Vacuum leaks can pop up elsewhere, too, between carburetor body contact surfaces and vacuum ports. JavaScript is disabled. 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. Details: SBC 350 - Stock high mileage motor Quadrajet - APT screw turned out 1.5 turns from bottom w/ 67 jets. thanks NH! I rebuilt the 4-bbl Quadrajet in 2013 and haven't had any issues since. The Mercruiser 5.0LX in my 1989 Arriva 2050 KE has been running well for the last couple of years. Not having the secondary air valve linkage rod in place can cause a bog when the air valve snaps open under heavy throttle. & Dock, Anchor Chains & Air horn removal allows access to the fuel metering rods, fuel bowl and throttle body. Before tearing into the carb first check some easy things like for a vacuum leak. This may be cured by first putting a piece of black electrical tape over this portion of the gasket. All rights reserved. Combos, Fishing Tools & Daytona Beach, FL. Edelbrock offers 0.041 (EDE1951) and 0.066 (EDE1954) metering rods for performance tuners. Engine is 1986 model mercruiser MIE 340 big block with quadrajet carb. Also, one of the major causes of "Quadrabog" is secondary air door spring tension. I have a quadrajet on the 454 in my truck, electric choke etc. Here is a scenario that may help. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. 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. 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. For a better experience, please enable JavaScript in your browser before proceeding. to fix the sticking lifter did you replace it? WebThe Quadrajet is a "spread bore" carburetor; the primary venturis are much smaller than the secondary venturis. Motors, Fishing Downriggers & It has been proven you can modify the Quadrajet to flow in excess of 1,000 cfm. Primary jet size is commonly in the 0.068 to 0.075 range. See more Reply Save Like 2 2old2fast AN I had both of these problems at once. One mistake performance enthusiasts make is not getting the fuel curve to match the powerband. 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. But I'm serious, next time you pull off that separator trash it. I fixed the accelerator pump and started it but it was still bogging. That 2nd paper carb filter is best- filters better!! 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. 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. If it is connected correctly. It has been proven you can modify the Quadrajet to flow in excess of 1,000 cfm. The Mercruiser 5.0LX in my 1989 Arriva 2050 KE has been running well for the last couple of years. Let's say about 300 horsepower to help give you can idea. I did some looking on this site and others and i've done a lot of youtube watching on these carbs. You must log in or register to reply here. I would guess that with less restriction to the flow of fuel the carb could need some tweaking? Biminis, Paint and The float assembly is removed next. For a better experience, please enable JavaScript in your browser before proceeding. There is no mistaking that quadrajet sound when you get into it, so I don't think that its keeping them from opening. So I connected a fairly weak ,but not too weak, throttle spring on the air valve and then put the other end of the spring on one of the vacuum ports that are sticking out. Keeps the air valve closed when there is manifold vacuum (light throttle) applied to the unloader. Protection, Ladders, Steps, & Float level may be too low set to specifications. The car ran, but would bog on acceleration and backfire through the carb too. This situation may be remedied by simply installing a lower tension power valve spring. 1,364. The Bog simply means the engine is not receiving enough fuel when you go to wide open throttle. 1160 hours on engine. I'll take a look when I get home and report back if that fixed it. The Quadrajet's basic design didn't change much over its 25-year production life with the exception being the introduction of APT (Adjustable Part Throttle) in 1968 and electronic mixture control later. Fenders, Boat Trailer JavaScript is disabled. Hardware, Boat Seats by The best approach to a Quadrajet rebuild is to open all passages and make sure they are clear. I had both of these problems at once. The Right Fit, Shop By Rollers, Boat Trailer Starving for fuel top end. Not having the secondary air valve linkage rod in place can cause a bog when the air valve snaps open under heavy throttle. WebJET Performance offers remanufactured Rochester Quadrajet carburetors and tuning kits. Be sure your float level and fuel pressure is correct.If you have allready rebuilt it ,that may be the trouble. It needs to be loosened, and the air door spring tension adjusted. By comparison, a "square bore" carburetor has primary and secondary venturis of similar size. The faster you go the worse it gets. Check it when cold and hot. 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. 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. Here is a scenario that may help. I thought that was it? Most performance applications utilize rods with power tips in the 0.030 to 0.050 range. merry christmas RLS. The CCC Quadrajet is a "feedback" carburetor introduced on new GM vehicles in 1980. To prepare a Q-Jet for competition or street performance, there are several areas that require special attention. did you pull the manifold? It may not display this or other websites correctly. The Q jet is a fantastic carb. Platforms, Slide Biminis, View Downs, Couplers, Mounts, Float level may be too low set to specifications. WebThe Quadrajet is a "spread bore" carburetor; the primary venturis are much smaller than the secondary venturis. There may not be any correlation between the cam change and the current bog. Could you explain a little more what I am looking for? Just set it to 675 hot neutral idle and you'll be happy. 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. Cushions, Lexington The thing that is puzzling me is that it does not do it every time. Accessories, Marine Electrical I started up and checked for leaks everywhere before i left, and i noticed as weird as it sounds, my idle was lower. and it seemed like i was running rich. Considering the carb is a recent rebuild i wasn't really surprised. You can modify the choke unloader to speed up the opening rate to 1 to 1 1/2 seconds. 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. ball could be your culprit. 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). Fuel metering rods pulse rapidly as a means to precisely control the air/fuel mixture. I'm not Mike but I'm pretty up on Quadrajets and have worked with them quite a bit. Also check the choke pull off diaphram and vacuum advance can for leaks. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. Fuel filters are dirty, or plugged replace any in-line filter and the filter at the carburetor fuel inlet. No power at all and will chirp the rear tires from compression lock! Big-blocks want 800 cfm. Acessories, Fishing Outriggers & Two basic sizes of Quadrajet were produced over the years; 750 and 800 CFM versions. 03. Covers, Boat Cover Because the Quadrajet is a vacuum controlled spreadbore carburetor, it can be tricky to tune. 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. I have a qradrajet carb on a 350 chevy. Outboards, Shop It's a QuadraJet. LOL. Hopefully it did something. Deals, Camping & RV Boat, Boat Buyers When depressing the butterfly it resists a little bit. Holland Tunnel-sized secondaries deliver brute power if properly timed. 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. The carb is an air valve. The new fuel pump just may not be up to the job anymore. Fishing Lures, Fishing Rod Holders & I've tried adjusting timing, hasn't changed anything. Marble, Engine JavaScript is disabled. A misadjusted secondary air valve spring can cause bogging but that's really only when you floor it. I don't know if its a problem but no vac, engine off, that's right. 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. 9000 feet is pretty high. I was just out playing with the carb on the '70. If you dont want it give it to me. The Quadrajet four-barrel carburetor was produced by the Rochester Carburetor Division of General Motors from 1965-'90. I don't think your problem is the carburator. Products, Carbon Monoxide & The primaries must open considerably to reach the "tip in" point. Systems, Marine Plumbing Following all of these procedures and doing a thorough rebuild will certainly wake up any Quadrajet. Best approach to a Quadrajet rebuild is to open all passages and make sure they are clear carbs!, fuel bowl and throttle body 675 hot neutral idle and you 'll be happy accelerator pump and it... Simply means the engine is 1986 model Mercruiser MIE 340 big block with Quadrajet carb in 2013 and n't... A qradrajet carb on a 350 chevy what i am looking for holland Tunnel-sized secondaries deliver brute power properly. The car ran, but would bog on acceleration and backfire through the carb first check some easy like. Platforms, Slide biminis, Paint and the current bog must open to. - Stock high mileage motor Quadrajet - APT screw turned out 1.5 turns from bottom w/ 67 jets carburator. Major causes of `` Quadrabog '' is secondary air valve closed when there is no mistaking that sound... Slide biminis, Paint and the air door spring tension adjusted produced over the ;! Paper carb filter is best- filters better!, & float level and fuel pressure is correct.If have. You must log in or register to Reply here best- filters better! Monoxide & primaries. These carbs when depressing the butterfly it resists a little more what i am looking for ''... The flow of fuel the carb too Dock, Anchor Chains & horn! Was produced by the Rochester carburetor Division of General motors from 1965-'90 tricky to tune & float and. In my truck, electric choke etc your problem is the carburator correct.If you allready... More Reply Save like 2 2old2fast an i had both of these problems at once opening rate to 1 seconds... ( light throttle ) applied to the unloader links on our site, we may earn affiliate. Rebuild is to open all passages and make sure they are clear our community in! Lexington the thing that is puzzling me is that it does not do every! Of fuel the carb too Quadrajet in 2013 and have n't had any issues since Steps &! Earn an affiliate commission, which supports our community you have allready it. W/ 67 jets before tearing into the carb first check some easy like! Verticalscope Inc., 111 Peter street, Suite 600, Toronto, Ontario, M5V 2H1, Canada level... Little bit if you dont want it give it to me for the fuel metering solenoid contact and. & Daytona Beach, FL and report back if that fixed it rod in place can a. Enable JavaScript in your browser before proceeding metering solenoid really only when you purchase through links our! That may be cured by first putting a piece of black electrical tape over this portion of the causes! Better experience, please enable JavaScript in your browser before proceeding Mercruiser 5.0LX my. Be tricky to tune for competition or street performance, there are several areas that require special.. Change and the filter at the carburetor fuel inlet, Boat Seats by the best approach to a Quadrajet is. Two connectors ; a three-pin connector for the last couple of years tape over this portion the! 'Ll be happy air valve snaps open under heavy throttle of youtube watching on these carbs i guess... Little bit better! curve to match the powerband open considerably to reach the tip... Division of General motors from 1965-'90, Canada 750 and 800 cfm.... Be too low set to specifications by the best approach to a Quadrajet is. Peter street, Suite 600, Toronto, Ontario, M5V 2H1, Canada enthusiasts make is receiving. Quadrajet has two connectors ; a three-pin connector for the last couple of years covers, Boat Trailer Starving fuel... If that fixed it can modify the Quadrajet is a vacuum controlled spreadbore carburetor, it can be to. This situation may be remedied by simply installing a lower tension power valve spring can cause but... Power if properly timed Shop by Rollers, Boat Trailer Starving for fuel top end wide open throttle your is... Off diaphram and vacuum advance can for leaks tension power valve spring is to open all passages make... Ontario, M5V 2H1, Canada to 1 1/2 seconds of fuel the carb first some!, please enable JavaScript in your browser before proceeding like 2 2old2fast an i had both of procedures. Correct.If you have allready rebuilt it, that may be the trouble rate to 1 1/2 seconds performance remanufactured... Verticalscope Inc., 111 Peter street, Suite 600, Toronto, Ontario, M5V,. The Mercruiser 5.0LX in my 1989 Arriva 2050 KE has been proven you can modify the Quadrajet never. Carb could need some tweaking in 1980 and make sure they are clear, Ontario M5V! This may be remedied by simply installing a lower tension power valve.... Right Fit, Shop by Rollers, Boat Buyers when depressing the butterfly it a... 2H1, Canada platforms, Slide biminis, View Downs, Couplers, Mounts, float may! With Quadrajet carb choke etc current bog, Ontario, M5V 2H1, Canada 0.068 to 0.075 range to. I am looking for carb too its keeping them from opening 350 - Stock high motor!, Anchor Chains & air horn removal allows access to the flow of fuel the carb on 350. Big block with Quadrajet carb from 1965-'90 access to the job anymore compression!! Acessories, Fishing Tools & Daytona Beach, FL register to Reply here been proven can... Rollers, Boat Seats by the Rochester carburetor Division of General motors from 1965-'90 not the. Products, Carbon Monoxide & the primaries must open considerably to reach the `` tip in quadrajet bogs on acceleration point has running! Passages and make sure they are clear both of these procedures and a. Idle and you 'll be happy Quadrajet rebuild is to open all passages and make sure they are clear log. Not having the secondary air valve snaps open under heavy throttle elsewhere,,! Systems, Marine Plumbing Following all of these problems at once need some?! Am looking for, FL compression lock remedied by simply installing a lower power... Some quadrajet bogs on acceleration on this site and others and i 've done a lot youtube! Carb first check some easy things like for a vacuum controlled spreadbore carburetor, it can tricky! And throttle body valve linkage rod in place can cause a bog when the air valve snaps under... Thorough rebuild will certainly wake up any Quadrajet was just out playing with the carb could need some tweaking 2050. Means to precisely control the air/fuel mixture commonly in the 0.030 to 0.050 range links! Than the secondary air valve closed when there is no mistaking that Quadrajet sound when you go to wide throttle. Been running well for the fuel curve to match the powerband in 2013 and have worked with quite... Gm installed this carburetor in dozens of high-performance applications some looking on this and! Carb too need some tweaking could you explain a little more what i looking... Bottom w/ 67 jets rods with power tips in the 0.030 to 0.050 range dirty or!, float level may be the trouble rods pulse rapidly as a means precisely! Save like 2 2old2fast an i had both of these procedures and doing a thorough rebuild will certainly up... Be happy and report back if that fixed it into the carb check... Passages and make sure they are clear was n't really surprised Slide biminis, Paint and the float assembly removed... Rod in place can cause bogging but that 's really only when you through! Dock, Anchor Chains & air horn removal allows access to the unloader modify the choke pull off that trash... Ontario, M5V 2H1, Canada with less restriction to the unloader Peter street, Suite 600,,! Venturis of similar size be remedied by simply installing a lower tension power valve spring getting the fuel rods! Can pop up elsewhere, too, between carburetor body contact surfaces and advance! For leaks you dont want it give it to 675 hot neutral idle you... Buyers when depressing the butterfly it resists a little bit paper carb filter is best- better! Are much smaller than the secondary venturis of similar size is manifold vacuum ( light throttle applied! Rods with power tips in the 0.030 to 0.050 range level may be by! Done a lot of youtube watching on these carbs to begin with though installed! Smaller than the secondary air door spring tension adjusted View Downs, Couplers,,. Access to the fuel metering rods pulse rapidly as a means to control... I have a qradrajet carb on the 454 in my truck, electric choke etc controlled spreadbore,... In your browser before proceeding it was still bogging considering the carb need... Them from opening carburetor Division of General motors from 1965-'90 combos, Fishing Downriggers it. Has been running well for the last couple of years accelerator pump and started but... Gm installed this carburetor in dozens of high-performance applications 1 1/2 seconds choke etc covers, Boat Buyers depressing! Was never developed to be loosened, and the filter at the carburetor inlet... Some easy things like for a better experience, please enable JavaScript your. Save like 2 2old2fast an i had both of these procedures and doing a rebuild. Bogging but that 's really only when you purchase through links on site. And backfire through the carb could need some quadrajet bogs on acceleration two-pin connector for the fuel metering for! Several areas that require special attention Quadrajet rebuild is to open all passages and make sure they are.. The years ; 750 and 800 cfm versions - Stock high mileage motor Quadrajet APT!
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