JavaScript is disabled. Communication, Auto Pilot Terminal Platforms, Slide Terms of Service. The Q jet is a fantastic carb. Any vacuum leak anywhere will cause driveability issues. During recent runs, engine bogs at 2500 rpm (normal WOT is about 4000), starts to choke a little. 1. check to make sure you are getting a good accelerator pump squirt 2. Following all of these procedures and doing a thorough rebuild will certainly wake up any Quadrajet. If the secondaries open too fast there is not enough vacuum signal to get the fuel flowing and you get bog. I checked the lock bar out and it is working fine. did you pull the manifold? I'm trying to remember what things look like when the engine is running and I'm 99% sure that the pod you are refering to is pulled in all the way. This thing runs great, starts every time and idles nice. The secondary air valves, located in the air horn, allow a smooth transition into the secondaries via manifold vacuum at wide-open throttle. Non computer controlled (1986). The Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800 cfm. Guide, Boat Maintenance, Pumps and ACCOUNT, Find Here is a scenario that may help. I'm not Mike but I'm pretty up on Quadrajets and have worked with them quite a bit. On on end of the secondary air door shaft, on the underside, is a small clamp screw. Needle sticking or not opening enough? Towers, Tow Ropes & you floor it, it pops through the carb and falls over. 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. And fuel pump pressure. Axles, Boat Trailer Tie The Fora platform includes forum software by XenForo. Fuel filters new? & no vac, engine off, that's right. Not having the secondary air valve linkage rod in place can cause a bog when the air valve snaps open under heavy throttle. Is that correct? Ok I pushed the vaccum release all the way in and it takes 3 seconds for it to return. By comparison, a "square bore" carburetor has primary and secondary venturis of similar size. Caulking, Marine Engine I don't know if its a problem but & Rings, Prop Nut Kits & I rebuilt the 4-bbl Quadrajet in 2013 and haven't had any issues since. During recent runs, engine bogs at 2500 rpm (normal WOT is about 4000), starts to choke a little. Kits, Seadog Stainless Steel Cup For most street and weekend race applications you can to get by with 750-800 cfm without breaking a sweat. Hardware, Boat Cabin Before tearing into the carb first check some easy things like for a vacuum leak. Here is a scenario that may help. JavaScript is disabled. 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. Thanks! 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? 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. Two basic sizes of Quadrajet were produced over the years; 750 and 800 CFM versions. Or get a new one? 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. Timed to ~6 BTDC with vacuum advance disconnected.HEI distributor Elevation is 9,000ft. The Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800 cfm. There is no mistaking that quadrajet sound when you get into it, so I don't think that its keeping them from opening. Biminis, RV & Trailer 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. Anchor Box Anchors, Fishing Rod & Reel Another possibility, and it is real. I have a qradrajet carb on a 350 chevy. They are actually about as simple as a stone axe. I was just out playing with the carb on the '70. Different pull-offs have different release rates. Bullet Skimmer, Paint and The Fora platform includes forum software by XenForo. I like the quadrajet.I even like the electronic ones.They are easy to set up actually( because I have done so many). Pull the top off the carburetor and check to see if the secondary accelerator tubes are both still in place. At heavy throttle, manifold vacuum goes away and the unloader relaxes, allowing the air valve to open via the linkage rod. Instruments, VHF Radios & Protection, Ladders, Steps, & Jan 19, 2011. 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. ball could be your culprit. Two basic sizes of Quadrajet were produced over the years; 750 and 800 CFM versions. Small-blocks through 350 ci are happiest with 750 cfm. All employ air valve transition into the secondaries. Vinyl, Floating Boat It may not display this or other websites correctly. Along with a good timing curve, is the choke vacuum pull-off set-up correctly or hooked up. The Quadrajet four-barrel carburetor was produced by the Rochester Carburetor Division of General Motors from 1965-'90. 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. 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. Well said Tech. It's a good idea to isolate the primaries when tuning anyway. Come join the discussion about restoration, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! I have a freshly rebuild LS5 which is stock other than a Voodo 60203 cam and a MSD ignition. For a better experience, please enable JavaScript in your browser before proceeding. Carter did it with the Thermo Quad and AVS. An O2 sensor in the exhaust monitors exhaust oxygen content. The Quadrajet is the best street carb made, they`re pretty much all I use as when they`re right they`re hard to beat. Forums, Find Wow, great pics. The secondaries on the qjet have their own acceleration wells of reserve fuel that gets used when going from primaries to secondaries. Hardware, Marine Just set it to 675 hot neutral idle and you'll be happy. And this has been proven in drag racing for decades. Did you know Ford ran the Quadrajet on its 1970-'71 429ci big-blocks. We decided to visit Ted's Carburetor Service in Lancaster, California, north of Los Angeles, which showed us how to properly tune GM's spreadbore carburetor. They are notorious for leaking since they are only press-fit from the factory. You'll want to find a newer, more refined core, which is typically from the 1970s and early 1980s. 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. WebJET Performance offers remanufactured Rochester Quadrajet carburetors and tuning kits. & Dock, Anchor Chains & This is the release rate. Tubes, Shop 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. & Live Bait But, I'm sure it wasn't helping the situation. Accelerates smoothly and with no problem. The primaries must open considerably to reach the "tip in" point. 1. check to make sure you are getting a good accelerator pump squirt 2. I have a quadrajet on the 454 in my truck, electric choke etc. Furniture, Boat Seat Pedestals & 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. You guys are always helpful here - and I'm kind of stumped on an issue with the Quadrajet and my engine. Seats, Pontoon Boat Seats & That was in park as it's an automatic(th350.). Fishing Lures, Fishing Rod Holders & Daytona Beach, FL. Trolling Motors, Shop Covers, Boat Seat The Fora platform includes forum software by XenForo. Systems, Lowrance Hook2-4 GPS When I say it bogs, it really bogs! I'm glad you found the issue with the entry filter. Most modern thanks NH! Two "buttons" on front of carb are probably caps covering your primary idle adj. Check it when cold and hot. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. That 2nd paper carb filter is best- filters better!! Twisted, are you talking under this bit here? Assuming an RPM drop in the water, i'm going to have to turn that idle up and maybe do some mixture adjustment. Engine is 1986 model mercruiser MIE 340 big block with quadrajet carb. Detectors, Binoculars & The float assembly is removed next. However, you're not going to need that much flow for great street/strip performance. 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. Despite the Quadrajet's reputation for frustrating tunability, it is a great performer when it is properly assembled and tuned. Quadrajet High Speed Lack of Power Lack of power is often caused by electrical, or engine wear. Because the Quadrajet is a vacuum controlled spreadbore carburetor, it can be tricky to tune. screws. Financing, Iboats Easy to set up actually ( because i have a qradrajet carb on 350! 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Like the quadrajet.I even like the electronic ones.They are easy to set up actually because. An O2 sensor in the exhaust monitors exhaust oxygen content or other websites correctly this thing runs great starts! Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800....