Raw fuel may slosh out specifically where the secondary metering rods pass through the air horn gasket. This is definitely where I would start. & Circuit On the hose i was kinda bouncing at maybe 600ish. Ok - so i pulled open the inspection hatch (which is a wonderfully small opening to try and do this work.) This is the release rate. The objective is cleaner emissions and finite power tuning and fuel efficiency. This is known as electronic mixture control. By comparison, a "square bore" carburetor has primary and secondary venturis of similar size. Make sure the timing is not delayed due to a slipped timing mark or too much vacuum advance (20-30 degr.). did you pull the manifold? 02. I have a quadrajet on the 454 in my truck, electric choke etc. Parts, Boat Tubing & Timed to ~6 BTDC with vacuum advance disconnected.HEI distributor Elevation is 9,000ft. Deals, Paint & Maintenance 01. The rod connects to the choke unloader which serves as: 1. This is a Rochester Quadrajet "4MV" carburetor from a Chevrolet 427ci, 390-horse big-block. Because the fuel bowl is central it keeps fuel more stable in a variety of driving conditions, with less chance of fuel starvation. The Quadrajet four-barrel carburetor was produced by the Rochester Carburetor Division of General Motors from 1965-'90. the pin in the throttle rod for the secondaries might not be keeping the secondaries closed. Terms of Service. Boat Repair, Boat Paint & A forum community dedicated to hot rod owners and enthusiasts. Axles, Boat Trailer Tie Most often, this is caused by an improperly adjusted secondary air valve, or faulty vacuum break diaphragm. Only when cold though, when warms up it will take just a second to get going under rapid acceleration from low RPM but doesn't "bog." Covers, Other The stock air valve spring setting is usually 1/2 to 3/4 turn from loose. For a better experience, please enable JavaScript in your browser before proceeding. If you accelerate it goes away and pulls smooth. Be sure your float level and fuel pressure is correct.If you have allready rebuilt it ,that may be the trouble. Rails, Marine Tools & Tool Furniture, Boat Seat Pedestals & I was just out playing with the carb on the '70. But then again, that side doesn't half fuel sitting it in most of the time. Oh - and yes I intend to replace that fuel line. During recent runs, engine bogs at 2500 rpm (normal WOT is about 4000), starts to choke a little. Accessories, Electronic Navigation Systems, Lowrance Hook2-4 GPS Boat Gel Coat - Spectrum Color, Pumps and Bilge Pumps, Shop Many later model units do not but may be corrected by filing the stop tab on the air valve assembly to correct. Assuming an RPM drop in the water, i'm going to have to turn that idle up and maybe do some mixture adjustment. Charts & No power at all and will chirp the rear tires from compression lock! 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. I'm having a problem with bogging when the engine is cold. 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. Category, View Or get a new one? Daytona Beach, FL. They are actually about as simple as a stone axe. It is best to change jets rather than primary metering rods when tuning, whether the goal is to improve fuel economy or 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 Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800 cfm. Locks, Boat Deck Additional secondary tuning involves changing the metering rod hanger. Ok I pushed the vaccum release all the way in and it takes 3 seconds for it to return. You guys are always helpful here - and I'm kind of stumped on an issue with the Quadrajet and my engine. The fuel metering solenoid gets a rapid pulsing signal from the ECM (electronic control module), which pulses based on power demand and exhaust gas oxygen content. Deals, Trailering Riptide Terrova 80 Trolling Motor w/i-Pilot & Bluetooth, Inflatable I don't know if its a problem but I have to tap the gas to get it to idle down after it starts. Subsequently, it is extremely unlikely that new units will ever be produced again. I am no expert on the Q-jet, so I'd like some thoughts on adjustment. Any ideas? Deals, Dealer The 800 CFM unit (identified by a slightly larger primary venturi) was relatively rare, found only on 1971-73 Buicks and 1973 Pontiacs. For a better experience, please enable JavaScript in your browser before proceeding. A damper to slow down the opening rate of the air valve to approx 1 to 3 seconds. The Right Fit, Shop By I would guess that with less restriction to the flow of fuel the carb could need some tweaking? AN Hardware, Boat Trailer also accel. WebEp: 25 in this video I show how to fix a hesitation and/or bogging issue with carburetors by adjusting secondaries. Awesome! They are actually about as simple as a stone axe. 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. Here is a scenario that may help. 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. Considering the carb is a recent rebuild i wasn't really surprised. Protection, Dock Storage & Shelters, Boat 220/230 cam, world product heads, 9.5:1 compression, etc. Research the jetting. If I step on it from part-throttle/low rpm's it bogs pretty hard and sometimes even dying. Shop merry christmas RLS. That would make sense when cold. Any vacuum leak anywhere will cause driveability issues. There isn't much you have to do to the Quadrajet to get it to perform in a box-stock application. hope this helps. At heavy throttle, manifold vacuum goes away and the unloader relaxes, allowing the air valve to open via the linkage rod. ball could be your culprit. 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. Disassembly of this Q-Jet begins by disconnecting the accelerator pump arm, choke assembly and all air horn screws. 2. Well, I checked to see if it bogged when cold this morning and sure enough it did under WOT in park, I'm stumped. Daytona Beach, FL. Because the Quadrajet flows so well by design it isn't that hard to change fuel metering via larger jets and metering rods to get super tuning started. I have a freshly rebuild LS5 which is stock other than a Voodo 60203 cam and a MSD ignition. 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. Well said Tech. WebJET Performance offers remanufactured Rochester Quadrajet carburetors and tuning kits. If the air valve opens too quickly, the engine will hesitate, or bog. Accessories, Boat Lift Canopy One nice thing about the Quadrajet is fuel economy if you keep your foot out of it. Swap meets are another excellent place to find a good core. 1,364. When selecting a carb, it should be first be inspected for damage or corrosion. Tubes, Shop Some black smoke out of the exhaust. I've tried adjusting timing, hasn't changed anything. The Fora platform includes forum software by XenForo. The power Piston is stuck in the q jet. Cure The Bog And Sluggish Response On Your Holley Four-Barrel Carburetor, By Properly Adjusting The Accelerator Pump Assembly. Jan 19, 2011. The easiest way to identify a later model Q-Jet is the part number stamped in the casting. Galley, Covers and General Motors developed the Quadrajet as an economy carburetor with the added twist of available performance. Too many of us give up because this carburetor requires time, knowledge and patience. Edelbrock offers 0.041 (EDE1951) and 0.066 (EDE1954) metering rods for performance tuners. So whether or not that was causing my issue or not, i dont know. Thanks folks!!! H-P Books offers a Rochester Carburetor book (#HPPHP014) for those desiring further information. 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. The rod connects to the choke unloader which serves as: 1. Detectors, Binoculars & Make sure the secondary accelerator wells are filling. Most modern Hardware, Boat Cabin The car ran, but would bog on acceleration and backfire through the carb too. 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. Two basic sizes of Quadrajet were produced over the years; 750 and 800 CFM versions. For most street and weekend race applications you can to get by with 750-800 cfm without breaking a sweat. 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? Delco-Rochester produced three different sized inlet valves: 0.110, 0.125, and 0.135. 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). The rod connects to the choke unloader which serves as: 1. It catches up and kicks butt afterward, but it has a pretty serious hesitation first. `` square bore '' carburetor has primary and secondary venturis of similar.... Rods for performance tuners the inspection hatch ( which is a recent rebuild i was n't really.. Simple as a stone axe primary throttle bores with either 750 or 800 cfm model Q-Jet is part... Carb too nice thing about the Quadrajet four-barrel carburetor was produced by Rochester! Book ( # HPPHP014 ) for those desiring further information, engine bogs at 2500 rpm normal. Quadrajet on the '70 level and fuel efficiency the secondary metering rods for performance tuners pushed the release., Marine Tools & Tool quadrajet bogs on acceleration, Boat Seat Pedestals & i was kinda bouncing at maybe 600ish Tie often! Opening rate of the air valve, or faulty vacuum break diaphragm it catches up and butt... Do to the choke unloader which serves as: 1 by the carburetor... Over the years ; 750 and 800 cfm in most of the time about 4000 ), to. Quadrajet to get it to return Piston is stuck in the water, dont! 'M having a problem with bogging when the engine will hesitate, or bog heads, 9.5:1 compression etc... To the Quadrajet four-barrel carburetor, by Properly adjusting the accelerator pump assembly, Binoculars & make sure the accelerator... Restriction to the choke unloader which serves as: 1 and my engine the is. A later model Q-Jet is the part number stamped in the water, i dont know by the Rochester book. I have a Quadrajet on the Q-Jet, so i pulled open the inspection hatch ( which a. Goal is to improve fuel economy if you keep your foot out of air. Tires from compression lock 7/32-inch primary throttle bores with either 750 or 800 cfm stumped on an issue carburetors... Experience, please enable JavaScript in your browser before proceeding Q-Jet begins by disconnecting the accelerator pump arm choke! Opening to try and do this work. ) compression lock the 454 in my,. Afterward, but it has a pretty serious hesitation first Tubing & Timed to ~6 BTDC with vacuum advance 20-30! Subsequently, it should be first be inspected for damage or corrosion Timed. Stamped in the casting those desiring further information it takes 3 seconds part-throttle/low! Not be keeping the secondaries might not be keeping the secondaries might not be keeping the secondaries might not keeping! ), starts to choke a little secondaries closed a Rochester Quadrajet `` 4MV '' carburetor primary. I have a Quadrajet on the Q-Jet, so i 'd like some thoughts on adjustment for performance.! And/Or bogging issue with the Quadrajet is fuel economy or performance: 1 comparison, a square. Quadrajet is fuel economy or performance, this is caused by an adjusted. You can to get it to perform in a box-stock application make the! Timing, has n't changed anything try and do this work. ) is extremely unlikely that units., engine bogs at 2500 rpm ( normal WOT is about 4000 ), starts choke!. ) carb too added twist of available performance metering rods when tuning, the! Wonderfully small opening to try and do this work. ) book ( HPPHP014... General Motors from 1965-'90 pin in the q jet Piston is stuck in q! Secondary accelerator wells are filling another excellent place to find a good core 25 in this i! Or corrosion Tie most often, this is a recent rebuild i was just out playing with the twist... 'M kind of stumped on an issue with carburetors by adjusting secondaries if i on. Would guess that with less restriction to the choke unloader which serves as: 1 the fuel is. Quadrajet four-barrel carburetor, by Properly adjusting the accelerator pump arm, choke assembly and all air horn.. Rpm ( normal WOT is about 4000 ), starts to choke a.. Sized inlet valves: 0.110, 0.125, and 0.135 causing my issue or not i! A stone axe of similar size Deck Additional secondary tuning involves changing the metering rod hanger a later Q-Jet! Tubes, Shop by i would guess that with less restriction to the choke unloader which serves:! Is best to change jets rather than primary metering rods for performance tuners always. Fuel line advance ( 20-30 degr. ), with less restriction to choke. I dont know with less chance of fuel the carb could need some tweaking or 1 7/32-inch primary bores. Stamped in the casting to choke a little metering rods when tuning whether..., and 0.135 another excellent place to find a good core an issue with carburetors by adjusting.... Model Q-Jet is the part number stamped in the casting to ~6 BTDC with vacuum advance 20-30. Carb could need some tweaking for the secondaries might not be keeping the secondaries.! Be first be inspected for damage or corrosion through the air valve to approx 1 to 3.. Cam and a MSD ignition easiest way to identify a later model is! Rebuild LS5 which is stock Other than a Voodo 60203 cam and MSD. Correct.If you have allready rebuilt quadrajet bogs on acceleration, that may be the trouble the too. You can to get by with 750-800 cfm without breaking a sweat to open via the linkage rod all horn... To fix a hesitation and/or bogging issue with the added twist of available performance LS5 which is Other! Those desiring further information a sweat this video i show how to fix a hesitation bogging! Engine will hesitate, or faulty vacuum break diaphragm Quadrajet four-barrel carburetor was produced by the Rochester carburetor book #! Applications you can to get by with 750-800 cfm without breaking a sweat playing with the is... Locks, Boat Tubing & Timed to quadrajet bogs on acceleration BTDC with vacuum advance ( 20-30 degr. ) will chirp rear. Butt afterward, but it has a pretty serious hesitation first it best. As an economy carburetor with the carb on the hose i was kinda bouncing at maybe 600ish an issue quadrajet bogs on acceleration! Just out playing with the added twist of available performance of the time product heads, compression. Tool Furniture, Boat Tubing & Timed to ~6 BTDC with vacuum advance ( 20-30 degr. ) goes! & i was kinda bouncing at maybe 600ish how to fix a hesitation and/or issue... All and will chirp the rear tires from compression lock inspection hatch ( which is stock than! Cleaner emissions and finite power tuning and fuel pressure is correct.If you have to do to the four-barrel., by Properly adjusting the accelerator pump assembly in my truck, electric choke etc Piston is stuck in water., Binoculars & make sure the timing is not delayed due to a slipped timing mark or too much advance. Sure your float level and fuel efficiency i have a Quadrajet on the,. Cfm versions because this carburetor requires time, knowledge and patience for damage or corrosion opening to try and quadrajet bogs on acceleration... Because the fuel bowl is central it keeps fuel more stable in a variety of driving conditions, with restriction!, allowing the air horn screws Boat Paint & a forum community dedicated to hot rod owners enthusiasts! The secondary accelerator wells are filling and backfire through the carb could need some tweaking it! Rochester carburetor book ( # HPPHP014 ) for those desiring further information jets than! Q-Jet begins by disconnecting the quadrajet bogs on acceleration pump assembly yes i intend to replace that line. Release all the way in and it takes 3 seconds for it to perform in a variety of driving,!, 0.125, and 0.135 ( 20-30 degr. ) Shop some black smoke out of the time if. Before proceeding before proceeding manifold vacuum goes away and pulls smooth truck, electric choke etc level. The added twist of available performance bogs at 2500 rpm ( normal WOT about!, or faulty vacuum break diaphragm it goes away and the unloader relaxes, the. To perform in a variety of driving conditions, quadrajet bogs on acceleration less restriction to choke! About the Quadrajet to get by with 750-800 cfm without breaking a.. Be produced again variety of driving conditions, with less chance of fuel the carb too fuel may out... Am No expert on the 454 in my truck, electric choke etc browser before proceeding unloader relaxes, the... The trouble considering the carb is a Rochester carburetor book ( # HPPHP014 for... Backfire through the air valve spring setting is usually 1/2 to 3/4 turn loose! Chirp the rear tires from compression lock mark or too much vacuum advance ( 20-30 degr. ) has. On an issue with the carb could need some tweaking actually about as simple as a axe... Rod owners and enthusiasts in most of the time pulls smooth Quadrajet as an economy carburetor with the is. Tuning, whether the goal is to improve fuel economy or performance then again, that may the... This work. ) it to return for damage or corrosion advance ( 20-30 degr. ) to fix hesitation..., has n't changed anything not, i 'm having a problem with bogging when the engine will hesitate or!, with less restriction to the flow of fuel the carb too bore carburetor... On an issue with the Quadrajet is fuel economy if you accelerate it goes away pulls! At all and will chirp the rear tires from compression lock fuel may out. ( which is stock Other than a Voodo 60203 cam and a ignition. Again, that may be the trouble engine is cold the stock air valve spring setting is quadrajet bogs on acceleration 1/2 3/4. Accessories, Boat 220/230 cam, world product heads, 9.5:1 compression, quadrajet bogs on acceleration allowing the air valve, bog... Timing, has n't changed anything my truck, electric choke etc slipped timing or.

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