1160 hours on engine. Protection, Ladders, Steps, & Before tearing into the carb first check some easy things like for a vacuum leak. I did some looking on this site and others and i've done a lot of youtube watching on these carbs. I rebuilt the Quadrajet and the car starts and runs very smooth. Passage integrity can be ascertained by blowing WD-40 or carburetor cleaner through these passages and observing fluid flow. Deals, Camping & RV Follow the carb kit instructions and take lots of pictures during disassembly. This thing runs great, starts every time and idles nice. i like the anti-siphon valve check - i'll add that to my list while I'm in there (easy to check while checking the pick-up tube). Motors, Fishing Downriggers & 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. 01. Fuel filters are dirty, or plugged replace any in-line filter and the filter at the carburetor fuel inlet. you floor it, it pops through the carb and falls over. The rod connects to the choke unloader which serves as: 1. The Fora platform includes forum software by XenForo. did you pull the manifold? Different pull-offs have different release rates. 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. Come join the discussion about restorations, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! At heavy throttle, manifold vacuum goes away and the unloader relaxes, allowing the air valve to open via the linkage rod. Check eBay, Craigslist and Racing Junk websites for options. Daytona Beach, FL. Two basic sizes of Quadrajet were produced over the years; 750 and 800 CFM versions. Some black smoke out of the exhaust. it's all the way out in the pic. Handles, Life Jackets & hope this helps. your boats Gel Coat Match, Shop That also could have contributed to the problem yet was doing its job!! 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. Blowing through the check valve side did open and allow air through. WebJET Performance offers remanufactured Rochester Quadrajet carburetors and tuning kits. Wells, Toilet & Waste was strange. Deals, Dealer 1,364. The thing that is puzzling me is that it does not do it every time. My 89 5.7 qjet changed idle quite a bit. 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. & Rings, Prop Nut Kits & The secondary spring doesn't come into play until after this has happened. Blocks, Marine General Motors developed the Quadrajet as an economy carburetor with the added twist of available performance. Make sure the timing is not delayed due to a slipped timing mark or too much vacuum advance (20-30 degr.). There are still Quadrajets in their factory packaging out there. New motor with only 350 miles on it so I'm trying to be nice to it. The Mercruiser 5.0LX in my 1989 Arriva 2050 KE has been running well for the last couple of years. 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. The Quadrajet has mechanical secondaries, which open promptly when you mash the gas. 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." 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. LOL. JavaScript is disabled. Did you know Ford ran the Quadrajet on its 1970-'71 429ci big-blocks. "Detroit hasn't felt any real pride since George Bush went to Japan and vomited on their auto executives, I tell you whut". Fuel filters new? No idea why..about to pull it apart again and see if I can figure out what the problem is. I am no expert on the Q-jet, so I'd like some thoughts on adjustment. Just doesn't have immediate throttle response when going WOT from low RPM's. As the secondary throttle valve opens, the air valve begins to open as well. 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. Deals, Pumps & Plumbing There's a allen-head set screw on the passenger side which you need to loosen, the adjustment screw is above it. The rod connects to the choke unloader which serves as: 1. Fuel slosh within the float bowl is yet another issue that needs to be scrutinized, particularly on hard-leaving drag cars. Software, Digital A damper to slow down the opening rate of the air valve to approx 1 to 3 seconds. 9000 feet is pretty high. Deals, Electrical 2. For most street and weekend race applications you can to get by with 750-800 cfm without breaking a sweat. Another possibility, and it is real. It has been proven you can modify the Quadrajet to flow in excess of 1,000 cfm. The feedback Quadrajet has two connectors; a three-pin connector for the throttle position sensor and a two-pin connector for the fuel metering solenoid. For a better experience, please enable JavaScript in your browser before proceeding. Authentication and pre-purchase inspection service still available. 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. & Live Bait Is that correct? JavaScript is disabled. REALLY wanting to clean it somehow, i cleaned out the old anti-siphon, knocked out the check valve and re-installed it in the fitting and re-attached the fuel line. Another method of rectifying this is by drilling a small hole in each primary throttle blade to lean the engine a bit at idle. The Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800 cfm. SPECIAL NOTE: Edelbrock actually procured the manufacturing rights and molds from Delco-Rochester for the Quadrajet some years back, and had Magnetti-Marelli reproduce the carb for a period, however, the project was not profitable and they were forced to write the project off for tax purposes and destroy the original molds. The downside to older Quadrajet cores is abuse and core shift. The Q-Jet has small primaries for normal driving and large mechanical air valve-assisted secondaries for wide-open throttle performance and acceleration. Assuming an RPM drop in the water, i'm going to have to turn that idle up and maybe do some mixture adjustment. That 2nd paper carb filter is best- filters better!! Jan 19, 2011. It's a QuadraJet. Communication, Auto Pilot Yours should be around 2 seconds. Dollies, SportsStuff Great Big The power Piston is stuck in the q jet. The secondaries on the qjet have their own acceleration wells of reserve fuel that gets used when going from primaries to secondaries. Trolling Motors, Shop Make sure the timing is not delayed due to a slipped timing mark or too much vacuum advance (20-30 degr.). Drink Holders, http://www.marinepartssource.com/new0Fuel%20Filter, http://discountmarinesource.com/p-52847-sierra-in-line-fuel-filter-7855.aspx. WebThe Quadrajet is a "spread bore" carburetor; the primary venturis are much smaller than the secondary venturis. The air valve may be adjusted by first backing off the Allen head lock screw (located on right side of the air horn) and then turning the adjusting screw clockwise to tighten the tension, or counterclockwise to loosen using a small screwdriver. The pull-off is connected by a linkage rod. 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. Another possibility, and it is real. http://www.73-87.com/7387garage/drivetrain/myqjet.htm. WebThe Quadrajet is a "spread bore" carburetor; the primary venturis are much smaller than the secondary venturis. & Circuit Thanks! Here is a scenario that may help. See if all is same then? That was in park as it's an automatic(th350.). I thought that was it? there are other things inside a Q jet that could cause it like bent primary rod hanger, dirt in the wrong place, etc. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. Small-blocks through 350 ci are happiest with 750 cfm. So i couldn't hold the bottom fitting while i twisted the top to get the pick up out. But, I'm sure it wasn't helping the situation. Test this pump for fuction at the sensor and pump. The thing is, the motor was not bogging before and the only thing that has changed since is the timing and the APT screw along with a lifter sticking. To prepare a Q-Jet for competition or street performance, there are several areas that require special attention. 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. I then took out the fuel-filter at the carb, and for all intents and purposes it looked brand new. Fenders, Boat Trailer Additionally, as the secondary air valve opens, the secondary metering rods are raised out of the secondary metering orifices. 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. Newer castings begin with 170. it keeps the carb closed on the secondary side when cold. 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. The late John Lingenfelter, a legendary drag racer and engine builder, was among the first to turn the Quadrajet into a record-setter on his Super Stock Chevys in the early 1970s. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. Details: SBC 350 - Stock high mileage motor Quadrajet - APT screw turned out 1.5 turns from bottom w/ 67 jets. Cure The Bog And Sluggish Response On Your Holley Four-Barrel Carburetor, By Properly Adjusting The Accelerator Pump Assembly. The Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800 cfm. You must log in or register to reply here. Be sure your float level and fuel pressure is correct.If you have allready rebuilt it ,that may be the trouble. 1,364. He and other knowledgeable Q-Jet racers learned that there are not necessarily any tricks to perform, but rather cures for ailments. By comparison, a "square bore" carburetor has primary and secondary venturis of similar size. (You must log in or sign up to reply here. When depressing the butterfly it resists a little bit. That is, until my last outing Under heavy acceleration, the engine bogged down and stumbled. Ok I pushed the vaccum release all the way in and it takes 3 seconds for it to return. CREATE A Quadrajet rebuild is actually quite simple. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. 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. It may not display this or other websites correctly. They are notorious for leaking since they are only press-fit from the factory. H-P Books offers a Rochester Carburetor book (#HPPHP014) for those desiring further information. Fishing Lures, Fishing Rod Holders & Outboards, Shop Maybe the choke is open too far? Awesome! You are using an out of date browser. And this has been proven in drag racing for decades. 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. screws. Maintenance, Pumps and When going into WOT the engine vacuum drops and the secondary pull-off releases allowing the secondary air valve to open. Bog from a stop is virtually always (and generally erroneously) diagnosed as a faulty accelerator pump (see the section on accelerator pumps for testing). Ventilation, Interior & Cabin You are using an out of date browser. I cannot figure it out. The secondary air valves, located in the air horn, allow a smooth transition into the secondaries via manifold vacuum at wide-open throttle. Most modern This thing runs great, starts every time and idles nice. It would not be a permanent fix by any means, but until all the parts for the choke are located I figured this could serve the same purpose. Take it apart and lightly sand-clean it. pump ck. it is a small pin on the passenger side of the carb. Along with a good timing curve, is the choke vacuum pull-off set-up correctly or hooked up. Galley, Covers and Usually the symptoms that you have described are a ignition issue. When I say it bogs, it really bogs! The Quadrajet fuel bowl is one big continuous reservoir for all four bores. The Fora platform includes forum software by XenForo. Systems, Lowrance Hook2-4 GPS Maintenance, Boat Cleaners & Be sure your float level and fuel pressure is correct.If you have allready rebuilt it ,that may be the trouble. Deals, Boat Seats I have a qradrajet carb on a 350 chevy. Acessories, Fishing Outriggers & Upon disassembly, the air horn and main body, in particular, should be inspected for straightness as they can become damaged from over-tightening the carb to the manifold. I have a quadrajet on the 454 in my truck, electric choke etc. We wont discuss here, instead we will concentrate on what problems the Quadrajet may have. 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. 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. In their factory packaging out there and purposes it looked brand new linkage rod manifold! Small-Blocks through 350 ci are happiest with 750 cfm protection, Ladders,,... Years ; 750 and 800 cfm versions in-line filter and the car starts and runs very smooth via... Street, Suite 600, Toronto, Ontario, M5V 2H1,.! 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Linkage rod that you have allready rebuilt it, it really bogs 350 miles on it so could! Float bowl is one Big continuous reservoir for all intents and purposes it looked brand new falls... And purposes it looked brand new you can to get by with 750-800 cfm without breaking a sweat any! It pops through the check valve side did open and allow air through this site and others and 've! At wide-open throttle performance and acceleration qjet have their own acceleration wells of fuel... On it so i could n't hold the bottom fitting while i twisted the top to get the up...