I had both of these problems at once. That also could have contributed to the problem yet was doing its job!! Fuel metering rods pulse rapidly as a means to precisely control the air/fuel mixture. Be sure your float level and fuel pressure is correct.If you have allready rebuilt it ,that may be the trouble. Not having the secondary air valve linkage rod in place can cause a bog when the air valve snaps open under heavy throttle. During recent runs, engine bogs at 2500 rpm (normal WOT is about 4000), starts to choke a little. Remanufactured stock replacement and high-performance units are still readily available from a variety of sources, including JET Performance Products (JET). Fuel metering became electronically controlled in 1980. Come join the discussion about restorations, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! Test this pump for fuction at the sensor and pump. 04. Login, Boats Starters, Marine Solar Power CREATE Let's say about 300 horsepower to help give you can idea. As the secondary throttle valve opens, the air valve begins to open as well. Starving for fuel top end. 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. Pull the top off the carburetor and check to see if the secondary accelerator tubes are both still in place. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. 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. The Fora platform includes forum software by XenForo. It's a QuadraJet. There are still Quadrajets in their factory packaging out there. Considering the carb is a recent rebuild i wasn't really surprised. An O2 sensor in the exhaust monitors exhaust oxygen content. The pull-off is connected by a linkage rod. Jan 19, 2011. Cure The Bog And Sluggish Response On Your Holley Four-Barrel Carburetor, By Properly Adjusting The Accelerator Pump Assembly. Pump shot may be increased or decreased by altering its travel, accomplished by re-locating the pump linkage to the opposite hole in the pump actuation lever. The choke unloader opens the choke to a certain opening when manifold vacuum is applied at engine start. I rebuilt the 4-bbl Quadrajet in 2013 and haven't had any issues since. Accessories, Electronic Navigation Motors, Fishing Downriggers & Boats, Propeller Parts & This design is not unique to the Quadrajet. Float level may be too low set to specifications. Make sure the timing is not delayed due to a slipped timing mark or too much vacuum advance (20-30 degr.). 1160 hours on engine. The trick is finding a good core you can build from. Terminal Check the fuel tank vent and the anti-syphon check valve. Shop Cure The Bog And Sluggish Response On Your Holley Four-Barrel Carburetor, By Properly Adjusting The Accelerator Pump Assembly. The hole in the restriction should be about .018-.020. If the choke could be the problem since it's only when it's cold how would I check that? I know the pod that you are talking about but that is it. It needs to be loosened, and the air door spring tension adjusted. It has been proven you can modify the Quadrajet to flow in excess of 1,000 cfm. By comparison, a "square bore" carburetor has primary and secondary venturis of similar size. Maybe the choke is open too far? Cure The Bog And Sluggish Response On Your Holley Four-Barrel Carburetor, By Properly Adjusting The Accelerator Pump Assembly. ACCOUNT, Find Unless I let off the throttle, the engine would die. Screws, Boat Handles, Pulls, Thanks folks!!! Jacks, Boat Trailer Brakes & http://www.73-87.com/7387garage/drivetrain/myqjet.htm. Boat Gel Coat - Spectrum Color, Pumps and I have a quadrajet on the 454 in my truck, electric choke etc. Engine is 1986 model mercruiser MIE 340 big block with quadrajet carb. 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. That is, until my last outing Under heavy acceleration, the engine bogged down and stumbled. The secondary air valves, located in the air horn, allow a smooth transition into the secondaries via manifold vacuum at wide-open throttle. Another possibility, and it is real. And, here is what i see pretty ugly - but most of what was there wiped away - just crud built up from washes/water it appears. Jan 19, 2011. For testing purposed ,tap the fuel line near the carb and put a gauge on the hood. 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. 1. check to make sure you are getting a good accelerator pump squirt 2. 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. Biminis, Paint and Make sure the secondary accelerator wells are filling. The easiest way to identify a later model Q-Jet is the part number stamped in the casting. Following all of these procedures and doing a thorough rebuild will certainly wake up any Quadrajet. And the clouds parted and angels sang out in chorus - WOT was reached continually. Deals, Electronics The Mercruiser 5.0LX in my 1989 Arriva 2050 KE has been running well for the last couple of years. 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. The boat is going out early Saturday morning, so if it was just the valve and all works, then sweet. 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. Dollies, SportsStuff Great Big I don't know if its a problem but Test the solenoilds, the choke has one on the throttle and secondaries blades. Timed to ~6 BTDC with vacuum advance disconnected.HEI distributor Elevation is 9,000ft. Forums, Find It controls the air door, if the air door opens too quickly it will hesitate. They were touching the bottom of the air cleaner, and apparently they were only arcing under acceleration under load. If I step on it from part-throttle/low rpm's it bogs pretty hard and sometimes even dying. Instruments, VHF Radios & thanks NH! 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. I did some looking on this site and others and i've done a lot of youtube watching on these carbs. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. Detectors, Binoculars & When it bogs its violent enough that I let off. I have a quadrajet on the 454 in my truck, electric choke etc. 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. Secondly is that at cruising speeds, 50-55 MPH it has a slight surge. to fix the sticking lifter did you replace it? This thing runs great, starts every time and idles nice. Biminis, View Bilge Pumps, Shop I have a quadrajet on the 454 in my truck, electric choke etc. You are using an out of date browser. Daytona Beach, FL. So I don't think the stumble like John described would be caused by a loose air valve spring. Cable, Marine Batteries & The car ran, but would bog on acceleration and backfire through the carb too. See if all is same then? I don't think your problem is the carburator. The idle is set at 900rpm without vaccume advance plugged in. Oars, Wakeboard, Wakesurf & 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. Additionally, as the secondary air valve opens, the secondary metering rods are raised out of the secondary metering orifices. Two basic sizes of Quadrajet were produced over the years; 750 and 800 CFM versions. Assuming an RPM drop in the water, i'm going to have to turn that idle up and maybe do some mixture adjustment. Usually the symptoms that you have described are a ignition issue. Breakers, Power Packs & Jump Neither of which had the previous setting checked which was stupid on my part. screws. Check eBay, Craigslist and Racing Junk websites for options. 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. Marble, Engine Protection, Ladders, Steps, & Accessories, Big Jon Riptide Terrova 80 Trolling Motor w/i-Pilot & Bluetooth, Inflatable The rod connects to the choke unloader which serves as: 1. Fishing Lures, Fishing Rod Holders & Secondary fuel metering can therefore be altered by changing these rods, easily performed without having to disassemble the carb. Parts, Inflatable Unless I let off the throttle, the engine would die. Distribution, ProMariner ProNautic 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? When depressing the butterfly it resists a little bit. Tops, Bimini Top I wouldn't sweat that idle speed change. The Q-Jet has small primaries for normal driving and large mechanical air valve-assisted secondaries for wide-open throttle performance and acceleration. A misadjusted secondary air valve spring can cause bogging but that's really only when you floor it. The downside to older Quadrajet cores is abuse and core shift. Smoke Racks, Fish Finders, Sounders Authentication and pre-purchase inspection service still available. JavaScript is disabled. I then took out the fuel-filter at the carb, and for all intents and purposes it looked brand new. Hardware, Boat Cabin Deals, Boat Seats Biminis, RV & Trailer By comparison, a "square bore" carburetor has primary and secondary venturis of similar size. Handles, Pulls, Thanks folks!!!!!!!... Create let 's say about 300 horsepower to help give you can build from will certainly wake up any.. Are filling Binoculars & when it bogs pretty hard and sometimes even dying 800 cfm versions and maybe do mixture., Ontario, M5V 2H1, Canada classifieds, troubleshooting, maintenance, and the air cleaner and., 50-55 mph it has been running well for the last couple of years but. Door, if the air door opens too quickly it will pull strong to approx 3,000-3,500 before it pretty. Rod in place under heavy acceleration, the engine bogged down and stumbled, Properly... Pulse rapidly as a means to precisely control the air/fuel mixture you build... Had the previous setting checked which was stupid on my part during recent runs, engine at! 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