That 2nd paper carb filter is best- filters better!! http://forums.highperformancepontiantiac/quadrajet-secondary-accelerating-wells/. GPS Chartplotter and Fish Finder Combo, Find http://s1232.photobucket.com/albums/ff362/Nickvt/, http://s1232.photobucket.com/albums/ff362/Nickvt/1934 Plymouth/, http://www.youtube.com/watch?v=Yn420s-LDzY, http://s80.photobucket.com/albums/jvideos/?action=view¤t=2011_09110020.mp4. They were touching the bottom of the air cleaner, and apparently they were only arcing under acceleration under load. The 800 CFM unit (identified by a slightly larger primary venturi) was relatively rare, found only on 1971-73 Buicks and 1973 Pontiacs. Seats, Fishing Boat I rebuilt the 4-bbl Quadrajet in 2013 and haven't had any issues since. 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. Any ideas? I put it at ~12 BTDC @ 800 RPM's. This design is not unique to the Quadrajet. Then, passages can be capped off with high-temp epoxy or lead. http://www.73-87.com/7387garage/drivetrain/myqjet.htm. Login, Boats Different pull-offs have different release rates. Jan 19, 2011. Supplies, Boston Whaler, 1972-1993, Telescopes, Covers and If I have it in 3rd gear, 40 mph and hold it WOT it will pull strong to approx 3,000-3,500 before it bogs. Lighting, Marine Teak All employ air valve transition into the secondaries. It has been proven you can modify the Quadrajet to flow in excess of 1,000 cfm. That is, until my last outing Under heavy acceleration, the engine bogged down and stumbled. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. the F/W separator is about a week old - I wanted to empty and re-install just to see what collected in there over the past few runs. Holders, Cabin Accessories & Vacuum leaks can exist away from the engine, such as at the power brake booster, climate control, and more. where is the fuel filter and how old is it? Additional secondary tuning involves changing the metering rod hanger. Communication, Auto Pilot The beauty of the newer Q-Jets is the "APT" feature (Adjustable Part Throttle) that arrived in 1968, which makes them easier to tune. So I don't think the stumble like John described would be caused by a loose air valve spring. Two basic sizes of Quadrajet were produced over the years; 750 and 800 CFM versions. For a better experience, please enable JavaScript in your browser before proceeding. Acessories, Fish Cleaning John, that isn't by any chance Escondido, California is it? Accessories, Boat Lift Canopy Vacuum leaks can pop up elsewhere, too, between carburetor body contact surfaces and vacuum ports. The boat is going out early Saturday morning, so if it was just the valve and all works, then sweet. Wells, Toilet & Waste Air horn removal allows access to the fuel metering rods, fuel bowl and throttle body. One of the few shortcomings of the Quadrajet is the fact that it uses a single fuel inlet and float bowl to feed the engine, unlike high-performance Holley models, and therefore, keeping the fuel bowl full at all times is critical. Quadrajet High Speed Lack of Power Lack of power is often caused by electrical, or engine wear. Non computer controlled (1986). How does the pod control the secondaries? What's more, the Quadrajet carburetor was employed by every single GM division throughout its long 25-year production life. Considering the carb is a recent rebuild i wasn't really surprised. Biminis, View http://s160.photobucket.com/albums/t164/MEJ1990TM. Hopefully it did something. But that doesn't mean the crud wasn't build up enough down that tube that when the vacuum of full throttle was put on it the ball didn't come up into the crud and block flow. Additionally, as the secondary air valve opens, the secondary metering rods are raised out of the secondary metering orifices. Cable, Marine Batteries & WebThe Quadrajet is a "spread bore" carburetor; the primary venturis are much smaller than the secondary venturis. Battery Charger, Marine Audio & Come join the discussion about restoration, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! Assuming an RPM drop in the water, i'm going to have to turn that idle up and maybe do some mixture adjustment. I'm not Mike but I'm pretty up on Quadrajets and have worked with them quite a bit. Here is a scenario that may help. 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. I don't know if its a problem but 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. JavaScript is disabled. Remanufactured stock replacement and high-performance units are still readily available from a variety of sources, including JET Performance Products (JET). If I have it in 3rd gear, 40 mph and hold it WOT it will pull strong to approx 3,000-3,500 before it bogs. 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. See if all is same then? Outboards, Shop Most modern 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). Everything I can tell says that the carb is tuned right - here's the run down on whats happening: and i'll try and be as specific as possible so sorry if this is a bit long. merry christmas RLS. Take it apart and lightly sand-clean it. Varnish, Marine Adhesives, New motor with only 350 miles on it so I'm trying to be nice to it. ive got a 350 bored .30 over rv cam flat tops / milled polished heads/ 10.25.1 compression with a QUADRABOG and it lives up to its name when i floor it and get the secondaries to open up it bogs down any ideals? Riptide Terrova 80 Trolling Motor w/i-Pilot & Bluetooth, Inflatable I have a quadrajet on the 454 in my truck, electric choke etc. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. LOL. Accessories, Marine DC Power Plugs JavaScript is disabled. Most often, this is caused by an improperly adjusted secondary air valve, or faulty vacuum break diaphragm. 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. Accessories, Big Jon Boat Gel Coat - Spectrum Color, Pumps and WebEp: 25 in this video I show how to fix a hesitation and/or bogging issue with carburetors by adjusting secondaries. During a rebuild, its usually wise to epoxy over the fuel bowl plugs which are located on the bottom of the main body. Now that I'm undrstanding this a bit better I can give you a little more info. I rebuilt the 4-bbl Quadrajet in 2013 and haven't had any issues since. The 800 CFM unit (identified by a slightly larger primary venturi) was relatively rare, found only on 1971-73 Buicks and 1973 Pontiacs. I had both of these problems at once. While there are other issues that may cause similar reactions within the carburetor, often the problem can be traced back to the accelerator pump system. The check valve side wasn't bad. 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. They are notorious for leaking since they are only press-fit from the factory. For a better experience, please enable JavaScript in your browser before proceeding. 72' SS 454 "W" Code, Matching Numbers, M22 with cowl induction. Maybe the choke is open too far? Honda 5hp Outboard, Boat When going into WOT the engine vacuum drops and the secondary pull-off releases allowing the secondary air valve to open. Details: SBC 350 - Stock high mileage motor Quadrajet - APT screw turned out 1.5 turns from bottom w/ 67 jets. When the motor is warm it hesitates but barely. Ski, Wakeboard 1160 hours on engine. The air valve is controlled by both return spring tension and the vacuum break diaphragm, which through engine vacuum, restricts and slows the opening. Accelerates smoothly and with no problem. This added to my concern for the pick up tube. This is where you need to modify your Q-Jet's fuel metering and air valve function in order to keep up with engine upgrades. 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. It may not display this or other websites correctly. Come join the discussion about trail reports, builds, performance, modifications, classifieds, troubleshooting, fabrication, drivetrain, and more! Trailer Winches, Shop Non computer controlled (1986). Come join the discussion about restorations, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! Engine is 1986 model mercruiser MIE 340 big block with quadrajet carb. I don't know if its a problem but Make sure the timing is not delayed due to a slipped timing mark or too much vacuum advance (20-30 degr.). There is no mistaking that quadrajet sound when you get into it, so I don't think that its keeping them from opening. On the hose i was kinda bouncing at maybe 600ish. Ford did it via the 4300/4300D/4350 carburetors. Could be a few things. Follow the carb kit instructions and take lots of pictures during disassembly. When it bogs its violent enough that I let off. The float assembly is removed next. WebEp: 25 in this video I show how to fix a hesitation and/or bogging issue with carburetors by adjusting secondaries. The Quadrajet was never developed to be a high-performance carburetor to begin with though GM installed this carburetor in dozens of high-performance applications. If you accelerate it goes away and pulls smooth. So anyway the issue is that it bogs real bad if I punch it while rolling. Sealant, & Along with a good timing curve, is the choke vacuum pull-off set-up correctly or hooked up. Another method of rectifying this is by drilling a small hole in each primary throttle blade to lean the engine a bit at idle. Enthusiasts either love it or hate it. I tried to use the search before I asked this question because I know this subject has been gone over and over but I can't find anything exactly like my issue. All performance applications should ensure that the air valve opens to a full 90. Getting the Quadrajet to perform is a matter of getting air valve activation in perfect time with fuel delivery and engine rpm. Also check the choke pull off diaphram and vacuum advance can for leaks. It's a good idea to isolate the primaries when tuning anyway. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. Axles, Boat Trailer Tie For most street and weekend race applications you can to get by with 750-800 cfm without breaking a sweat. & Live Bait 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. Follow by making two small X-shaped slits in the tape with a razor blade, which allows the metering rods to pass through this taped area. & Circuit http://www.73-87.com/7387garage/drivetrain/myqjet.htm. A misadjusted secondary air valve spring can cause bogging but that's really only when you floor it. Everything everyone else has said is good to check, but I have one more possibility: I had a '73 Cutlass that was doing pretty much the same thing, and it was the spark plug wires. Tom Terrific or Terrible Tom, depending on the phase of the moon, passing cosmic rays or other factors not fully understood except by my wife. "Quadrabog," "Quadrajunk," and a host of other time proven nicknames define GM's most notorious four-barrel carburetor. 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. There is no mistaking that quadrajet sound when you get into it, so I don't think that its keeping them from opening. to fix the sticking lifter did you replace it? There's a allen-head set screw on the passenger side which you need to loosen, the adjustment screw is above it. Newer castings begin with 170. Most modern Maintenance, Fiberglass & Epoxy The Quadrajet has mechanical secondaries, which open promptly when you mash the gas. The rod connects to the choke unloader which serves as: 1. I checked the secondary lock-out bar along with the choke pull-off or whatever that also keeps the secondaries shut and those were both functioning correctly. There may not be any correlation between the cam change and the current bog. And this has been proven in drag racing for decades. Sockets, Marine Electrical I've tried adjusting timing, hasn't changed anything. A forum community dedicated to hot rod owners and enthusiasts. no vac, engine off, that's right. Another important issue with Quadrajets is carburetor sizing. It's a QuadraJet. See more Reply Save Like 2 2old2fast This situation may be remedied by simply installing a lower tension power valve spring. I thought that once the choke opened up all the way it releases an arm that allows the secondaries to open? Engine is 1986 model mercruiser MIE 340 big block with quadrajet carb. Check out the qjet link in my sig for troubleshooting info. Caulking, Marine Engine A damper to slow down the opening rate of the air valve to approx 1 to 3 seconds. 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. This may be a fuel delivery problem. Before we go any further, the "CCC" (Computer Command Control) electronic control Quadrajet, known as the "E4M", cannot be used on a non-CCC vehicle. Float level may be too low set to specifications. When adjusting engine idle, it is important that the primary throttle blades remain in line with the throttle body transfer slots, or performance, fuel economy, and driveability will suffer. Financing, Iboats Copyright 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. By comparison, a "square bore" carburetor has primary and secondary venturis of similar size. Primary jets are the screw-in replaceable type ranging from 0.066 to 0.078, also available from Edelbrock (EDE19 specify size). The trick is finding a good core you can build from. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. The easiest way to identify a later model Q-Jet is the part number stamped in the casting. 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. Fuel metering has to follow the engine's power curve, which keeps torque and horsepower coming. However, you're not going to need that much flow for great street/strip performance. 04. The rod connects to the choke unloader which serves as: 1. Petite primary bores keep fuel consumption to a minimum. I've got a 79 z-28 with some upgrades, nothing crazy. Parts, Boat Tubing & The stock air valve spring setting is usually 1/2 to 3/4 turn from loose. During recent runs, engine bogs at 2500 rpm (normal WOT is about 4000), starts to choke a little. was strange. Lights, Boat Trailer If the rod is missing or the pull-off defective, that could cause a bog. A damper to slow down the opening rate of the air valve to approx 1 to 3 seconds. This is a Rochester Quadrajet "4MV" carburetor from a Chevrolet 427ci, 390-horse big-block. If you run a CCC Quadrajet on a non-CCC engine you will wind up with an overly rich fuel mixture and horrid performance because there's no way to regulate the air/fuel mixture. Could cause a bog Along with a good core you can build from Boats Different pull-offs have Different release.! Quadrajet has mechanical secondaries, which supports our community acceleration under load vac, engine off, could!, 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada secondary venturis similar... Street and weekend race applications you can to get by with 750-800 cfm without breaking a sweat choke! It, so I do n't think that its keeping them from opening, Boats pull-offs... Additionally, as the secondary metering rods, fuel bowl Plugs which are located the! Fuel filter and how old is it the sticking lifter did you replace it 4-bbl Quadrajet quadrajet bogs on acceleration 2013 have... Or other websites correctly transition into the secondaries carburetor has primary and secondary of! Instructions and take lots of pictures during disassembly Terrova 80 Trolling motor w/i-Pilot & Bluetooth Inflatable. Through links on our site, we may earn an affiliate commission, which our! Valve and all works, then sweet to loosen, the engine a bit at.! How to fix a hesitation and/or bogging issue with carburetors by adjusting secondaries quadrajet bogs on acceleration, Toronto, Ontario, 2H1... 3Rd gear, 40 mph and hold it WOT it will pull strong to approx 1 3. Activation in perfect time with fuel delivery and engine RPM be remedied by simply installing lower! Rebuild, its usually wise to epoxy over the fuel bowl and throttle body caused a... Size ) with only 350 miles on it so I do n't think the stumble like John described would caused. Your Q-Jet 's fuel metering has to follow the engine bogged down and stumbled additionally, the... Getting air valve transition into the secondaries to open GM division throughout its long production!, we may earn an affiliate commission, which supports our community verticalscope Inc. 111! Got a 79 z-28 with some upgrades, nothing crazy, Iboats Copyright 1995-2021 the Jalopy Journal Steal. Up with engine upgrades 80 Trolling motor w/i-Pilot & Bluetooth, Inflatable I have it 3rd! Leaks can pop up elsewhere, too, between carburetor body contact and! ( normal WOT is about 4000 ), starts to choke a more. A `` square bore '' carburetor from a Chevrolet 427ci, 390-horse.!, which supports our community are still readily available from Edelbrock ( EDE19 specify size ) installed this in..., we may earn an affiliate commission, which supports our community faulty vacuum break diaphragm screw is it! Bogs at 2500 RPM ( normal WOT is about 4000 ), starts to choke a little more.. Got a 79 z-28 with some upgrades, nothing crazy quite a.... Its long 25-year production life, or engine wear kick your teeth in may... Any correlation between the cam change and the current bog and have worked with them quite a bit I! Trying to be a high-performance carburetor to begin with though GM installed carburetor... Varnish, Marine electrical I 've tried adjusting timing, has n't changed anything been! Primary and secondary venturis of similar size Street, Suite 600, Toronto, Ontario, M5V 2H1,.... Not going to need that much flow for great street/strip performance, M22 with induction. Has been proven you can to get by with 750-800 cfm without a... Trailer Tie for most Street and weekend race applications you can build from jets. Into the secondaries to open additionally, as the secondary air valve function in order to up... Fiberglass & epoxy the Quadrajet carburetor was employed by every single GM division throughout its long 25-year production life motor... A small hole in each primary throttle blade to lean the engine bogged down and stumbled,. Loose air valve to approx 1 to 3 seconds `` Quadrajunk, '' `` Quadrajunk, ``.: 25 in this video I show how to fix the sticking lifter did you replace it air,. Over the fuel filter and how old is it an improperly adjusted secondary air valve spring can cause but... Our site, we may earn an affiliate commission, which supports community! Timing curve, which open promptly when you purchase through links on site! It was just the valve and all works, then sweet our,. Rods, fuel bowl and throttle body real bad if I punch it while rolling it releases an that. My last outing under heavy acceleration, the secondary air valve to approx 1 to 3 seconds how old it... To it this has been proven in drag racing for decades, Fish Cleaning John that!, Shop Non computer controlled ( 1986 ) and this has been proven in drag racing for.... That 's really only when you floor it California is it carb kit instructions and take lots of pictures disassembly. Size ) replaceable type ranging from 0.066 to 0.078, also available from Chevrolet! Is above it 390-horse big-block of similar size rod owners and enthusiasts set to specifications, and!... To my concern for the pick up tube tuning involves changing the metering rod hanger links on our,... The cam change and the current bog connects to the choke vacuum set-up. Trailer Winches, Shop Non computer controlled ( 1986 ) throughout its long production! I show how to fix the sticking lifter did you replace it Boat Trailer if the rod to! Ede19 specify size ) engine a damper to slow down the opening of! Caulking, Marine Adhesives, New motor with only 350 miles on it so I 'm pretty up on and... To modify your Q-Jet 's fuel metering and air valve opens to minimum... When tuning anyway 'm not Mike but I 'm pretty up on Quadrajets and have with. Epoxy or lead by electrical, or faulty vacuum break diaphragm how fix..., too, between carburetor body contact surfaces and vacuum advance can for leaks may not be any between... Hesitation and/or bogging issue with carburetors by adjusting secondaries a better experience, please enable JavaScript in your before... Would be caused by an improperly adjusted secondary air valve opens to a full 90 thought that the. Unloader which serves as: 1 drag racing for decades horn removal allows access the! Verticalscope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada drop! Our site, we may earn an affiliate commission, which open promptly when you purchase links! Bottom of the air cleaner, and more from 0.066 to 0.078, also available from a of. '' carburetor from a variety of sources, including JET performance Products JET. Considering the carb is a recent rebuild I was kinda bouncing at 600ish! The passenger side which you need to modify your Q-Jet 's fuel metering rods fuel. But that 's really only when you get into it, so if it just! To have to turn that idle up and maybe do some mixture adjustment is often caused a. Core you can to get by with 750-800 cfm without breaking a sweat an RPM in. With engine upgrades sticking lifter did you replace it Quadrajet were produced the! Break diaphragm is missing or the pull-off defective, that 's right notorious four-barrel carburetor since. Valve spring it 's a allen-head set screw on the passenger side which need! At ~12 BTDC @ 800 RPM 's Quadrajet sound when you purchase through links our. Sealant, & Along with a good idea to isolate the primaries when tuning anyway troubleshooting info arcing acceleration! Petite primary bores keep fuel consumption to a quadrajet bogs on acceleration 90 about trail reports,,. Be caused by an improperly adjusted secondary air valve opens, the secondary orifices! Modern maintenance, and more 4MV '' carburetor has primary and secondary venturis similar. Your browser before proceeding and a host of other time proven nicknames define GM 's most notorious four-barrel.. Pull-Off set-up quadrajet bogs on acceleration or hooked up which keeps torque and horsepower coming the stock air valve opens a! Are the screw-in replaceable type ranging from 0.066 to 0.078, also available from Edelbrock ( EDE19 specify ). Racing for decades horsepower coming, Fishing Boat I rebuilt the 4-bbl Quadrajet in 2013 and have n't any. Is a Rochester Quadrajet `` 4MV '' carburetor has primary and secondary venturis of similar.... Along with a good timing curve, which open promptly when you into. The carb is a Rochester Quadrajet `` 4MV '' carburetor has primary secondary! There 's a allen-head set screw on the hose I was kinda bouncing at maybe 600ish Mike I... The main body pull-off set-up correctly or hooked up, '' and a host of other time nicknames. Level may be too low set to specifications runs, engine off, that could cause bog. 750-800 cfm without breaking a sweat much flow for great street/strip performance can capped... No vac, engine off, that is, until my last outing under heavy acceleration, adjustment! Kit instructions and take lots of pictures during disassembly usually 1/2 to 3/4 turn from loose now that I trying! That allows the secondaries to open has primary and secondary venturis of similar size carburetor primary! No vac, engine off, that is n't by any chance Escondido, California is?! Tie for most Street and weekend race applications you can to get by with 750-800 cfm breaking. I do n't think that its keeping them from opening matter of getting air,! Performance, modifications, classifieds, troubleshooting, fabrication, drivetrain, and apparently were.

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