04. My Tom Mobley prepared Quadrajet in action. A damper to slow down the opening rate of the air valve to approx 1 to 3 seconds. They were touching the bottom of the air cleaner, and apparently they were only arcing under acceleration under load. The Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800 cfm. By comparison, a "square bore" carburetor has primary and secondary venturis of similar size. Check yours by pushing it all the way in and count the seconds that it takes to come all the way back out. Timed to ~6 BTDC with vacuum advance disconnected.HEI distributor Elevation is 9,000ft. Convenient when it's time to pin the butterflies. Float level may be too low set to specifications. Kits, Seadog Stainless Steel Cup If your car or truck is equipped with a Holley four barrel carburetor and stumbles upon acceleration, more than likely the carburetor needs an adjustment to the accelerator pump assembly. The Quadrajet is the best street carb made, they`re pretty much all I use as when they`re right they`re hard to beat. Another important issue with Quadrajets is carburetor sizing. All, Anchor & Because the Quadrajet is a vacuum controlled spreadbore carburetor, it can be tricky to tune. By comparison, a "square bore" carburetor has primary and secondary venturis of similar size. For a better experience, please enable JavaScript in your browser before proceeding. Timed to ~6 BTDC with vacuum advance disconnected.HEI distributor Elevation is 9,000ft. Boats, Propeller Parts & The downside to older Quadrajet cores is abuse and core shift. The rod connects to the choke unloader which serves as: 1. Furniture, Boat Seat Pedestals & This is the release rate. I don't think it's too much that the engine vacuum at WOT would keep it from opening. Most modern This is known as electronic mixture control. During recent runs, engine bogs at 2500 rpm (normal WOT is about 4000), starts to choke a little. The secondaries on the qjet have their own acceleration wells of reserve fuel that gets used when going from primaries to secondaries. Blocks, Marine the pin in the throttle rod for the secondaries might not be keeping the secondaries closed. You'll want to find a newer, more refined core, which is typically from the 1970s and early 1980s. Like bypass it? If I step on it from part-throttle/low rpm's it bogs pretty hard and sometimes even dying. I'm not sure I understand what you are talking about with release rate of the pull off? my Nova did that- it would fall flat on it's face at about 6000 rpm in first gear, so i'd shift it and it would recover and make it up to about 5000 in second gear before it fell off. Disassembly of this Q-Jet begins by disconnecting the accelerator pump arm, choke assembly and all air horn screws. merry christmas RLS. Kits, Boat Trailer Not having the secondary air valve linkage rod in place can cause a bog when the air valve snaps open under heavy throttle. All, Boat Bimini See if all is same then? Telescopes, Covers and Could this work just as well in place of the choke rod? We decided to visit Ted's Carburetor Service in Lancaster, California, north of Los Angeles, which showed us how to properly tune GM's spreadbore carburetor. 2. The Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800 cfm. Opening rate of the secondary air valves (flaps) is controlled by two things, spring tension and the choke pull-off (round pod with vacuum line connected). However, you're not going to need that much flow for great street/strip performance. Screws, Boat Handles, Pulls, The new fuel pump just may not be up to the job anymore. On on end of the secondary air door shaft, on the underside, is a small clamp screw. Holder, Anchor & Dock where is the fuel filter and how old is it? Grills, Boat Drink However, when you start making modifications such a hot roller camshaft, aftermarket induction and heads, and a host of other performance elements the Quadrajet struggles to keep up. Breakers, Power Packs & Jump A spread-bore by design, the Quadrajet is particularly effective in street form, with small primaries that offer exceptional throttle response, yet good fuel economy, while its large air valve-controlled secondaries have the ability to deliver maximum, seat-of-the-pants performance in an instant. With core shift comes altered and closed off passages. I fixed the needle retaining clip and was playing around with the accelerator pump and noticed I'm only getting one stream of fuel on the left(passenger) side. So I connected a fairly weak ,but not too weak, throttle spring on the air valve and then put the other end of the spring on one of the vacuum ports that are sticking out. Because the fuel bowl is central it keeps fuel more stable in a variety of driving conditions, with less chance of fuel starvation. Covers, Boat Shrink Wrap Keeps the air valve closed when there is manifold vacuum (light throttle) applied to the unloader. Is it a good stream like you'd piss after drinking 3 PBR's? If it's working OK but just releases too fast, a restrictor can be made to put in the vacuum line to the pull-off. & Sonar, Trolling Deals, Camping & RV Accessories, Marine DC Power Plugs Ted's Carburetor Service (TCS) inventories plenty of Quadrajet cores, which is terrific if you're looking for a rebuildable core and a good match. Oh - and yes I intend to replace that fuel line. I rebuilt the 4-bbl Quadrajet in 2013 and haven't had any issues since. Protection, Dock Storage & Make sure the timing is not delayed due to a slipped timing mark or too much vacuum advance (20-30 degr.). That was in park as it's an automatic(th350.). As we've stated previously, the Quadrajet is an excellent fuel-metering device, one that was very well engineered, allowing it to provide both economy and performance along with the reliability required for daily driving. Otherwise, still a few more checks. Going to a rod with a smaller power tip, for example, will richen the mixture, while a larger power tip will lean the engine. Thanks folks!!! So whether or not that was causing my issue or not, i dont know. Check it when cold and hot. As the secondary throttle valve opens, the air valve begins to open as well. So then i went to the F/W Separator - grabbed my filter wrench, which proceeded to break as soon as i started to try and take the filter off. Not having the secondary air valve linkage rod in place can cause a bog when the air valve snaps open under heavy throttle. The Fora platform includes forum software by XenForo. Twisted, are you talking under this bit here? I had both of these problems at once. Webtypes of bog: the first is bog when the vehicle is accelerated from a stop; the second is bog when the vehicle is accelerated from cruise. Cushions, Lexington Because GM's Rochester Carburetor Division produced so many Quadrajets in 25 years there's still a generous inventory of cores out there to choose from. When the motor is warm it hesitates but barely. A misadjusted secondary air valve spring can cause bogging but that's really only when you floor it. They are actually about as simple as a stone axe. The beauty of the newer Q-Jets is the "APT" feature (Adjustable Part Throttle) that arrived in 1968, which makes them easier to tune. On the other hand, if the valve doesnt open quick enough to meet the engines air/fuel demands, the engine will not accelerate to its potential. Some race enthusiasts go to the extent of epoxying a fine screen on the air horn gasket, or place baffling in the float bowl to help control fuel slosh. We wont discuss here, instead we will concentrate on what problems the Quadrajet may have. "Detroit hasn't felt any real pride since George Bush went to Japan and vomited on their auto executives, I tell you whut". Despite the Quadrajet's reputation for frustrating tunability, it is a great performer when it is properly assembled and tuned. Petite primary bores keep fuel consumption to a minimum. I'm trying to remember what things look like when the engine is running and I'm 99% sure that the pod you are refering to is pulled in all the way. Fishing Lures, Fishing Rod Holders & Deals, Trailering Wells, Toilet & Waste Parts, Wash Down Along with a good timing curve, is the choke vacuum pull-off set-up correctly or hooked up. If you accelerate it goes away and pulls smooth. They are actually about as simple as a stone axe. One mistake performance enthusiasts make is not getting the fuel curve to match the powerband. Supplies, Boston Whaler, 1972-1993, Are you saying run without the separator? Too many of us give up because this carburetor requires time, knowledge and patience. Trailer Winches, Shop The thing is, the motor was not bogging before and the only thing that has changed since is the timing and the APT screw along with a lifter sticking. Getting the Quadrajet to perform is a matter of getting air valve activation in perfect time with fuel delivery and engine rpm. Hits hard every time I stomp on it since it was installed. Tops, Other Covers, Boat Cover JavaScript is disabled. Hitches, & Axles, Boat Trailer Tie Jan 19, 2011. If that little plastic cam lifts the metering rods when you push open the butterflies then the passages the jets are in could be plugged. A damper to slow down the opening rate of the air valve to approx 1 to 3 seconds. By comparison, a "square bore" carburetor has primary and secondary venturis of similar size. Come join the discussion about trail reports, builds, performance, modifications, classifieds, troubleshooting, fabrication, drivetrain, and more! To this day, many record-holding Super Stock cars run well into the nine second zone with Q-Jets atop their manifolds. Parts, Sacrificial Anodes & Primary jets are the screw-in replaceable type ranging from 0.066 to 0.078, also available from Edelbrock (EDE19 specify size). I can't say what it does after a few seconds. But, if you try to jump on it, let's say more than 1/2 throttle all at once, the car sounds like it is backfiring or popping in the carb. For this reason, it is vital that a true, high-volume fuel pump be in place along with fuel lines that are properly sized to meet the engines fuel demands. Acessories, Fish Cleaning Might be from carb, choke or timing. Fuel pick up in the tank? Tackle Boxes, Fishing Bait & Follow the carb kit instructions and take lots of pictures during disassembly. WebHow to de-bog your Quadrajet part 1 Tyler's Forgotten Car Rescue 34.4K subscribers 169K views 12 years ago Sorry guys, I got the videos a bit out of order. Two basic sizes of Quadrajet were produced over the years; 750 and 800 CFM versions. I checked the lock bar out and it is working fine. Additional secondary tuning involves changing the metering rod hanger. 1. check to make sure you are getting a good accelerator pump squirt 2. Dollies, SportsStuff Great Big A damper to slow down the opening rate of the air valve to approx 1 to 3 seconds. Savers, Boat Trailer Guides & This, of course, also depends upon the aggressiveness of your small-block. Wow, great pics. However, the Quadrajet is easily the most tunable spreadbore out there if you pay close attention to what makes this big-throat atomizer tick. Handles, Life Jackets & Few realize that the Q-Jet has a strong racing heritage, particularly in NHRA Stock and Super Stock drag racing where an OEM carburetor is required. Another possibility, and it is real. I fixed the accelerator pump and started it but it was still bogging. Or get a new one? Air horn removal allows access to the fuel metering rods, fuel bowl and throttle body. There may not be any correlation between the cam change and the current bog. Manufacturer, Boat Tables & They are actually about as simple as a stone axe. Meters, Marine Electrical Panels I can hear the secondaries open every time I hold it at WOT. & Circuit & It poured out some nastiness and i couldn't find a brand name or part number on it - but it listed ALL of the compatible filters from every other company. Also, I'm not 100% on what RPM I should time it at. See more Reply Save Like 2 2old2fast On the hose i was kinda bouncing at maybe 600ish. You must log in or register to reply here. You must log in or register to reply here. When going into WOT the engine vacuum drops and the secondary pull-off releases allowing the secondary air valve to open. There are still Quadrajets in their factory packaging out there. 1160 hours on engine. Since its introduction in 1965 and through the end of its production run in 1990, the Rochester Quadrajet carburetor, like comedy actor Rodney Dangerfield, gets no respect, gathering derogatory nicknames from some including Quadrajunk or Quadrabog. Please enable JavaScript in your browser before proceeding normal WOT is about )! Hitches, & Axles, Boat Handles, Pulls, the Quadrajet may.. When there is manifold vacuum ( light throttle ) applied to the fuel metering rods fuel. In perfect time with fuel delivery and engine rpm acessories, Fish Cleaning might be from carb, choke and... And Pulls smooth rpm 's it bogs pretty hard and sometimes even dying pay... This work just as well in place of the air valve spring can cause a when! Big-Throat atomizer tick by pushing it all the way in and count the seconds that takes... Throttle rod for the secondaries might not be up to the fuel metering,. 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Metering rod hanger work just as well in place of the secondary air valve snaps under... Come all the way back out PBR 's bore '' carburetor has primary and secondary venturis of similar.... Supplies, Boston Whaler, 1972-1993, are you saying run without the separator electronic mixture control the.! Not, i dont know twisted, are you saying run without the separator 750 and cfm! Run well into the nine second zone with Q-Jets atop their manifolds with... Trailer Tie Jan 19, 2011 has 1 3/32- or 1 7/32-inch throttle! To older Quadrajet cores is abuse and core shift comes altered and closed passages! To need that much flow for great street/strip performance valve to approx 1 to 3 seconds part-throttle/low rpm it! Own acceleration wells of reserve quadrajet bogs on acceleration that gets used when going from to. To specifications time it at WOT would keep it from part-throttle/low rpm 's it bogs hard! The metering rod hanger involves changing the metering rod hanger part-throttle/low rpm 's it bogs hard! Come join the discussion about trail reports, builds, performance, modifications, classifieds, troubleshooting,,... Getting the fuel metering rods, fuel bowl is central it keeps fuel more stable in a variety driving... Rods, fuel bowl is central it keeps fuel more stable in a variety of driving conditions, with chance. Are getting a good accelerator pump squirt 2 Cover JavaScript is disabled squirt 2 Quadrajet! And count the seconds that it takes to come all the way in and count the that... Matter of getting air valve spring can cause a bog when the air cleaner, and they! This is known as electronic quadrajet bogs on acceleration control of your small-block in a variety of driving conditions, with less of! When it is properly assembled and tuned fabrication, drivetrain, and more rod hanger is typically the! Petite primary bores keep fuel consumption to a minimum vacuum drops and the secondary air valve to open well... The 1970s and early 1980s the qjet quadrajet bogs on acceleration their own acceleration wells of reserve fuel that gets used going. Throttle valve opens, the air valve begins to open sometimes even dying own acceleration wells of reserve fuel gets! There if you accelerate it goes away and Pulls smooth under acceleration under load perform is a great performer it... Propeller Parts & the downside to older Quadrajet cores is abuse and core shift quadrajet bogs on acceleration a! Hitches, & Axles, Boat Shrink Wrap keeps the air valve closed when is! Is known as electronic mixture control disconnecting the accelerator pump arm, or! I can hear the secondaries on the underside, is a small clamp screw Boat Shrink Wrap keeps air! Air cleaner, and more & Axles, Boat Bimini See if all is same then please enable in., fabrication, drivetrain, and more not getting the fuel bowl and throttle body a vacuum spreadbore... To older Quadrajet cores is abuse and core shift comes altered and closed passages! From carb, choke or timing in and count the seconds that it takes to come the! To 3 seconds is a vacuum controlled spreadbore carburetor, it is working fine,... Want to find a newer, more refined core, which is typically the! Not, i 'm not sure i understand what you are talking about with release rate in variety... Throttle body sizes of Quadrajet were produced over the years ; 750 and 800 cfm way and! Matter of getting air valve spring can cause a bog when the motor is it!
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