove the airhorn and have a look at those tubes and the float level. Pick up one of the qjet guide books, it will help immensely.
@Tylers Forgotten Car Rescue (And community) I've got a vaccum secondary, ele choke quadrajet on my nova. It runs fine when it will. But it seems to get stuck wide open. It'll slowly gain rpm, then the secondary flaps start to open, then by then it's climbing so high in rpm you have to shut her down in fear it'll blow up. Soon as you start it again though, it'll idle fine. I'm honestly stumped about this, any help would be appreciated
Do you have any idea of the modifications done to the quadrajet in the 80-81 TA Turbo cars? I'm looking on the net and no one has any info on how to make the "Q" a blow through. Sure I could use a Holley, but I just like being different.
I ran a 81 turbo TA for years when I was a kid - the things Pontiac did to that Quad from the factory was a perfect blend of clockwork and pornography ... anyone who owns one, keep that Quadrajet in good working order but don't modify it, it was perfect the way they designed it with all the factory gear attached
cool video , new to the q-jets , I have a hand full of 4x4 buddy's and they all run the q-jets , mainly because of the center float when 4x4ing , so here is my question . I am missing parts of the q-jet that is related to the choke , I'm on the web . looking and all I can find is like two peace's and cant find the rest with out buying two or three carbs is there a place that I can buy all I need ? I'm running a 7041211 any help would be great , thanks jay
I'm having issues where My secondary doesn't open unless I am flat on the floor. I have to rev well over 4500 rpm to get them open. It doesn't bog, doesn't stumble. Feels like I am running a 2 barrel all the time. Any help? (video's already made)
First thing is to make sure the secondary butterflies are opening when the front barrels reach about halfway open. Often, there is a lockout tab on the choke that prevents the secondaries from opening until the choke opens fully. If your choke isn't unloading fully, that could be an issue, especially considering that the carb is designed to unload the choke by force when the throttle is opened fully (to clear floods). Next, the air doors up top have an adjustment in the spring tension and it's possible someone tightened them too far. I consider that to be least likely. There is usually a pulloff attached to the air doors, but they will still open even if that fails. I am confident you will find your culprit in one of these areas.
I can not get the air doors to shut back on their own. They just flip open and don't shut back and I tried adjusting it. The spring is there but it doesn't seem to do out tension on the doors. It's on a 76 firebird.
Hi great video, i want to buy this carb, i had a holey on it i bought it that way, and now i have a q-jet but it is for a 350 . And my car (a 77 Trans-am 400) really needs this carb :-) so do you want to sell it to me ?
Nicely done videos. I just picked up a 75 Vette and your vids helped me get the carb tuned up. I thought that I might be facing a rebuild, but she's running like a champ after a couple adjustments....sweeeet!
I have that exact same carburetor that im going to be putting on my 73 lemans with a 350 and I have no experience with it. What is the vent tube that went to the bottom of the air cleaner you were talking about? Could I just block it off?
that_gr33n_pontiac Look at the front of the carb and you'll see a large tube that projects vertically. It originally mated with the specific Pontiac air cleaner that had a hole in that area to allow that tube to fit, with a small seal around it, as you can see in the video. You can block it off or take an old foam lawnmower filter and affix it on there securely.
Have you heard that these Rochester's need to have regulated fuel pressure of 3 psi. I have rebuilt my carb cleaned the snot out of it. Nothing in the seat. Float is at the correct height. Searching my head on this thing ran so good last year I wonder if it these new fules.
Thank you for a very instructional video. I have a little problem with my Quadrajet in a 81 Turbo Trans Am. If I hit full throttle fast, the secondary valve opens, engine chokes and stoppes. If I build up RPM more careful, the secondary valve keeps closed and i reach desired max RPM. This mean if I put the hammer down the engine stoppes. Any idea? see video: vimeo.com/161299647
Tyler, Thank you so much for your videos and knowledge sharing on the QJET. This is the third video of yours I have watched and keep learning so much. I need to rebuild the Qjet on my 77 SE TA and your videos are tremendously helpful. Thank you!
hello, okay with you? I have a Thunder 650 and was wondering if you already tried to change the aperture of the secondary air flap .. I wanted to leave it wide open trying to have more hps but I noticed that the engine of the lack of fuel in acceleration will be ... if I increase the jet pump can leave the secondary air flap open?
What is the part called that the secondary metering rod hanger sits on top of? Does it have a pin that secures it? That part was completely loose and a pin is missing it looks like.
I have a summit bought quadrajet #17057553 that I had on my stock pontiac 400. I then rebuilt my motor and added ram air manifolds, ram air 068 cam and 2.5 exhaust. And my current altitude is 5312'. I am not certain what jets I have in there just yet. I guessing stock size, But do you think I should install larger jets and metering rods"? If so, got any idea what size?
Tyler Dude what a life saver. Learning engines my friends Dad (you know the "Cool Dad" Called my quadra jet a quadrajunk and I hated it. Now That I am older and wiser I am rebuilding my baby. a 69 LeMans with a 79 Trans am heart. The Olds 403. Don't judge its what came in it when I bought it. The question is now that you saved it's life by showing me the "hidden Spring" on the secondary air doors. Should I switch to an electronic choke? Or track down and purchase the Hot air original style? If i t's ok to go electronic do you know which one I should use? Thanks again
What about the quadrajet pump ? Have a 1986 GMC sierra classic, and can`t get fuel to the plugs. Any ideas ? Sounds like you can hear fuel in the carburetor when you work the linkage from the pedal, not sure though. #1 SPARK PLUG bone dry !! Fuel is coming to the carburetor from the pump. Don`t no about the pressure though. Pored fuel strait in the throat of the beast still no fuel on plug.
Really appreciate your videos. Just pulled the Quad off my 84 Chevy truck (17084226) and started a rebuild. It was going well until I discovered my air horn is warped. Do you recommend trying to straighten? I did not see that you had any video on correcting warped air horns. I have watched most of your QJ videos over the past week in preparation for the rebuild. Thanks for sharing this information.
Thanks for the video...I just built a 300 HP 305 for my boat.. ported heads, small duration ,small LSA big lift cam..stock low rise but with a 1" 4 hole for velocity and a bunch more goodies...I found I have a bog out of the gate and I'm sure this is it...on Holley's I would just test ,replace with a stiffer spring,test ..most people think it needs to open sooner but it's the opposite so that the carb does not lose all its signal too fast..so simple to adjust..I never knew ,or I did and forgot.. mechanic for over 30 years...great video,thanks for posting..
Hey Tyler, my '77 Corvette with the original QJet has a high idle and I have troubleshot everything I can think of. When it is idling high and I force the secondary air flapper open it drops down a lot. Release it and the idle goes back up. The secondary throttle plates are closed fully. Any idea what is going on here?
Thanks for ur videos they are most helpful. My 73 t/a runs decent until the secondaries kick in then bogs. But if I get the t/a past 60mph and hit it it pulls just fine no bogging. I don't have any vacuum leaks as I can find. The secondaries doors are adjust just like urs. FYI I pro quadrajets.
I have a Rochester 4 BL on a 86 Silverado 305. It only has one Damper on the firewall side. How do I determine if it was suppose to have 2 like the one your going over? These videos have been so helpful. Thanks so much I have learned a lot. After watching this video I thought Praise the Lord I found my problem, only to go out and look and only see 1 damper. I have looked at other pictures of the same carb, so I thought and some have a damper in the front, some in the rear, and some with both. Is there a way to tell which one Im suppose to have?
I just checked timing advance and its on, at least up to 3800rpm. With it running at idle, I can open top secondary doors, which lifts metering rods and fuel should be coming out the small little ports, right? Mine are not, at least at idle and a little above idle. Or does fuel only flow though at high RPM? Just want to check before I tear it apart again.
I realize this is an older video but I wanted to ask you your opinion on this secondary air door/flaps opening and the spring tension you just adjusted. Back around 2000 I rebuilt a 350 Chevy engine out of a '72 Chevy Cheyenne pickup. The machine shop bored the cylinders .030 over, alighn honed it, rebuilt the stock heads, yada yada yada. I installed a mild performance cam, Edlebrock Performer intake and headers with glass packs. I had been researching the book "How to Hotrod The Small Block Chevy" and it had a wealth of information on building street rod engines and talked about how the 4 barrel Quadrajet was a good street rod carb if built and adjusted correctly so that's what I decided to do. The book also talked about how a particular engine could benefit from adjusting those secondary air flaps or doors to either open earlier or later depending on what the engine demanded or wanted. If I remember right it talked about how a built street rod engine would most likely benefit from adjusting them looser than stock to open earlier which is what I did. I never got any on the street experience with this engine because I was only able to break the engine in and run it on the engine stand here and there, I never had a chance to actually get it installed back in the truck because at the time I was doing a frame off restoration and the truck was in many pieces at the time and my fiancee and I split up before I could get it back together. Anyway, I wanted to ask your opinion on this subject if you've had any experience adjusting the secondaries to open sooner than was set at the factory for a hodrod engine and if you think the adjustment makes much of a difference in performance in such a case?
Well, you need to view the adjustment of those air doors as a balancing act, so to speak. They act directly on the secondary metering rods, so anything you do affects the metering. Adjusting them too loose is a common thing that people do and it ends up causing the air doors to pop open so far and so quickly that they bounce back closed, then open again. Guess what happens to the metering rods when they bounce closed? You simply approach the air doors as a tuning operation: drive the vehicle and adjust them until it operates as Rochester intended...no bog, no stumble. Remember that the secondary side is also tuned through the metering rods and the rod hanger. Factory HiPo Qjets also had larger pullover secondary enrichment as well.
@@TylersNeighborhoodGarage Unfortunately I don't have that vehicle anymore or that engine, not for many years but that's good to know for future reference when I build another one. 👍
Thanks for the video! I restored a 1973 Formula 400, 4 barrel, 4 speed, like the new one I had back in the day. Had that Quadrabog problem when I punched it, didn't think the adjustments would really work, but after a few tweaks as described in your videos, the car wants to go sideways with power when the secondary"s open. WOW!
my dad had one on a 85 caprice 2 door 305 quadrajet. ran great for years no problem. I just recently purchased a 83 c10 with the 305. having some issues but I am learning how to work on it .
Thank you. My Chevelle Quadrajet must have it too tight. The secondaries only open just a little. Even at full throttle. Your videos are very helpful. Mine had the choke rigged to always be open.
Great videos! I was able to rebuild my quadrajet using them. The car is running great except for one small problem; the secondary needle hangar cam is missing. I bought a new one but how do I put it in? Is there a way to put it on without taking apart the secondary air valve? which way does it go? I don't want to install it backwards.
What does turning the screw that your finger is on @ 4:00? It's connected to the Choke, but doesn't seem to actually limit anything? I looked in my Cliff Ruggles Qjet book and couldn't find anything to tell me what it does...
i rebuilt ( with a good chem. soak too ) a e34mc, and did everything, including the choke plate adjust with choke level gauge, the one with the bubble, and it works great. yes, i had to adjust that spring, and file the lock out pin for the butter fly's on the secondary. i loved it. set up a bench with leveler plate and all. the tools were a bit hard to obtain, and i made some of them, but i did every single thing that could possibly be done. all of it. the fucker rips ass now! edit: sometimes the hanging up you mentioned on the secondary , comes from that spring you just adjusted, it starts with a little snag on the initial movement. oil it up good and a hair, i mean a hair looser on the adjust is all you need. my choke pull off went out, and i took mine off and had to wire the fast idle cam down, so the secondary lock out pin would not interfere with the operation of my secondary. hell, wire that secondary top plate wide open too and give it gas. hahaha. fuck rochester!
You know a lot about carbs and was wondering if I could get your advice I have a 84 Camaro with a 305 that has a quad on it and I can't get the scandals to open and I don't know why my carb dose everything that yours dose and it's in really good condition. I just don't know why
Can you tell me why some quads with the electric choke don't have the secondary brake on the rear of it. I believe that is what it is called. The one in this video has on attached to it but some don't. Is it necessary to have it? Also what do you think about the Edelbrock Quads that were made? Are they as good or better than regular quadrajets? Thanks
i reacently tried to make this adjustmeant after having this bog issue step by step i done as you showed with your finger testing its tention after my adjustmeant and it made a snap noise now the sring doesnt pull the flaps closed??! I didnt turn it that tight im sure so im hopeing the spring would by chance just have came loose i even tried putting the tension back loose and its still the same. Do you have any opion on how i can check to se why the sring doesnt work or if its fixable without taking it off my engine?
Recently I purchased a 1989 454 completely stocked and 67 429 completely stock
Luckily both have minimal adjustments to all components.
Your videos have been absolutely amazingly helpful to me. As a teen in the seventies I know enough to get by but have much more to learn. I appreciate all the knowledge that you have shared and share.
I'mma keep wrenching,
Thank you
Thank you for the video. I bought a remanufactured carb and the secondary's weren't coming on properly. I watched your video, loosed the spring and drivability is like night and day. Two thumbs up!!
sweet!
Just got my k20 going today, thanks. Mine was hanging up and I filed it down with my miltitool at the creek, works a lot better. I'm glad I saw that that's ok to do, because I already did it lol
10 years....10 years I dealt with the "WOT bog!" And then I watched your video, walked out to the car, made the adjustments to mimic the spring pressure you showed and BAM, bog gone. In fact, it'll now light the rear tires from a roll just mashing the pedal. Thank you!!
Glad to help!
What is bog?
@@91hamod Bog is what happens when you attempt to accelerate your vehicle but instead of gaining rpm, the engine speed slows down, flutters, or completely chokes out. It "bogs" down.
Depending on the nature of your engine there can be many different things to take in consideration when trying to correct this problem, but in essence 9 times out of 10 its directly affected by improper fuel/air mixture from the carburetor. You stomp the gas -> improper carburetor tuning -> engine bogs -> complete loss of power and rpm -> a little piece of you dies inside.
Carburetors are incrrrrredibly complicated devices with hundreds of completely different designs and applications. Each one must be tuned correctly or else you'll get poor gas mileage, low power, back fire, and eventually bogging as the severity of calibration strays. Hence, the individual above stating it took him 10 years to finally learn what to do to fix his bogging problem from this video.
Don't be scared of them though. carburetors are just like any other piece of a vehicle - nuts and bolts. Take some time and watch some videos and eventually you'll slowly understand how simple they can be once you get what makes them tick. If you wish to build a carb for the first time Id suggest starting with a basic Holley. They're very user friendly, simple, and reliable. And because of their natural ON/OFF feeling design, they're great for more aggressive builds if you wish to slowly build you vehicle into something with more performance.
I recommend a 4 barrel (4bbl for short) double pumper for a manual transmission and a 4bbl vacuum secondary for an automatic. There's nothing really wrong with a double pumper on an automatic though, just needs a bit more dialing work and throttle control. learn the difference between double pumpers and vacuum secondaries and you'll understand why. Holley actually has a full video series on youtube explaining almost everything you need to know.
I hope this clears up a descent sum of you and others questions. Theres always more but I dont have the room to type EVERYTHING here lol. Best of wishes!
Figured out my backfiring issue, it was timing, the quadrajet is singing now! Thanks again.
Thank you for all of your video's, You have helped me greatly by keeping your explanations in Lamens terms and right to the point without any over explanations. If people are here trying to troll you in any ways i would wonder why they were on your site if they know so much. Thanks again.
VERY HELPFUL VIDEO Thanks for the help this video solved a month long problem i spent alot of time trying to figure out why my truck was booging and had no power when i got into it turns out my airhorn was in fact warped so i replaced it off another quadrajet now everything is great
Rambling on and on! How about a vid that’s just on adjusting the carb. I’m having a hard time watching a 17:00 vid for a 5 second adjustment
I have a freshly rebuilt Rochester Quadrajet. When I punch the gas the secondary's barely open. ( I had to dissemble and clean the carb for another reason) but Im certain I re-assembled it correctly. I watched your video and put it back together step by step. Also, when I give the engine a quick punch of gas, there is a slight stall as if its not getting gas right away. Thanks
It was a big help thanks try it tomorrow have a great holiday 😀
Great video! My Quadrajet was bogging pretty bad and after following your advice it's running great! Just went and did some victory donuts at full throttle with no bog! :D
Best video ever for a description of the secondary flaps, their adjustment and the pull of dampener. Thanks 🙏
Great videos
Nothing like hearing those secondaries suck down some air and fuel
A++ Got 90% of the bogg out of my Qjet! Still have some fine tuning but nice to fix an issue with a few tools instead of a few parts.
Whosaidtyler Thank you for this video. Now I just got to figure out where to get that little return spring because my old one just got bent oyt of shape today.
I miss think I broke my spring and then when I was taking the screw out I lost a screw is anywhere I can get a new screw and spring
Top Man Tyler ! My little old 87 Pontiac Firebird 305 has been boggin and surging for almost a year. Trying to find people with knowledge on these here in the UK is like pullin teeth . . . . . painful, every time I thought I found a so called 'expert' they knew less than I did already. I have been 'messin' with the emissions system, and the QJet settings for ages, I tested every solenoid and checked every vacuum line for hold vac, hell I even pulled the EGR valve out and declogged it, and of course adjusted the infamous TV cable, but still my bogging from idle AND during acceleration remained. I have self-learnt and tried what I could 'SEE WITH MY EYES' but all in vain. THEN I found you Qjet video streams and this video led me to that hidden grub-screw used to secure the pre-tension spring for the secondary flaps . . . . . . . torch . . . . . .mirror . . . . .check . . . . . . .found the bugger LOOSE . . . . . . .adjusted the flap tension as you described . . . . . . and took the opportunity to also correctly adjust the choke flap and fast-idle speed. Just took it for run and WOWEE I HAVE MY CAR BACK. After a full year of messin about the problem has turned out to be a small loose grub screw for the secondary flap tension. Keep up the great work Tyler :-)
secondary air door spring adjustments are somewhere between 1/2 and 1 turn by 1/16 of a turn.. 1/2 turn, 9/16 of a turn, 5/8 of a turn, 11/16 of a turn.. all the way to one turn..
I subscribed. Thanks for the info. I'm 16 and working on restoring my 1980 z28 with original 350. Runs great but when you punch it, it hesitates and wants to stall but then picks back up. I'm gonna try this adjustment and if this doesn't help I'm gonna go through and make sure all the screws are adjusted to factory air/fuel mixture
Thanks video real helpful and keep original carburetor 💯
Thank you I have a 1990 454 in my old RV and could not figure out the bog when the secondary should be kicking in going up hills or merging on highway which is so unsafe your video was clear and concise and so much appreciate you take care. I did have one question do you have a picture of the pick up tubes that might have fallen off from another carb or quick advice if easy to see if they have fallen off will try the video first but wanted to verify both just in case thank you again. Rian
There are many great Book's on Q jets that have all the information you will ever need.
Nice video, I understand 50% , I got a problem whit mine, the secondaries above open, but the secondaries plates on the top doesn't, could be the choke? It al seem good, only the top plates doesn't open
doing this to the carb will it fix the cause of gas smeel coming through the mufflers?? i have a 79 z28 n it seems it pass too much gas through.. thank u for your video!
Great video. I rebuilt my quad and it bogs very bad if you step into it at all. I looked and the damper rod for the back four (break) had slipped out. I will put it back and see what happens.
Great video. My 85 C10 5.7ltr and I thank you. :)
You are welcome.
What if that dampner has constant vacuum even with the engine at higher rpm and it is keeping the secondaries pulled shut all the time? Thanks
Great video. My secondary's butterfly has no tension in the spring: it stays down if I push it down. even after adjusting the adjustment screw as you show here. The spring you show at 17:46 seems got separated from the rod it is supposed to attach to. Is that spring available as a spare part? I yet have to take the carb off to confirm that the spring has lost that curved end that holds it to the rod. I believe it is broken.
Thanks
There's a place called Quadrajet-parts on the internet that may have it. Otherwise, you might buy a cheap parts carb off ebay to get the part.
Great videos and the QJ. I run a QJ in my Ford 460 in a 66 F250. Sorry, not GM or Mopar :) I cannot get the air door to open on the secondaries and so I watched this video with great interest. I tried adjusting the spring as you instruct but that makes no difference. I gather that adjustment is more for closing the door and nor opening it. I also checked all around the opening in the airhorn and there is absolutely nothing rubbing of blocking the door from moving. I took a couple of photos but don't know how to get them to you. My setup is a little different than yours in the video. For one I have only a single vacuum pot on the rear of the carb. It appears to serve the important function you outline here and I can't see that there is a hang up there either. I'm stumped. Any ideas what to try next to get that door moving? I can send photos if there is a way. Thanks, Steve
Nice video, i have a 4 barrel Rochester for my 1988 350 mercruiser. This thing starts right up and runs good until Wide open, then it loses power slowly. I don't think my secondaries are opening. the spring tension is good and my vacuum diaphram has positive suction when i start the engine. But when I hit the gas the vacumm diaphram doesn't release.
Thank you for posting these. I learned SO much from you, and now I don't run anything except quadrajets. THANKS!
I'm glad.
Man thank you so much. I finally got my car running right. I got a trans am and a quadrajet is the only thing I can fit under the shaker base. I never could get it to run right and tried everything in the book. Except this. Wow what a difference. I'm sold on the quadrajet now. Great information. Great explanation. I dialed mine in just like your flaps open and close on this video and it's running perfect. No more bog. Not more stumble. Nothing. It's perfect. Thank you for taking the time to do this.
Dude thank you so much!!
Just sold a carb like that for $20 on marketplace. Late 70s trans am. Now I'm working on the qjet on one of my ol c10s. 1st time I ever put a qjet back in an engine. Usually come off and go on the shelf or give em to a buddy. Figure this time I better learn em.
As soon as I saw the screen on the vent I knew it's a pontiac 800cfm I've been trying to get one for years that is the best rochester ever made my uncle had one on his GTO 400 6X I have watched a few videos of yours. I always hear guys mainly computer tuners say you can't tune part throttle on a carb and I always say NO YOU CAN'T tune a carb at part throttle but i can LOL. now i have a video reference to prove it.
Thanks so much for the video. I have been having this exact problem on my 86 Silverado 305. My Rochester 4B appears to be missing the front damper. Your demo was on a higher performance motor, but am I suppose to have that front damper? Sorry if thats a stupid question. Just want to make sure before I go and try to buy the part.
these are DISPOSABLE. i can't even believe how shitty these carbs are. once they smoke you can look forward to 100+ hours of troubleshooting with 20 'experts' which leads you to buying a new piece of crap carb.
great video man thanks quick question what do i need to adjust when your turn your car on and it smells like gasoline?? i have a 79 z28 with a 350 4 barrel?
Should the secondary doors open if you give it gas when you are in neutral and standing still? How do i know mines are opening? They are closed all the time from what i can see when i stand next to the car and give gas/throttle
Can you do a video on fixing them fucking leaky well plugs? I'm having a shit of a time with my carb leaking down and then it hesitates and I gotta pump the throttle to keep it from dying... NARF!
The spring is not tightening the secondary doors.
Help!
EDIT 👇🏻👇🏻
I figured out that the spring is worn out. Is it simple to replace??
Thanks for the video. Just bought a C30 and the secondary flaps had no spring tension. It would open up if you looked at it the wrong way. 😂
I've got a 85 k10 and my air doors won't open on the truck if I use my finger all the way like yours did. Is that normal? And it seems like my secondaries won't open all the way with the pedal all the way on the floor. I don't know much about these carbs so please learn me one you get a sec
Looks like u have mopar vehicle fo work bench to work on gm carb? Funny thing is , an old timer told me to bolt a quadra jet on top of my dodge 383 if I ever wanted to get it to run right?
Sorry about not giving all the info but yes anytime I try to accelerate hard it falls flat and doesn't recover unless I let off of the pedal and it's even worse under a load and up hill it won't let me accelerate past 15 mph !
I have problems that the car bog ver very little when I am and in gear and start rolling. Can the secondaries be the problem that they are to loose ? I have no issue at kickdown or other gears.
Is there an easy way to install the spring if it comes out of that slide with that turning screw I just meant mine fell out how do I get back in I'm having a hell of a time
In a all out drag race application, can those two top secondary butterflys be removed? What would be the purpose to have those two large covers in an Wide open throttle drag race vehicle?
The spring was fine in mine but the cam that pushes up the needles was broken and got stuck in there and the flaps wouldn't open.
Thanks for the info. The previous owner removed the vacuum dampening linkage and all choke linkage, and wiretied the butterfly to an open position. I was considering installing a manual choke, but based on your info it still will not run correctly. Should I try to purchase all the vacuum parts or look a complete rebuilt unit? This carb was put on in place of the original Holley 2barrel.
Well, the linkage pieces are not hard to come by, but they don't come in a rebuild kit. The only things in a rebuild kit are gaskets and rubber bits, plus the inlet needle and seat.
What I normally do is look around on eBay to find a core carb that has the stuff I need. You can usually get one pretty cheap if it's really dirty and scummy on the outside.
I think that's a pretty common electric-choke, Chevy style carb that was also used on cars and trucks through the mid-eighties. If you can provide your carb number then I can verify what parts carb you should look for. The number is located on the LEFT(side that has the throttle cable) side, on a rib running vertically up and down.
It'll be something like 1708816 with 2067 AJC under it. These are just representative numbers, yours will be different.
I have a 67 impala w a 327 engine. My secondary doors don't open unless the car is off. It seems like diaphragm always has vacuum pressure even when I give it gas which doesn't allow the doors open. Any suggestions?
10:30 start of how to adjust it
You know if GM did away with 2 Chorcoal Canisters on dual tank C10s and 20s?
I just bought a q-jet from jet performance a few months ago. Carb runs great just cruising, but when I start getting into the secondaries it start bogging down and kinda spitts. Almost seems like it's starving for fuel. I run it with the air cleaner off, the secondary air doors open slightly. Not sure what is going on with it. Paid $475 for a carb i can even open up
You are losing fuel supply somewhere. The air doors need to be tight enough to stay closed. If the flop open too easily or stay part way open you will never get a clean transition into the secondaries. People get too hung up on "they need to open as wide as they can" mentality. Past that, your symptoms sound suspiciously like some of the secondary pickup tubes have fallen out of the airhorn inside the carb. They press into the bottom of the airhorn and supply the secondary side fuel. There are usually two metering tubes and two pullover enrichment tubes. The pullover tubes supply the small holes at the forward edge of the airdoors with a bit of fuel when the airdoors start to open so it doesn't get a bog before the metering circuit comes in. If your air doors are hanging OPEN then you have effectively disabled that. Rochester spent lots of time making these carbs run very well so I encourage people not to second guess things. I would adjust the spring tension on the airdoors per this video, and then see if your issues resolve. if they do not then you or someone will need to remove the airhorn and have a look at those tubes and the float level. Pick up one of the qjet guide books, it will help immensely.
@Tylers Forgotten Car Rescue
(And community)
I've got a vaccum secondary, ele choke quadrajet on my nova. It runs fine when it will. But it seems to get stuck wide open. It'll slowly gain rpm, then the secondary flaps start to open, then by then it's climbing so high in rpm you have to shut her down in fear it'll blow up.
Soon as you start it again though, it'll idle fine.
I'm honestly stumped about this, any help would be appreciated
Also to add, it all functions very smoothly. Nothing is hanging up. It just gets stuck wide open.
Does bog mean too much air in the mixture, coming from the vents?
Yes, it tries to momentarily ingest more air than it can use.
Do you have any idea of the modifications done to the quadrajet in the 80-81 TA Turbo cars? I'm looking on the net and no one has any info on how to make the "Q" a blow through. Sure I could use a Holley, but I just like being different.
I ran a 81 turbo TA for years when I was a kid - the things Pontiac did to that Quad from the factory was a perfect blend of clockwork and pornography ... anyone who owns one, keep that Quadrajet in good working order but don't modify it, it was perfect the way they designed it with all the factory gear attached
adjusting secondary, will it help spuddering at at higher rpm as well?
Have you ever had low octane gas make your engine knock I had ran out of gas and put cheap gas in and now I have a knock in my motor
cool video , new to the q-jets , I have a hand full of 4x4 buddy's and they all run the q-jets , mainly because of the center float when 4x4ing , so here is my question . I am missing parts of the q-jet that is related to the choke , I'm on the web . looking and all I can find is like two peace's and cant find the rest with out buying two or three carbs is there a place that I can buy all I need ? I'm running a 7041211 any help would be great , thanks jay
Try quadrajetparts.com. Good luck!
My rear vacuum break won’t open up to let the secondaries open, even after the cars warmed up and choke is off
Do you know how to work on a non automatic carburetor. Would help a lot!!!!!
I'm having issues where My secondary doesn't open unless I am flat on the floor. I have to rev well over 4500 rpm to get them open. It doesn't bog, doesn't stumble. Feels like I am running a 2 barrel all the time. Any help? (video's already made)
First thing is to make sure the secondary butterflies are opening when the front barrels reach about halfway open. Often, there is a lockout tab on the choke that prevents the secondaries from opening until the choke opens fully. If your choke isn't unloading fully, that could be an issue, especially considering that the carb is designed to unload the choke by force when the throttle is opened fully (to clear floods). Next, the air doors up top have an adjustment in the spring tension and it's possible someone tightened them too far. I consider that to be least likely. There is usually a pulloff attached to the air doors, but they will still open even if that fails. I am confident you will find your culprit in one of these areas.
What size allen key? Just wondering. Thanks!
cranking down on the air cleaner nut warps the air horns too causing them to hang up.
can you do a video show how the secondary door spring is installed. I turned my set screw to find out the spring is not attached.
thank you
Yeh I snapped mine
I can not get the air doors to shut back on their own. They just flip open and don't shut back and I tried adjusting it. The spring is there but it doesn't seem to do out tension on the doors. It's on a 76 firebird.
That's a rare issue. Let me dig one out and look at it...I'll get back to you.
The spring might be broken. I'll pull the carb off and see if I can get a better look.
Hi great video, i want to buy this carb, i had a holey on it i bought it that way, and now i have a q-jet but it is for a 350 .
And my car (a 77 Trans-am 400) really needs this carb :-) so do you want to sell it to me ?
I'm afraid I can't but I have good luck using ebay to find carbs. Use the correct carb number and start searching..good luck!
Nicely done videos. I just picked up a 75 Vette and your vids helped me get the carb tuned up. I thought that I might be facing a rebuild, but she's running like a champ after a couple adjustments....sweeeet!
The Quadrajet is the most reliable carb For GM
if it bogs is it because the spring is tight or too loose which way do you want to go?
I have that exact same carburetor that im going to be putting on my 73 lemans with a 350 and I have no experience with it. What is the vent tube that went to the bottom of the air cleaner you were talking about? Could I just block it off?
that_gr33n_pontiac Look at the front of the carb and you'll see a large tube that projects vertically. It originally mated with the specific Pontiac air cleaner that had a hole in that area to allow that tube to fit, with a small seal around it, as you can see in the video.
You can block it off or take an old foam lawnmower filter and affix it on there securely.
and im glad you have a lot of qudrajet videos
Have you heard that these Rochester's need to have regulated fuel pressure of 3 psi.
I have rebuilt my carb cleaned the snot out of it.
Nothing in the seat. Float is at the correct height.
Searching my head on this thing ran so good last year I wonder if it these new fules.
haven't heard that.
Thank you for a very instructional video. I have a little problem with
my Quadrajet in a 81 Turbo Trans Am. If I hit full throttle fast, the
secondary valve opens, engine chokes and stoppes. If I build up RPM more
careful, the secondary valve keeps closed and i reach desired max RPM.
This mean if I put the hammer down the engine stoppes. Any idea? see
video: vimeo.com/161299647
Tyler, Thank you so much for your videos and knowledge sharing on the QJET. This is the third video of yours I have watched and keep learning so much. I need to rebuild the Qjet on my 77 SE TA and your videos are tremendously helpful. Thank you!
Thank you brother! It helped me figure out the issue on my 85 C-10 305. I appreciate your help!
Sweet
hello, okay with you? I have a Thunder 650 and was wondering if you already tried to change the aperture of the secondary air flap .. I wanted to leave it wide open trying to have more hps but I noticed that the engine of the lack of fuel in acceleration will be ... if I increase the jet pump can leave the secondary air flap open?
What is the part called that the secondary metering rod hanger sits on top of? Does it have a pin that secures it? That part was completely loose and a pin is missing it looks like.
There is a plastic cam mounted on the air door shaft, then a retainer, then the rod hanger is fastened to that with a small screw.
I have a summit bought quadrajet #17057553 that I had on my stock pontiac 400. I then rebuilt my motor and added ram air manifolds, ram air 068 cam and 2.5 exhaust. And my current altitude is 5312'. I am not certain what jets I have in there just yet. I guessing stock size, But do you think I should install larger jets and metering rods"? If so, got any idea what size?
Tyler Dude what a life saver. Learning engines my friends Dad (you know the "Cool Dad" Called my quadra jet a quadrajunk and I hated it. Now That I am older and wiser I am rebuilding my baby. a 69 LeMans with a 79 Trans am heart. The Olds 403. Don't judge its what came in it when I bought it. The question is now that you saved it's life by showing me the "hidden Spring" on the secondary air doors. Should I switch to an electronic choke? Or track down and purchase the Hot air original style? If i t's ok to go electronic do you know which one I should use? Thanks again
What about the quadrajet pump ? Have a 1986 GMC sierra classic, and can`t get fuel to the plugs. Any ideas ? Sounds like you can hear fuel in the carburetor when you work the linkage from the pedal, not sure though. #1 SPARK PLUG bone dry !! Fuel is coming to the carburetor from the pump. Don`t no about the pressure though. Pored fuel strait in the throat of the beast still no fuel on plug.
Really appreciate your videos. Just pulled the Quad off my 84 Chevy truck (17084226) and started a rebuild. It was going well until I discovered my air horn is warped. Do you recommend trying to straighten? I did not see that you had any video on correcting warped air horns. I have watched most of your QJ videos over the past week in preparation for the rebuild. Thanks for sharing this information.
Thanks for the video...I just built a 300 HP 305 for my boat.. ported heads, small duration ,small LSA big lift cam..stock low rise but with a 1" 4 hole for velocity and a bunch more goodies...I found I have a bog out of the gate and I'm sure this is it...on Holley's I would just test ,replace with a stiffer spring,test ..most people think it needs to open sooner but it's the opposite so that the carb does not lose all its signal too fast..so simple to adjust..I never knew ,or I did and forgot.. mechanic for over 30 years...great video,thanks for posting..
Hey Tyler, my '77 Corvette with the original QJet has a high idle and I have troubleshot everything I can think of. When it is idling high and I force the secondary air flapper open it drops down a lot. Release it and the idle goes back up. The secondary throttle plates are closed fully. Any idea what is going on here?
Thanks for ur videos they are most helpful. My 73 t/a runs decent until the secondaries kick in then bogs. But if I get the t/a past 60mph and hit it it pulls just fine no bogging. I don't have any vacuum leaks as I can find. The secondaries doors are adjust just like urs. FYI I pro quadrajets.
I have a Rochester 4 BL on a 86 Silverado 305. It only has one Damper on the firewall side. How do I determine if it was suppose to have 2 like the one your going over? These videos have been so helpful. Thanks so much I have learned a lot. After watching this video I thought Praise the Lord I found my problem, only to go out and look and only see 1 damper. I have looked at other pictures of the same carb, so I thought and some have a damper in the front, some in the rear, and some with both. Is there a way to tell which one Im suppose to have?
I just checked timing advance and its on, at least up to 3800rpm. With it running at idle, I can open top secondary doors, which lifts metering rods and fuel should be coming out the small little ports, right? Mine are not, at least at idle and a little above idle. Or does fuel only flow though at high RPM? Just want to check before I tear it apart again.
Thank you for your knowledge and help!
I realize this is an older video but I wanted to ask you your opinion on this secondary air door/flaps opening and the spring tension you just adjusted. Back around 2000 I rebuilt a 350 Chevy engine out of a '72 Chevy Cheyenne pickup. The machine shop bored the cylinders .030 over, alighn honed it, rebuilt the stock heads, yada yada yada. I installed a mild performance cam, Edlebrock Performer intake and headers with glass packs. I had been researching the book "How to Hotrod The Small Block Chevy" and it had a wealth of information on building street rod engines and talked about how the 4 barrel Quadrajet was a good street rod carb if built and adjusted correctly so that's what I decided to do. The book also talked about how a particular engine could benefit from adjusting those secondary air flaps or doors to either open earlier or later depending on what the engine demanded or wanted. If I remember right it talked about how a built street rod engine would most likely benefit from adjusting them looser than stock to open earlier which is what I did. I never got any on the street experience with this engine because I was only able to break the engine in and run it on the engine stand here and there, I never had a chance to actually get it installed back in the truck because at the time I was doing a frame off restoration and the truck was in many pieces at the time and my fiancee and I split up before I could get it back together. Anyway, I wanted to ask your opinion on this subject if you've had any experience adjusting the secondaries to open sooner than was set at the factory for a hodrod engine and if you think the adjustment makes much of a difference in performance in such a case?
Well, you need to view the adjustment of those air doors as a balancing act, so to speak. They act directly on the secondary metering rods, so anything you do affects the metering. Adjusting them too loose is a common thing that people do and it ends up causing the air doors to pop open so far and so quickly that they bounce back closed, then open again. Guess what happens to the metering rods when they bounce closed? You simply approach the air doors as a tuning operation: drive the vehicle and adjust them until it operates as Rochester intended...no bog, no stumble. Remember that the secondary side is also tuned through the metering rods and the rod hanger. Factory HiPo Qjets also had larger pullover secondary enrichment as well.
@@TylersNeighborhoodGarage Unfortunately I don't have that vehicle anymore or that engine, not for many years but that's good to know for future reference when I build another one. 👍
Thanks for the video! I restored a 1973 Formula 400, 4 barrel, 4 speed, like the new one I had back in the day. Had that Quadrabog problem when I punched it, didn't think the adjustments would really work, but after a few tweaks as described in your videos, the car wants to go sideways with power when the secondary"s open. WOW!
Can I run the line for the front vacuum brake straight to manifold pressure?
yes
Like your videos. Curious What is the adjustment screw that sits on top of the choke housing?
That's probably the adjustment for the vacuum pulloff distance. It has to do with the amount that it "pulls off" the choke plate on a cold start.
my dad had one on a 85 caprice 2 door 305 quadrajet. ran great for years no problem. I just recently purchased a 83 c10 with the 305. having some issues but I am learning how to work on it .
Thank you. My Chevelle Quadrajet must have it too tight. The secondaries only open just a little. Even at full throttle. Your videos are very helpful. Mine had the choke rigged to always be open.
Great videos! I was able to rebuild my quadrajet using them. The car is running great except for one small problem; the secondary needle hangar cam is missing. I bought a new one but how do I put it in? Is there a way to put it on without taking apart the secondary air valve? which way does it go? I don't want to install it backwards.
What does turning the screw that your finger is on @ 4:00? It's connected to the Choke, but doesn't seem to actually limit anything? I looked in my Cliff Ruggles Qjet book and couldn't find anything to tell me what it does...
i rebuilt ( with a good chem. soak too ) a e34mc, and did everything, including the choke plate adjust with choke level gauge, the one with the bubble, and it works great. yes, i had to adjust that spring, and file the lock out pin for the butter fly's on the secondary. i loved it. set up a bench with leveler plate and all. the tools were a bit hard to obtain, and i made some of them, but i did every single thing that could possibly be done. all of it. the fucker rips ass now! edit: sometimes the hanging up you mentioned on the secondary , comes from that spring you just adjusted, it starts with a little snag on the initial movement. oil it up good and a hair, i mean a hair looser on the adjust is all you need. my choke pull off went out, and i took mine off and had to wire the fast idle cam down, so the secondary lock out pin would not interfere with the operation of my secondary. hell, wire that secondary top plate wide open too and give it gas. hahaha. fuck rochester!
You know a lot about carbs and was wondering if I could get your advice I have a 84 Camaro with a 305 that has a quad on it and I can't get the scandals to open and I don't know why my carb dose everything that yours dose and it's in really good condition. I just don't know why
Can you tell me why some quads with the electric choke don't have the secondary brake on the rear of it. I believe that is what it is called. The one in this video has on attached to it but some don't. Is it necessary to have it?
Also what do you think about the Edelbrock Quads that were made? Are they as good or better than regular quadrajets?
Thanks
i reacently tried to make this adjustmeant after having this bog issue step by step i done as you showed with your finger testing its tention after my adjustmeant and it made a snap noise now the sring doesnt pull the flaps closed??! I didnt turn it that tight im sure so im hopeing the spring would by chance just have came loose i even tried putting the tension back loose and its still the same. Do you have any opion on how i can check to se why the sring doesnt work or if its fixable without taking it off my engine?