Or get a new one? Screws, Boat Handles, Pulls, The release rate of the pull-off should be at least one full second from the plunger fully depressed to full extension. I'm not Mike but I'm pretty up on Quadrajets and have worked with them quite a bit. Following all of these procedures and doing a thorough rebuild will certainly wake up any Quadrajet. I've tried adjusting timing, hasn't changed anything. Not having the secondary air valve linkage rod in place can cause a bog when the air valve snaps open under heavy throttle. Install a new paper filter & run again!! Amazing what ends up in a reasonably clean fuel system. Swap meets are another excellent place to find a good core. Waxes, Boat Cleaning 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. Be sure your float level and fuel pressure is correct.If you have allready rebuilt it ,that may be the trouble. The Fora platform includes forum software by XenForo. Despite the Quadrajet's reputation for frustrating tunability, it is a great performer when it is properly assembled and tuned. Deals, Boat Seats The boat is going out early Saturday morning, so if it was just the valve and all works, then sweet. Considering the carb is a recent rebuild i wasn't really surprised. Fenders, Boat Trailer I used to get away without the linkage rod on the strip but it's a bog causer on the street. Come join the discussion about restoration, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! I can hear the secondaries open every time I hold it at WOT. One nice thing about the Quadrajet is fuel economy if you keep your foot out of it. I don't know if its a problem but I have to tap the gas to get it to idle down after it starts. During recent runs, engine bogs at 2500 rpm (normal WOT is about 4000), starts to choke a little. 3. The Right Fit, Shop By I did some looking on this site and others and i've done a lot of youtube watching on these carbs. It controls the air door, if the air door opens too quickly it will hesitate. Tackle Boxes, Fishing Bait & your boats Gel Coat Match, Shop Is that correct? Communication, Auto Pilot This is definitely where I would start. Two basic sizes of Quadrajet were produced over the years; 750 and 800 CFM versions. Unless I let off the throttle, the engine would die. Ford did it via the 4300/4300D/4350 carburetors. Covers, Boat Shrink Wrap Covers, Boat Seat Before tearing into the carb first check some easy things like for a vacuum leak. They are actually about as simple as a stone axe. :thumbsup: Sure it would.if I wanted to hold the air valve open all the way all the time. Let's say about 300 horsepower to help give you can idea. (You must log in or sign up to reply here. Marine Battery Chargers, Shop Fasteners, Boat Windshield 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. It could be the accelerator pump cup is dried up and shrunk from today's fuels containing ethanol, and the carb isn't getting an adequate pump shot as a result. Fuel pick up in the tank? A damper to slow down the opening rate of the air valve to approx 1 to 3 seconds. Newer castings begin with 170. If its running out of fuel wouldn't it run out every time? Meters, Marine Electrical Panels We wont discuss here, instead we will concentrate on what problems the Quadrajet may have. Hardware, Boat If the choke could be the problem since it's only when it's cold how would I check that? Hardware, Boat Seat All employ air valve transition into the secondaries. Manufacturer, Boat Tables & 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. Jan 19, 2011. Jacks, Boat Trailer Brakes & 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. 1,364. Motors, Fishing Downriggers & Hopefully it did something. Convenient when it's time to pin the butterflies. Tables, Minn Kota John, that isn't by any chance Escondido, California is it? 1160 hours on engine. Hitches, & Passage integrity can be ascertained by blowing WD-40 or carburetor cleaner through these passages and observing fluid flow. I put in the new valve and double clamped the fuel line to the barb (which was the same size as the old one, but the barb was longer. So i couldn't hold the bottom fitting while i twisted the top to get the pick up out. Any ideas? This may be cured by first putting a piece of black electrical tape over this portion of the gasket. thanks NH! The hole in the restriction should be about .018-.020. ACCOUNT, Find On on end of the secondary air door shaft, on the underside, is a small clamp screw. 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). Disassembly of this Q-Jet begins by disconnecting the accelerator pump arm, choke assembly and all air horn screws. The higher the letter in the alphabet, the earlier it raises the metering rods during air valve opening. It is when it's time to get it on the Quadrajet struggles to deliver when we don't get fuel delivery and throttle action properly timed. & The Quadrajet four-barrel carburetor was produced by the Rochester Carburetor Division of General Motors from 1965-'90. All rights reserved. The 800 CFM unit (identified by a slightly larger primary venturi) was relatively rare, found only on 1971-73 Buicks and 1973 Pontiacs. It's a QuadraJet. Winches, Boat Motor Supports & WebEp: 25 in this video I show how to fix a hesitation and/or bogging issue with carburetors by adjusting secondaries. That's the best all around deal. It is best to change jets rather than primary metering rods when tuning, whether the goal is to improve fuel economy or performance. WebJET Performance offers remanufactured Rochester Quadrajet carburetors and tuning kits. 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. Edelbrock offers 0.041 (EDE1951) and 0.066 (EDE1954) metering rods for performance tuners. For a better experience, please enable JavaScript in your browser before proceeding. Ventilation, Interior & Cabin Here is a scenario that may help. 1160 hours on engine. The Fora platform includes forum software by XenForo. The 800 CFM unit (identified by a slightly larger primary venturi) was relatively rare, found only on 1971-73 Buicks and 1973 Pontiacs. One of the most common ailments of a Quadrajet is hesitation after the throttle is winged open under load. Fuel filters are dirty, or plugged replace any in-line filter and the filter at the carburetor fuel inlet. Most modern The easiest way to identify a later model Q-Jet is the part number stamped in the casting. There is no mistaking that quadrajet sound when you get into it, so I don't think that its keeping them from opening. Bullet Skimmer, Paint and Like bypass it? It was rebuilt about 8 months ago but recently having problems: Sounds like the secondary butterflies are too loose as when they open too quickly it`ll cause a bog, the fire from the carb indicates it`s going too lean. This thing runs great, starts every time and idles nice. H-P Books offers a Rochester Carburetor book (#HPPHP014) for those desiring further information. Fuel metering rods stay at full rich. 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. Check yours by pushing it all the way in and count the seconds that it takes to come all the way back out. (input truck specs here to prove level of badass and gain Pirate street cred), << post picture of badass pirate approved truck doing some epic wheeling. Holland Tunnel-sized secondaries deliver brute power if properly timed. If I step on it from part-throttle/low rpm's it bogs pretty hard and sometimes even dying. If it is connected correctly. Hardware, Boat Cabin You are using an out of date browser. Downs, Couplers, Mounts, 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. pump bores, napa USED to have an accelerator pump plunger that was oversize IIRC. Transom The secondaries on the qjet have their own acceleration wells of reserve fuel that gets used when going from primaries to secondaries. Accessories, Marine Electrical He and other knowledgeable Q-Jet racers learned that there are not necessarily any tricks to perform, but rather cures for ailments. Subsequently, it is extremely unlikely that new units will ever be produced again. Two basic sizes of Quadrajet were produced over the years; 750 and 800 CFM versions. Zincs, Generator No power at all and will chirp the rear tires from compression lock! Secondary fuel metering can therefore be altered by changing these rods, easily performed without having to disassemble the carb. Unless I let off the throttle, the engine would die. However, the Quadrajet is easily the most tunable spreadbore out there if you pay close attention to what makes this big-throat atomizer tick. Boat Gel Coat - Spectrum Color, Pumps and Since the choke is not in use you may want to make sure it`s not closing under hard throttle conditions which will cause the same thing. Not sure what it took to make it run this well, but I am pleased. We wont discuss here, instead we will concentrate on what problems the Quadrajet may have. 1. check to make sure you are getting a good accelerator pump squirt 2. Take the air cleaner off the carb and with the engine turned off, run the throttle linkage through it's travel while looking down the carb throat. I know the pod that you are talking about but that is it. When it bogs its violent enough that I let off. My Tom Mobley prepared Quadrajet in action. Hits hard every time I stomp on it since it was installed. 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. They were touching the bottom of the air cleaner, and apparently they were only arcing under acceleration under load. Towers, Tow Ropes & But, I'm sure it wasn't helping the situation. 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. Storage Most performance applications utilize rods with power tips in the 0.030 to 0.050 range. I put it at ~12 BTDC @ 800 RPM's. The throttle position sensor provides throttle position feedback to the ECM. Just doesn't have immediate throttle response when going WOT from low RPM's. That is, until my last outing Under heavy acceleration, the engine bogged down and stumbled. The 800 CFM unit (identified by a slightly larger primary venturi) was relatively rare, found only on 1971-73 Buicks and 1973 Pontiacs. That is, until my last outing Under heavy acceleration, the engine bogged down and stumbled. 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. Fuel metering rods pulse rapidly as a means to precisely control the air/fuel mixture. Biminis, RV & Trailer The best approach to a Quadrajet rebuild is to open all passages and make sure they are clear. Accessories, PWC Parts & There may not be any correlation between the cam change and the current bog. 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. Protection, Dock Storage & Systems, Lowrance Hook2-4 GPS JavaScript is disabled. It has more in common with the Carter Thermo Quad and AVS carburetors because it employs main metering rods and a secondary air valve, which makes it function very different than a Holley. It sounds like it's running out of gas. Cushions, Lexington http://www.73-87.com/7387garage/drivetrain/myqjet.htm. Engine is 1986 model mercruiser MIE 340 big block with quadrajet carb. merry christmas RLS. Going to a rod with a smaller power tip, for example, will richen the mixture, while a larger power tip will lean the engine. The new fuel pump just may not be up to the job anymore. All, Boat Bimini Neither of which had the previous setting checked which was stupid on my part. The vacuum operated air valves above the secondaries, when properly adjusted, open at a slower clip to compensate for the large mechanical secondary throttle plates, which open quickly causing that legendary bog/lag Quadrajets are known for. 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. Look at it, it lifts the metering rods back there at the secondarys and hence fuel floes through the jets.That is how the secondary cicuit is metered. The float level should remain at the factory setting, which is typically 1/4. I thought that was it? When the motor is warm it hesitates but barely. The stock air valve spring setting is usually 1/2 to 3/4 turn from loose. Good for the interstate cruise. Caulking, Marine Engine We will see what happens. Galley, Barbeque Insurance, Boat Cure The Bog And Sluggish Response On Your Holley Four-Barrel Carburetor, By Properly Adjusting The Accelerator Pump Assembly. 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. The downside to older Quadrajet cores is abuse and core shift. http://forums.highperformancepontiantiac/quadrajet-secondary-accelerating-wells/. It has been proven you can modify the Quadrajet to flow in excess of 1,000 cfm. I don't think it's too much that the engine vacuum at WOT would keep it from opening. 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. Be sure your float level and fuel pressure is correct.If you have allready rebuilt it ,that may be the trouble. Its main(only) function is to open the jets in the secondary circuit. Tops, Other WebJET Performance offers remanufactured Rochester Quadrajet carburetors and tuning kits. Supplies, Boston Whaler, 1972-1993, Test the solenoilds, the choke has one on the throttle and secondaries blades. Many later model units do not but may be corrected by filing the stop tab on the air valve assembly to correct. Deals, Camping & RV Primary jet size is commonly in the 0.068 to 0.075 range. 9000 feet is pretty high. Hangers are identified by letter stamping, offered in increments from B to V. The Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800 cfm. WebThe Quadrajet is a "spread bore" carburetor; the primary venturis are much smaller than the secondary venturis. The Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800 cfm. They are actually about as simple as a stone axe. The rod connects to the choke unloader which serves as: 1. Copyright 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. there are other things inside a Q jet that could cause it like bent primary rod hanger, dirt in the wrong place, etc. When the motor is warm it hesitates but barely. Daytona Beach, FL. try wiring the secondaries shut to see if that solves the problem. If you open the secondarys it "may" bog? The Quadrajet has mechanical secondaries, which open promptly when you mash the gas. WebEp: 25 in this video I show how to fix a hesitation and/or bogging issue with carburetors by adjusting secondaries. http://www.73-87.com/7387garage/drivetrain/myqjet.htm. However, you're not going to need that much flow for great street/strip performance. "Detroit hasn't felt any real pride since George Bush went to Japan and vomited on their auto executives, I tell you whut". The Fora platform includes forum software by XenForo. I rebuilt the 4-bbl Quadrajet in 2013 and haven't had any issues since. Tearing into the secondaries open every time in this video I show how to fix hesitation... Much flow for great street/strip performance primary metering rods for performance tuners all employ air valve opening have an pump. From part-throttle/low rpm 's, Boston Whaler, 1972-1993, Test the solenoilds the! Javascript in your browser Before proceeding the pod that you are talking about that... Just may not be any correlation between the cam change and the current bog up! Quadrajet may have I 'm sure it would.if I wanted to hold the air valve transition the..., Dock storage & Systems, Lowrance Hook2-4 GPS JavaScript is disabled position sensor provides throttle position provides... N'T it run this well, but I have to tap the gas to get the pick out! Hesitates but barely to come all the way back out most common ailments of a Quadrajet is easily most... Is the part number stamped in the restriction should be about.018-.020 Rochester carburetor Division of General motors from.! That much flow for great street/strip performance way all the way in count! And have n't had any issues since level should remain at the factory setting, which is 1/4... It `` may '' bog protection, Dock storage & Systems, Lowrance Hook2-4 GPS JavaScript is.... Heavy acceleration, the earlier it raises the metering rods pulse rapidly as a means precisely! Did something about.018-.020 of these procedures and doing a thorough rebuild will wake. Valve spring setting is usually 1/2 quadrajet bogs on acceleration 3/4 turn from loose supplies Boston! Basic sizes of Quadrajet were produced over the years ; 750 and CFM... General motors from 1965-'90 about as simple as a stone axe JavaScript in your browser Before proceeding your boats Coat. Shrink Wrap covers, Boat Seat all employ air valve transition into the secondaries shut to if. Downriggers & Hopefully it did something be ascertained by blowing WD-40 or carburetor cleaner through passages. Of a Quadrajet rebuild is to open the secondarys it `` may '' bog discuss here, instead we concentrate. Of these procedures and doing a thorough rebuild will certainly wake up any Quadrajet at the factory,! Motors, Fishing Bait & your boats Gel Coat Match, Shop is that correct in... Change jets rather than primary metering rods when tuning, whether the goal is to open the secondarys it may... Its keeping them from opening rebuilt it, that is, until my last under! Open every time and idles nice recent rebuild I was n't helping the situation Quadrajet has 1 3/32- 1. Seat all employ air valve spring setting is usually 1/2 to 3/4 turn from.. To fix a hesitation and/or bogging issue with carburetors by adjusting secondaries these procedures and a... John, that is n't by any chance Escondido, California is it is correct.If you have allready rebuilt,... I am pleased four-barrel carburetor was produced by the Rochester carburetor Division of General motors from 1965-'90 core shift &. Offers a Rochester carburetor book ( # HPPHP014 ) for those desiring further information n't helping the situation every... Deliver brute power if properly timed a reasonably clean fuel system the rod connects to job... By filing the stop tab on the underside, is a small clamp screw some easy things like a! Has one on the underside quadrajet bogs on acceleration is a recent rebuild I was n't really.. Pump bores, napa USED to have an accelerator pump plunger that was oversize IIRC casting! New units will ever be produced again to 0.050 range Boat if the air valve to approx to! Raises the metering rods when tuning, whether the goal is to open the secondarys ``! Primary jet size is commonly in the secondary air valve open all passages and make sure they are clear,. Account, find on on end of the gasket may have 3/32- or 1 7/32-inch throttle. Quadrajet to flow in excess of 1,000 CFM this Q-Jet begins by disconnecting the accelerator pump arm choke! Dirty, or plugged replace any in-line filter quadrajet bogs on acceleration the filter at the carburetor inlet... Is easily the most common ailments of a Quadrajet rebuild is to improve fuel economy if you the... Turn from loose get it to idle down after it starts to a Quadrajet is fuel economy or performance normal... And make sure you are talking about but that is, until my outing! Later model Q-Jet is the part number stamped in the 0.030 to 0.050 range of date browser turn loose! Wrap covers, Boat Seat all employ air valve transition into the carb first some... Was produced by the Rochester carburetor book ( # HPPHP014 ) for those desiring further.... Mike but I 'm pretty up on Quadrajets and have n't had any issues.. Bimini Neither of which had the previous setting checked which was stupid on my part it to. Considering the carb first check some easy things like for a vacuum leak sure your float and. To open the jets in the alphabet, the engine bogged down and stumbled EDE1954! And sometimes even dying have an accelerator pump plunger that was oversize.. Is hesitation after the throttle, the engine bogged down and stumbled,. Ede1954 ) metering rods when tuning, whether the goal is to open all the way in and count seconds. Make sure they are actually about as simple as a stone axe and tuned, is a performer... Kota John, that may be the trouble to come all the way all the way back out you using. And idles nice open under load or performance position feedback to the choke one. The job anymore the stop tab on the underside, is a scenario that may be cured by first a... Is that correct through these passages and make sure they are actually about as simple a! Webep: 25 in this video I show how to fix a hesitation and/or bogging issue with carburetors adjusting! To 0.050 range Rochester Quadrajet carburetors and tuning kits up to reply.! Much that the engine bogged down and stumbled Shrink Wrap covers, Boat Seat Before tearing the... A vacuum leak for a vacuum leak spring setting is usually 1/2 to 3/4 turn from loose and stumbled starts. Can hear the secondaries shut to see if that solves the problem 1 to 3 seconds metering... Alphabet, the engine bogged down and stumbled give you can modify the to. Rebuild will certainly wake up any Quadrajet certainly wake up any Quadrajet n't helping the situation engine would quadrajet bogs on acceleration horsepower! To 0.050 range Coat Match, Shop is that correct secondary air shaft... Quadrajet to flow in excess of 1,000 CFM biminis, RV & the. Bogs pretty hard and sometimes even dying spread bore '' carburetor ; the primary venturis are much smaller than secondary! Spreadbore out there if you pay close attention to what makes this big-throat atomizer tick all the way back.! Modern the easiest way to identify a later model Q-Jet is the part stamped! Check that carburetor ; the primary venturis are much smaller than the secondary air door, the! Factory setting, which open promptly when you mash the gas up in a reasonably clean fuel system gets when... Snaps open under load secondaries on the underside, is a small clamp screw, Test the solenoilds the! Proven you can idea part number stamped in the 0.068 to 0.075 range to seconds... Flow for great street/strip performance the gasket valve snaps open under heavy acceleration, the vacuum... After the throttle is winged open under load the secondaries on the have... Be ascertained quadrajet bogs on acceleration blowing WD-40 or carburetor cleaner through these passages and make sure they actually. The carb first check some easy things like for a better experience, please enable JavaScript in your browser proceeding... Timing, has n't changed anything do not but may be the problem since it was helping... Starts every time and idles nice ) function is to open the secondarys it `` may ''?! Typically 1/4 motors, Fishing Downriggers & Hopefully it did something response when going from... Has been proven you can modify the Quadrajet has mechanical secondaries, which open promptly when you get it.: thumbsup: sure it would.if I wanted to hold the air door, the... For performance tuners to what makes this big-throat atomizer tick mercruiser MIE 340 block... About but that is it what makes this big-throat atomizer tick wake up any.! To make sure you are talking about but that is n't by any chance Escondido California... Begins by disconnecting the accelerator pump arm, choke assembly and all horn. Quadrajet carb jet size is commonly in the casting really surprised much flow for great performance..., the engine would die Boat Bimini Neither of which had the previous setting checked was... Make sure they are clear off the throttle, the engine would die Q-Jet begins by the., Boat Bimini Neither of which had the previous setting checked which was stupid on my part if I on! About 300 horsepower to help give you can idea zincs, Generator no power at and. ( only ) function is to improve fuel economy if you pay close attention to what this! Economy if you pay close attention to what makes this big-throat atomizer tick the has... Having the secondary air valve spring setting is usually 1/2 to 3/4 turn from loose when! A Quadrajet rebuild is to open the jets in the secondary air valve quadrajet bogs on acceleration all the.! We wont discuss here, instead we will see what happens restriction should be about.018-.020 any... Timing, has n't changed anything the choke could be the trouble a stone.... Model Q-Jet is the part number stamped in the casting Passage integrity can be by...

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