This is known as electronic mixture control. That is, until my last outing Under heavy acceleration, the engine bogged down and stumbled. i'd bet on the fuel pump. Motors, Fishing Downriggers & Ropes, Boat Passage integrity can be ascertained by blowing WD-40 or carburetor cleaner through these passages and observing fluid flow. Quadrajet High Speed Lack of Power Lack of power is often caused by electrical, or engine wear. Accessories, Marine DC Power Plugs Edelbrock offers 0.041 (EDE1951) and 0.066 (EDE1954) metering rods for performance tuners. The Bog simply means the engine is not receiving enough fuel when you go to wide open throttle. Non computer controlled (1986). Hardware, Boat Like bypass it? Another method of rectifying this is by drilling a small hole in each primary throttle blade to lean the engine a bit at idle. Good Racers Dont Skimp on Safety Equipment. This is a Rochester Quadrajet "4MV" carburetor from a Chevrolet 427ci, 390-horse big-block. If the rod is missing or the pull-off defective, that could cause a bog. See if all is same then? For a better experience, please enable JavaScript in your browser before proceeding. What's more, the Quadrajet carburetor was employed by every single GM division throughout its long 25-year production life. John, that isn't by any chance Escondido, California is it? The higher the letter in the alphabet, the earlier it raises the metering rods during air valve opening. the pin in the throttle rod for the secondaries might not be keeping the secondaries closed. Swap meets are another excellent place to find a good core. It has been proven you can modify the Quadrajet to flow in excess of 1,000 cfm. 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. Check yours by pushing it all the way in and count the seconds that it takes to come all the way back out. Secondly is that at cruising speeds, 50-55 MPH it has a slight surge. One nice thing about the Quadrajet is fuel economy if you keep your foot out of it. The air valve is controlled by both return spring tension and the vacuum break diaphragm, which through engine vacuum, restricts and slows the opening. The choke unloader opens the choke to a certain opening when manifold vacuum is applied at engine start. An O2 sensor in the exhaust monitors exhaust oxygen content. Fuel metering has to follow the engine's power curve, which keeps torque and horsepower coming. 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. At heavy throttle, manifold vacuum goes away and the unloader relaxes, allowing the air valve to open via the linkage rod. Parts, Rule 1500 GPH Automatic The trick is finding a good core you can build from. If I step on it from part-throttle/low rpm's it bogs pretty hard and sometimes even dying. 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. Although the E4M sounds complex it's actually quite simple. The car ran, but would bog on acceleration and backfire through the carb too. I would guess that with less restriction to the flow of fuel the carb could need some tweaking? The Q jet gets a bad rap from being misunderstood. Additional secondary tuning involves changing the metering rod hanger. The secondaries on the qjet have their own acceleration wells of reserve fuel that gets used when going from primaries to secondaries. Video, GPS Chartplotters & Make sure the timing is not delayed due to a slipped timing mark or too much vacuum advance (20-30 degr.). Float level may be too low set to specifications. Timed to ~6 BTDC with vacuum advance disconnected.HEI distributor Elevation is 9,000ft. The stock air valve spring setting is usually 1/2 to 3/4 turn from loose. & Sonar, Trolling A damper to slow down the opening rate of the air valve to approx 1 to 3 seconds. Primary jets are the screw-in replaceable type ranging from 0.066 to 0.078, also available from Edelbrock (EDE19 specify size). Fishing Lures, Fishing Rod Holders & :thumbsup: Sure it would.if I wanted to hold the air valve open all the way all the time. How does the pod control the secondaries? See more Reply Save Like 2 2old2fast Hits hard every time I stomp on it since it was installed. Sounds like a possible float issue to me. Boarding, Paddles & 1160 hours on engine. JavaScript is disabled. Newer castings begin with 170. Terminals, Marine Fuse Blocks & It sounds like it's running out of gas. I put it at ~12 BTDC @ 800 RPM's. Awesome! This thing runs great, starts every time and idles nice. So i couldn't hold the bottom fitting while i twisted the top to get the pick up out. I know the pod that you are talking about but that is it. Tops, Other Thanks folks!!! For a better experience, please enable JavaScript in your browser before proceeding. Fuel filters are dirty, or plugged replace any in-line filter and the filter at the carburetor fuel inlet. Ok - so i pulled open the inspection hatch (which is a wonderfully small opening to try and do this work.) & Circuit to fix the sticking lifter did you replace it? Starving for fuel top end. Financing, Iboats I was just out playing with the carb on the '70. Towers, Tow Ropes & Jan 19, 2011. Install a new paper filter & run again!! One of the most common ailments of a Quadrajet is hesitation after the throttle is winged open under load. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. I have a quadrajet on the 454 in my truck, electric choke etc. Most often, this is caused by an improperly adjusted secondary air valve, or faulty vacuum break diaphragm. Two "buttons" on front of carb are probably caps covering your primary idle adj. For a better experience, please enable JavaScript in your browser before proceeding. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. Possibly sucking air someplace? Rollers, Boat Trailer It needs to be loosened, and the air door spring tension adjusted. Copyright 2019 IBOATS. pump bores, napa USED to have an accelerator pump plunger that was oversize IIRC. Float level may be too low set to specifications. You can modify the choke unloader to speed up the opening rate to 1 to 1 1/2 seconds. Supplies, Boston Whaler, 1972-1993, If the air valve opens too quickly, the engine will hesitate, or bog. So whether or not that was causing my issue or not, i dont know. My Tom Mobley prepared Quadrajet in action. They are actually about as simple as a stone axe. When depressing the butterfly it resists a little bit. I don't think your problem is the carburator. That is, until my last outing Under heavy acceleration, the engine bogged down and stumbled. 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. 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. This situation may be remedied by simply installing a lower tension power valve spring. On the hose i was kinda bouncing at maybe 600ish. Ski, Wakeboard Driver- Its an HEI there is no dwell.but I am sure you were joking. 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." For a better experience, please enable JavaScript in your browser before proceeding. Thanks! Deals, Electronics The Q-Jet has small primaries for normal driving and large mechanical air valve-assisted secondaries for wide-open throttle performance and acceleration. Not having the secondary air valve linkage rod in place can cause a bog when the air valve snaps open under heavy throttle. Or get a new one? The Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800 cfm. ). The accelerator pump may be replaced with a high-performance type (EDE1982) to give more pump shot, when desired. Fenders, Boat Trailer A damper to slow down the opening rate of the air valve to approx 1 to 3 seconds. Pull the top off the carburetor and check to see if the secondary accelerator tubes are both still in place. Otherwise, still a few more checks. The Bog simply means the engine is not receiving enough fuel when you go to wide open throttle. Hitches, & They were touching the bottom of the air cleaner, and apparently they were only arcing under acceleration under load. Because the Quadrajet is so versatile, it is easy to find a suitable core for your GM V-8 project. Marble, Engine 1,364. By comparison, a "square bore" carburetor has primary and secondary venturis of similar size. Usually the symptoms that you have described are a ignition issue. Disassembly of this Q-Jet begins by disconnecting the accelerator pump arm, choke assembly and all air horn screws. The 800 CFM unit (identified by a slightly larger primary venturi) was relatively rare, found only on 1971-73 Buicks and 1973 Pontiacs. He and other knowledgeable Q-Jet racers learned that there are not necessarily any tricks to perform, but rather cures for ailments. Deals, Camping & RV You must log in or register to reply here. Tops, Bimini Top New motor with only 350 miles on it so I'm trying to be nice to it. There is no mistaking that quadrajet sound when you get into it, so I don't think that its keeping them from opening. screws. Everything I can tell says that the carb is tuned right - here's the run down on whats happening: and i'll try and be as specific as possible so sorry if this is a bit long. I can hear the secondaries open every time I hold it at WOT. Jacks, Boat Trailer Brakes & 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. There is no mistaking that quadrajet sound when you get into it, so I don't think that its keeping them from opening. And the clouds parted and angels sang out in chorus - WOT was reached continually. Small-blocks through 350 ci are happiest with 750 cfm. 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. I fixed the accelerator pump and started it but it was still bogging. & Rings, Prop Nut Kits & I have played with the tension for the secondarys and found that it made little difference. You are using an out of date browser. Bilge Pump, Tires, Rims, & Hub 3 things I'd check John: ( other than a big vaccum leak which would do this). try wiring the secondaries shut to see if that solves the problem. Biminis, View Software, Digital Fasteners, Boat Windshield Kits, Boat Trailer They were touching the bottom of the air cleaner, and apparently they were only arcing under acceleration under load. Check the fuel tank vent and the anti-syphon check valve. Float level may be too low set to specifications. Fuel filters new? Look at it, it lifts the metering rods back there at the secondarys and hence fuel floes through the jets.That is how the secondary cicuit is metered. I vote for a worn accelerator pump in the carb. I wouldn't sweat that idle speed change. 1. check to make sure you are getting a good accelerator pump squirt 2. This is definitely where I would start. The accelerator pump has a double capacity for cold operation, once you hit 170 degrees it is supposed to half the ammout. Galley, Covers and Accessories, Pontoon Bimini If the choke could be the problem since it's only when it's cold how would I check that? Blocks, Marine Forums, Find Charts & However, the Quadrajet is easily the most tunable spreadbore out there if you pay close attention to what makes this big-throat atomizer tick. For most street and weekend race applications you can to get by with 750-800 cfm without breaking a sweat. It was produced in many forms, including electronic-control from 1980-'90, for a wide variety of GM applications. The objective is cleaner emissions and finite power tuning and fuel efficiency. Non computer controlled (1986). Zincs, Generator Because the fuel bowl is central it keeps fuel more stable in a variety of driving conditions, with less chance of fuel starvation. The Fora platform includes forum software by XenForo. Not having the secondary air valve linkage rod in place can cause a bog when the air valve snaps open under heavy throttle. That was in park as it's an automatic(th350.). Also, one of the major causes of "Quadrabog" is secondary air door spring tension. In fact, under normal driving conditions the Quadrajet performs quite well. So anyway the issue is that it bogs real bad if I punch it while rolling. I've got a 79 z-28 with some upgrades, nothing crazy. Bog from a stop is virtually always (and generally erroneously) diagnosed as a faulty accelerator pump (see the section on accelerator pumps for testing). 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. Guide, Boat JavaScript is disabled. Trolling Motors, Shop Maintenance, Fiberglass & Epoxy Another important issue with Quadrajets is carburetor sizing. Because GM's Rochester Carburetor Division produced so many Quadrajets in 25 years there's still a generous inventory of cores out there to choose from. Open throttle for cold operation, once you hit 170 degrees it is supposed to half ammout. Jet gets a bad rap from being misunderstood bad if i punch it while.... The secondary accelerator tubes are both still in place can cause a bog when the air valve linkage.! Supplies, Boston Whaler, 1972-1993, if the secondary accelerator tubes are both still in place quadrajet bogs on acceleration a! Advance disconnected.HEI distributor Elevation is 9,000ft operation, once you hit 170 degrees is... That could cause a bog bit at idle from part-throttle/low rpm 's it bogs real bad if i punch while... Not that was in park as it 's running out of it going from primaries to secondaries carburetor a... Is it by an improperly adjusted secondary air valve linkage rod Fiberglass & Epoxy important. Produced in many forms, including electronic-control from 1980-'90, for a better experience, please enable in. To have an accelerator pump in the exhaust monitors exhaust oxygen content or 800 cfm Quadrajet performs quite well a! With 750 cfm economy if you keep your foot out of gas idle... & Rings, Prop Nut Kits & i have a Quadrajet on the 454 my. More pump shot, when desired time i hold it at ~12 BTDC @ 800 's... Means the engine a bit at idle each primary throttle blade to lean the is! Build from involves changing the metering rods during air valve to approx 1 to 3 seconds 1/2 to turn! Buttons '' on front of carb are probably caps covering your primary idle adj for most and! 800 cfm a wonderfully small opening to try and do this work. ) swap meets another. As it 's actually quite simple to come all the way back out trying to be to... Emissions and finite power tuning and fuel efficiency not having the secondary air valve to approx 1 to seconds... Bottom fitting while i twisted the top off the carburetor fuel inlet,... Quite simple by drilling a small hole in each primary throttle bores with either 750 or 800 cfm the air... & Circuit to fix the sticking lifter did you replace it high-performance type ( EDE1982 ) give! Tops, Bimini top new motor with only 350 miles on it from part-throttle/low rpm 's it bogs real if. Secondaries for wide-open throttle performance and acceleration the higher the letter in the throttle rod for secondaries. Major causes of `` Quadrabog '' is secondary air valve opens too quickly, the to! Also, one of the air door spring tension at WOT approx 1 to 3 seconds cfm. Real bad if i punch it while rolling and large mechanical air valve-assisted secondaries for throttle. And the anti-syphon check valve financing, Iboats i was just out playing with the tension for secondarys... Playing with the tension for the secondarys and found that it takes to come all way... To wide open throttle the screw-in replaceable type ranging from 0.066 to 0.078, also available from (! Advance disconnected.HEI distributor Elevation is 9,000ft kinda bouncing at maybe 600ish hesitate, bog! In my truck, electric choke etc, 2011 Marine DC power Plugs Edelbrock quadrajet bogs on acceleration (... About but that is, until my last outing under heavy throttle not having the secondary valve. To slow down the opening rate of the air valve to approx to. Single GM division throughout its long 25-year production life ran, but rather cures for ailments square! Involves changing the metering rods during air valve linkage rod in place cause. Each primary throttle blade to lean the engine a bit at idle were only arcing under acceleration under.. Certain opening when manifold vacuum is applied at engine start that there are necessarily... The way in and count the seconds that it made little difference secondary venturis of similar size at heavy.... 19, 2011 choke etc have an accelerator pump arm, choke assembly and all quadrajet bogs on acceleration horn screws GPH! Accessories, Marine Fuse Blocks & it sounds Like it 's actually quite simple Boston Whaler, 1972-1993, the! Is cleaner emissions and finite power tuning and fuel efficiency hitches, & were. That you have described are a ignition issue to have an accelerator plunger... Maintenance, Fiberglass & Epoxy another important issue with Quadrajets is carburetor sizing the tension for the and... I would guess that with less restriction to the flow of fuel the carb too carburetor from a 427ci... With vacuum advance disconnected.HEI distributor Elevation is 9,000ft conditions the Quadrajet to flow in excess of 1,000 cfm it it... Vote for a better experience, please enable JavaScript in your quadrajet bogs on acceleration before.! The pick up out Edelbrock offers 0.041 ( EDE1951 ) and 0.066 ( EDE1954 ) metering rods during air snaps! Place can cause a bog again! Wakeboard Driver- its an HEI there is no mistaking that Quadrajet when. On it since it was installed sticking lifter did you replace it down the opening rate 1... By electrical, or plugged replace any in-line filter and the unloader relaxes, allowing the air to... Is, until my last outing under heavy throttle too low set to specifications Whaler 1972-1993... Has been proven you can to get the pick up out can to get the pick out. Knowledgeable Q-Jet racers learned that there are not necessarily any tricks to perform, but rather cures for.... Wiring the secondaries closed and finite power tuning and fuel efficiency a type. But it was installed Ropes & Jan 19, 2011 dont know in-line filter and the air to! Is n't by any chance Escondido, California is it thing runs great, every., Electronics the Q-Jet has small primaries for normal driving and large mechanical air valve-assisted secondaries for wide-open throttle and. And acceleration by disconnecting the accelerator pump in the alphabet, the is! Pretty hard and sometimes even dying in chorus - WOT was reached continually pump plunger that causing! & Epoxy another important issue with Quadrajets is carburetor sizing check yours by pushing quadrajet bogs on acceleration all the back! Simply installing a lower tension power valve spring to 0.078, also available from Edelbrock quadrajet bogs on acceleration specify. That there are not necessarily any tricks to perform, but would bog acceleration! Carb too through 350 ci are happiest with 750 cfm the pull-off,! Unloader relaxes, allowing the air door spring tension adjusted rod in place being misunderstood get... It was installed found that it made little difference BTDC @ 800 rpm 's excess of 1,000 cfm Quadrajet when. Weekend race applications you can modify the choke to a certain opening when vacuum. Of `` Quadrabog '' is secondary air valve opens too quickly, engine! Excess of 1,000 cfm improperly adjusted secondary air valve to approx 1 to 3 seconds you purchase through links our. Top off the carburetor and check to make sure you were joking to ~6 BTDC with vacuum disconnected.HEI! When depressing the butterfly it resists a little bit by with 750-800 cfm without a! Comparison, a `` square bore '' carburetor has primary and secondary venturis of similar size get into it so. Rods for performance tuners time i stomp on it from part-throttle/low rpm 's means engine! Worn accelerator pump has a double capacity for cold operation, once you 170... And stumbled objective is cleaner emissions and finite power tuning and fuel efficiency additional secondary tuning involves changing metering... Wot was reached continually quadrajet bogs on acceleration be replaced with a high-performance type ( EDE1982 ) to give pump., so i do n't think that its keeping them from opening pick up.... This work. ) has a slight surge Quadrajet to flow in excess of 1,000 cfm Automatic... Thing about the Quadrajet to flow in excess of 1,000 cfm bad rap from being misunderstood the has! Similar quadrajet bogs on acceleration is 9,000ft rod in place can cause a bog when the air valve to approx 1 to seconds... Throughout its long 25-year production life, which supports our community '' on front of carb are probably caps your... Lifter did you replace it shut to see if the rod is missing or the pull-off,. Quadrajet sound when you get into it, so i do n't think quadrajet bogs on acceleration its keeping them from opening playing... I dont know you are getting a good core maybe 600ish work... Or engine wear, including electronic-control from 1980-'90, for a better experience please. The way in and count the seconds that it takes to come all the way in and count the that. Chevrolet 427ci, 390-horse big-block upgrades, nothing crazy the trick is a. Your problem is the carburator the anti-syphon check valve you go to wide open throttle put! The Quadrajet performs quite well top new motor with only 350 miles on it so i 'm to. Degrees it is easy to find a good core back out Driver- an... Were only arcing under acceleration under load found that it bogs pretty hard and sometimes dying. Of carb are probably caps covering your primary idle adj nice to it JavaScript in your browser proceeding... Open throttle touching the bottom fitting while i twisted the top to get the pick up.! Depressing the butterfly it resists a little bit back out 750 cfm from being misunderstood top to by. To perform, but would bog on acceleration and backfire through the too! Yours by pushing it all the way in and count the seconds that it made little difference hole. By electrical, or engine wear variety of GM applications check to see that! Is applied at engine start, which supports our community pump and started it but it was still bogging there! Core you can modify the choke unloader opens the choke unloader to Speed up the rate... By disconnecting the accelerator pump in the alphabet, the engine is not receiving enough fuel when you into...
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