For a better experience, please enable JavaScript in your browser before proceeding. BUT even if the air valve is completely loose it won't cause a bog till the secondary butterflies are opened at the "tip in" point. That is, until my last outing Under heavy acceleration, the engine bogged down and stumbled. And this has been proven in drag racing for decades. It has been proven you can modify the Quadrajet to flow in excess of 1,000 cfm. Getting the Quadrajet to perform is a matter of getting air valve activation in perfect time with fuel delivery and engine rpm. 3 things I'd check John: ( other than a big vaccum leak which would do this). Details: SBC 350 - Stock high mileage motor Quadrajet - APT screw turned out 1.5 turns from bottom w/ 67 jets. The thing that is puzzling me is that it does not do it every time. Helm Seats, Shop When you purchase through links on our site, we may earn an affiliate commission, which supports our community. I have a quadrajet on the 454 in my truck, electric choke etc. The 0.135 valve works well in most drag or circle track applications, while Edelbrock also offers a 0.145 high-flow assembly (EDE1980) for fuel-thirsty machines. I am no expert on the Q-jet, so I'd like some thoughts on adjustment. Acessories, Fish Cleaning The power Piston is stuck in the q jet. You are using an out of date browser. 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. 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. I just went through this problem myself recently. For a better experience, please enable JavaScript in your browser before proceeding. So whether or not that was causing my issue or not, i dont know. Protection, Ladders, Steps, & Furniture, Boat Seat Pedestals & Terminals, Marine Fuse Blocks & The higher the letter in the alphabet, the earlier it raises the metering rods during air valve opening. Different pull-offs have different release rates. Deals, Camping & RV WebEp: 25 in this video I show how to fix a hesitation and/or bogging issue with carburetors by adjusting secondaries. Otherwise, still a few more checks. Come join the discussion about trail reports, builds, performance, modifications, classifieds, troubleshooting, fabrication, drivetrain, and more! Telescopes, Covers and Neither of which had the previous setting checked which was stupid on my part. I've tried adjusting timing, hasn't changed anything. All employ air valve transition into the secondaries. 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? Motors, Fishing Downriggers & New motor with only 350 miles on it so I'm trying to be nice to it. Oh - and yes I intend to replace that fuel line. I've tried adjusting timing, hasn't changed anything. Covers, Boat Cover I rebuilt the Quadrajet and the car starts and runs very smooth. Big-blocks want 800 cfm. I checked the lock bar out and it is working fine. Accelerates smoothly and with no problem. If the rod is missing or the pull-off defective, that could cause a bog. Holland Tunnel-sized secondaries deliver brute power if properly timed. Most performance applications utilize rods with power tips in the 0.030 to 0.050 range. Older Quadrajet part numbers begin with 702 and 704. Keeps the air valve closed when there is manifold vacuum (light throttle) applied to the unloader. Make sure the secondary accelerator wells are filling. Combos, Fishing Tools & 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. One mistake performance enthusiasts make is not getting the fuel curve to match the powerband. Come join the discussion about restorations, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! Now that I'm undrstanding this a bit better I can give you a little more info. I kinda miss them, ok i unhooked my choke that closes the secondaries because that was shutting and locking my secondaries and that helped a little bit but it still bogs down. Meters, Marine Electrical Panels Some black smoke out of the exhaust. 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. 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. It may not display this or other websites correctly. Timed to ~6 BTDC with vacuum advance disconnected.HEI distributor Elevation is 9,000ft. Copyright 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. The Fora platform includes forum software by XenForo. "Detroit hasn't felt any real pride since George Bush went to Japan and vomited on their auto executives, I tell you whut". That is, until my last outing Under heavy acceleration, the engine bogged down and stumbled. So i couldn't hold the bottom fitting while i twisted the top to get the pick up out. Check eBay, Craigslist and Racing Junk websites for options. For a better experience, please enable JavaScript in your browser before proceeding. All, Anchor & Non computer controlled (1986). Because the Quadrajet is so versatile, it is easy to find a suitable core for your GM V-8 project. Maintenance, Boat Cleaners & Bullet Skimmer, Paint and Thanks folks!!! I had both of these problems at once. Not having the secondary air valve linkage rod in place can cause a bog when the air valve snaps open under heavy throttle. High Back Reclining Helm Seat, Cabin and During recent runs, engine bogs at 2500 rpm (normal WOT is about 4000), starts to choke a little. Accelerates smoothly and with no problem. I am no expert on the Q-jet, so I'd like some thoughts on adjustment. Make sure the dist vacuum advance is connected to full manifold vacuum. Boat, Boat Buyers Plumbing, Fresh Water Boat Harware, Marine Nuts, Bolts, & Might be from carb, choke or timing. Insurance, Boat Details: SBC 350 - Stock high mileage motor Quadrajet - APT screw turned out 1.5 turns from bottom w/ 67 jets. At heavy throttle, manifold vacuum goes away and the unloader relaxes, allowing the air valve to open via the linkage rod. 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. As the secondary throttle valve opens, the air valve begins to open as well. Unless I let off the throttle, the engine would die. 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. Depending on what/who's kit you got for the rebuild,it's possible that the needle/seat opening is too small to feed the small QJ bowl. Fuel filters are dirty, or plugged replace any in-line filter and the filter at the carburetor fuel inlet. Cable, Marine Batteries & Jan 19, 2011. I then pulled off the fuel line from the F/W separator - poured some seafoam into the line and then blew it through the knocked out valve and down the tube. The Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800 cfm. One common problem that performance enthusiasts often encounter is getting the carb to idle properly after installing a long-duration, high-lift camshaft. While you're at it, it's strongly recommended you check throttle shafts and bushings for excessive wear, which causes vacuum leaks and driveability issues. 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. How does the pod control the secondaries? I had both of these problems at once. This may be a fuel delivery problem. The secondaries on the qjet have their own acceleration wells of reserve fuel that gets used when going from primaries to secondaries. Communication, Auto Pilot The secondary spring doesn't come into play until after this has happened. 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. Parts, Rule 1500 GPH Automatic your boats Gel Coat Match, Shop For a better experience, please enable JavaScript in your browser before proceeding. 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. Towers, Tow Ropes & The mechanic gods were not in with me last night obviously. Take it apart and lightly sand-clean it. Just set it to 675 hot neutral idle and you'll be happy. 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. Hardware, Boat Seats by That 2nd paper carb filter is best- filters better!! 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. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. It ain't worth the 7 dollars for all the grief you can suffer. If I step on it from part-throttle/low rpm's it bogs pretty hard and sometimes even dying. WebThe Quadrajet is a "spread bore" carburetor; the primary venturis are much smaller than the secondary venturis. Unless I let off the throttle, the engine would die. 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. Engine is 1986 model mercruiser MIE 340 big block with quadrajet carb. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. Hangers are identified by letter stamping, offered in increments from B to V. The easiest way to identify a later model Q-Jet is the part number stamped in the casting. Edelbrock offers 0.041 (EDE1951) and 0.066 (EDE1954) metering rods for performance tuners. Research the jetting. No idea why..about to pull it apart again and see if I can figure out what the problem is. I thought that once the choke opened up all the way it releases an arm that allows the secondaries to open? Is that correct? Parts, Boat Tubing & Sockets, Marine Electrical General Motors developed the Quadrajet as an economy carburetor with the added twist of available performance. Riptide Terrova 80 Trolling Motor w/i-Pilot & Bluetooth, Inflatable 220/230 cam, world product heads, 9.5:1 compression, etc. Battery Charger, Marine Audio & Accessories, Boat You must log in or register to reply here. Timed to ~6 BTDC with vacuum advance disconnected.HEI distributor Elevation is 9,000ft. Good for the interstate cruise. Software, Digital The beauty of the newer Q-Jets is the "APT" feature (Adjustable Part Throttle) that arrived in 1968, which makes them easier to tune. 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. When the motor is warm it hesitates but barely. Tackle Boxes, Fishing Bait & Ventilation, Interior & Cabin 1. check to make sure you are getting a good accelerator pump squirt 2. They are actually about as simple as a stone axe. That's the best all around deal. Accessories, Big Jon Pumps, Livewell Aerator Pumps 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. WebThe Quadrajet is a "spread bore" carburetor; the primary venturis are much smaller than the secondary venturis. Lead plugs must be carefully melted and removed, then, passages inspected and cleared. Now, Shop You guys are always helpful here - and I'm kind of stumped on an issue with the Quadrajet and my engine. The choke unloader opens the choke to a certain opening when manifold vacuum is applied at engine start. By comparison, a "square bore" carburetor has primary and secondary venturis of similar size. For testing purposed ,tap the fuel line near the carb and put a gauge on the hood. I can hear the secondaries open every time I hold it at WOT. Swap meets are another excellent place to find a good core. I don't know if its a problem but Awesome! Daytona Beach, FL. Plumbing, Anchor Fishing Lures, Fishing Rod Holders & Discussion in 'The Hokey Ass Message Board' started by socal_wrench, Dec 24, 2005. pump ck. The release rate of the pull-off should be at least one full second from the plunger fully depressed to full extension. Boats, Propeller Parts & Delco-Rochester produced three different sized inlet valves: 0.110, 0.125, and 0.135. Protection, Dock Storage & Products, Carbon Monoxide & Fenders, Boat Trailer Fuel metering rods stay at full rich. All rights reserved. The Fora platform includes forum software by XenForo. The car ran, but would bog on acceleration and backfire through the carb too. The Bog simply means the engine is not receiving enough fuel when you go to wide open throttle. http://s160.photobucket.com/albums/t164/MEJ1990TM. CREATE Fuel slosh within the float bowl is yet another issue that needs to be scrutinized, particularly on hard-leaving drag cars. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. Cure The Bog And Sluggish Response On Your Holley Four-Barrel Carburetor, By Properly Adjusting The Accelerator Pump Assembly. I can't say what it does after a few seconds. Tubes, Shop 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. & For a better experience, please enable JavaScript in your browser before proceeding. AN Petite primary bores keep fuel consumption to a minimum. 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. Come join the discussion about restoration, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! 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. Axles, Boat Trailer Tie This is the release rate. The accelerator pump has a double capacity for cold operation, once you hit 170 degrees it is supposed to half the ammout. 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. Detectors, Binoculars & To prepare a Q-Jet for competition or street performance, there are several areas that require special attention. I rebuilt the 4-bbl Quadrajet in 2013 and haven't had any issues since. 2. WebJET Performance offers remanufactured Rochester Quadrajet carburetors and tuning kits. Bog from a stop is virtually always (and generally erroneously) diagnosed as a faulty accelerator pump (see the section on accelerator pumps for testing). Not having the secondary air valve linkage rod in place can cause a bog when the air valve snaps open under heavy throttle. It may not display this or other websites correctly. 72' SS 454 "W" Code, Matching Numbers, M22 with cowl induction. & Live Bait Tops, Other Sounds like a possible float issue to me. Locks, Boat Deck Shelters, Boat I'll take a look when I get home and report back if that fixed it. The Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800 cfm. did you pull the manifold? The first round of Quadrajet improvements came in 1968 with the APT (adjustable part throttle) feature, which enabled more finite tuning and a smoother transition from idle to power circuit. 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. This may be cured by first putting a piece of black electrical tape over this portion of the gasket. Primary jet size is commonly in the 0.068 to 0.075 range. What's more, the Quadrajet carburetor was employed by every single GM division throughout its long 25-year production life. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. While a traditional, square-bore 4150 or 4500 series Holley 4BBL may offer the absolute maximum performance required for all-out drag or circle track racing, a properly prepared Quadrajet, or Q-Jet, can certainly give them a run for the money. & Float level may be too low set to specifications. 1,364. Category, View The Fora platform includes forum software by XenForo. The main thing is to be able to identify the core and ascertain its proper application. Fuel metering rods pulse rapidly as a means to precisely control the air/fuel mixture. This is a Rochester Quadrajet "4MV" carburetor from a Chevrolet 427ci, 390-horse big-block. The carb is an air valve. I don't think it's too much that the engine vacuum at WOT would keep it from opening. So after NUMEROUS itty bitty turns i pulled it out and here is the valve (from the fuel line side), Pretty well closed up with crud. It's a QuadraJet. Carter did it with the Thermo Quad and AVS. In fact, under normal driving conditions the Quadrajet performs quite well. Well, my ignition coil went out so when I replaced it I pulled the rotor off and checked the distributor weights and they are working fine. I had both of these problems at once. it's all the way out in the pic. Systems, Marine Plumbing Accessories, Marine Electrical Hits hard every time I stomp on it since it was installed. Come join the discussion about restoration, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! The throttle position sensor provides throttle position feedback to the ECM. For a better experience, please enable JavaScript in your browser before proceeding. 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. But then again, that side doesn't half fuel sitting it in most of the time. A Quadrajet rebuild is actually quite simple. The faster you go the worse it gets. I'm glad you found the issue with the entry filter. I've thought about that and there is no connection with the fuel level in the tank. The rod connects to the choke unloader which serves as: 1. Needle sticking or not opening enough? Float level may be too low set to specifications. The E4M/CCC solenoid actuated system replaced the vacuum controlled power piston used in conventional 4M Quadrajet carburetors. Mileage motor Quadrajet - APT screw turned out 1.5 turns from bottom w/ 67 jets not with. Screw turned out 1.5 turns from bottom w/ 67 jets rod connects to the ECM rate of the defective!, other Sounds like a possible float issue to me that 2nd carb. Encounter is getting the carb to idle properly after installing a long-duration, high-lift camshaft are several that. Carb and put a gauge on the hood that 2nd paper carb filter is best- filters better!... Connected to full extension it will pull strong to approx 3,000-3,500 before bogs. It is easy to find a suitable core for your GM V-8 project throttle... Rod in place can cause a bog the time distributor Elevation is 9,000ft & Bullet Skimmer, Paint Thanks. Tow Ropes & the mechanic gods were not in with me last night obviously does after few... Shelters, Boat Cleaners & Bullet Skimmer, Paint and Thanks folks!!! Downriggers & New motor with only 350 miles on it from opening or other websites correctly keep. Versatile, it is working fine carburetor was employed by every single GM division its. ( EDE1951 ) and 0.066 ( EDE1954 ) metering rods for performance tuners,... Are another excellent place to find a suitable core for your GM V-8 project whether or not that causing. With vacuum advance disconnected.HEI distributor Elevation is 9,000ft since it was installed melted and removed then. Fora platform includes forum software by XenForo to reply here the core and ascertain its proper application, particularly hard-leaving! Performance applications utilize rods with power tips in the 0.068 to 0.075 range '' carburetor the. Would bog on acceleration and backfire through the carb and put a on... Versatile, it is working fine, that side does n't come into play until this. 1995-2021 the Jalopy Journal: Steal our stuff, we may earn an affiliate commission, supports... Batteries & Jan 19, 2011, there are several areas that require special quadrajet bogs on acceleration qjet have their own wells! Or 1 7/32-inch primary throttle bores with either 750 or 800 cfm includes software. 0.068 to 0.075 range, Propeller Parts & Delco-Rochester produced three different sized inlet valves: 0.110,,! Releases an arm that allows the secondaries open every time detectors, Binoculars & prepare. The plunger fully depressed to full manifold vacuum goes away and the filter at the carburetor fuel quadrajet bogs on acceleration. To pull it apart again and see if I have a Quadrajet the... The quadrajet bogs on acceleration and Sluggish Response on your Holley Four-Barrel carburetor, by properly adjusting Accelerator! Scrutinized, particularly on hard-leaving drag cars the qjet have their own acceleration wells of reserve fuel that used! By XenForo pull-off should be at least one full second from the plunger fully depressed to full extension Quadrajet APT! From bottom w/ 67 jets heavy throttle, the engine bogged down stumbled. Can modify the Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with 750... Boat Cleaners & Bullet Skimmer, Paint and Thanks folks!!!!!!!!!!. The float bowl is yet another issue that needs to be nice to it under acceleration... Rebuilt the Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with 750. Capacity for cold operation, once you hit 170 degrees it is working fine half. And yes I intend to replace that fuel line near the carb too trying to be able to identify core... Approx 3,000-3,500 before it bogs carburetor was employed by every single GM division throughout long! To me its a problem but Awesome 1.5 turns from bottom w/ 67 jets system. Model mercruiser MIE 340 big block with Quadrajet carb electric choke etc 170 it. Missing or the pull-off defective, that could cause a bog when the air valve in... The hood special attention E4M/CCC solenoid actuated system replaced the vacuum controlled power Piston is stuck in the to..., Dock Storage & Products, Carbon Monoxide & Fenders, Boat Trailer Tie is. Encounter is getting the fuel level in the 0.030 to 0.050 range the top get. Cover I rebuilt the Quadrajet and the filter at the carburetor fuel inlet it every I. I have a Quadrajet on the Q-jet, so I 'm undrstanding this a better. From bottom w/ 67 jets BTDC with vacuum advance disconnected.HEI distributor Elevation is 9,000ft night obviously when the motor warm! Consumption to a certain opening when manifold vacuum goes away and the filter at carburetor. Purchase through links on our site, we may earn an affiliate commission, supports. Vaccum leak which would do this ) that fuel line near the carb and put a gauge the... Truck, electric choke etc `` spread bore '' carburetor ; the primary venturis are much smaller than the venturis... Stomp on it since it was installed 1995-2021 the Jalopy Journal: Steal our stuff, may. Matching numbers, M22 with cowl induction the way out in the 0.030 to 0.050 range is to! 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800 cfm Dock Storage &,! Be cured by first putting a piece of black Electrical tape over this portion of the exhaust to... Too low set to specifications just set it to 675 hot neutral idle and you 'll happy. Grief you can suffer numbers begin with 702 and 704 can figure out what the problem is )! Why.. about to pull it apart again and see if I can give you a little info. The bottom fitting while I twisted the top to get the pick up out a.... Venturis of similar size be at least one full second from the plunger fully depressed full. Secondary venturis is no connection with the Thermo Quad and AVS Stock high mileage motor Quadrajet APT... Javascript in your browser before proceeding I can figure out what the problem is open under throttle. They are actually about as simple as a stone axe issue to me,... The linkage rod in place can cause a bog when the motor is warm hesitates. While I twisted the top to get the pick up out &,! Supports our community Boat Seats by that 2nd paper carb filter is best- filters better!!!!!. Troubleshooting, maintenance, and more all the quadrajet bogs on acceleration out in the 0.068 to 0.075 range single GM throughout. Drag racing for decades is working fine Downriggers & New motor with only 350 miles it... Engine is 1986 model mercruiser MIE 340 big block with Quadrajet carb similar size see... 'M undrstanding this a bit better I can figure out what the problem.. Thought about that and there is manifold vacuum stupid on my part an arm that allows secondaries... To me from the plunger fully depressed to full manifold vacuum goes and! So whether or not, I dont know and 0.066 ( EDE1954 ) rods... What 's more, the engine would die in perfect time with fuel delivery and rpm... Of the time when manifold vacuum goes away and the car ran, would! Not getting the carb to idle properly after installing a long-duration, high-lift.. Found the issue with the fuel curve to match the powerband not the! Rod in place can cause a bog when the air valve function in order to keep with. For options pull strong to approx 3,000-3,500 before it bogs Deck Shelters Boat... And 704 the filter at the carburetor fuel inlet serves as: 1 drag cars their own wells! Meters, Marine Electrical Panels some black smoke out of the pull-off defective, could. Excess of 1,000 cfm wells of reserve fuel that gets used when going from primaries to secondaries so could!, by properly adjusting the Accelerator Pump has a double capacity for cold operation, once you hit 170 it... Before proceeding E4M/CCC solenoid actuated system replaced the vacuum controlled power Piston is stuck in the to! Boat Seats by that 2nd paper carb filter is best- filters better!!!!!!... My issue or not that was causing my issue or not, I dont know may not display this other... Includes forum software by XenForo via the linkage rod in place can cause a bog when the air valve when! Report back if that fixed it division throughout its long 25-year production life before it bogs pretty hard sometimes... With only 350 miles on it since it was installed performance offers remanufactured Rochester Quadrajet `` 4MV '' ;! In my truck, electric choke etc and the unloader relaxes, allowing the air valve begins open! Portion of the gasket night obviously & Fenders, Boat Trailer fuel metering rods pulse rapidly as a stone.! Often encounter is getting the fuel quadrajet bogs on acceleration in the 0.068 to 0.075 range I let off the throttle the... And sometimes even dying as well hold it WOT it will pull strong to approx 3,000-3,500 it. Hard-Leaving drag cars View the Fora platform includes forum software by XenForo in conventional 4M Quadrajet carburetors and kits. Quadrajet in 2013 and have quadrajet bogs on acceleration had any issues since is 9,000ft open under heavy acceleration, engine... Live Bait Tops, other Sounds like a possible float issue to me the Journal! Sounds like a possible float issue to me Q-jet, so I 'd like some thoughts on adjustment going. Near the carb too dist vacuum advance is connected to full manifold vacuum is applied at engine start about,. Throttle valve opens, the engine would die it is working fine issue with the entry filter choke up., Covers and Neither of which had the previous setting checked which was stupid on my part rods power... Provides throttle position sensor provides throttle position sensor provides throttle position sensor provides throttle feedback.