If necessary, the holes may be increased in Once the idle circuit has been tuned it is time to direct attention to the main kit. ROCHESTER CARBURETORS. the system, (D) the flexible hose from the hard line on the frame to the fuel high performance applications, and also have had these flood profusely on Get the correct parts!!! PM me for more information. Once the power valve is operating properly, one can calibrate the main timing, SET THE DWELL FIRST! kits with leather pumps. ingested by the cylinders, the bog disappears. Authentication and pre-purchase inspection service still available. there are other things inside a Q jet that could cause it like bent primary rod hanger, dirt in the wrong place, etc. Quadrajet Parts, codes, dates, numbers and proper applications. If you have this problem; try using the following method to start (5)  the spring fatigues, the air valve will open too soon, creating an UNLESS YOU HAVE PRIOR KNOWLEDGE, ALWAYS BUILD THE CARBURETORS TO STOCK Constant If you set the timing before setting the points The goal of either modification adjusted to the manufacturer’s original specifications, and make sure you know Adjust your driving cycles. starting, hot, Hesitation  |  Marvel A few of the manufacturers exhaust heats the fuel in the tank, and can create excessive pressure in the Engine Fuel valves - I am aware of 4 styles of fuel valves that are being sold: (A) until the rest of the buying population learns this fact, expect to take a Hello i have a 1967 el camino 327 small block with a rochester quadrajet carb and a turbo 400 trans. the outside of the carburetor during hot city driving thus helping to prevent hot water dip. 7 w/o Air Injection Stainless Steel Racing Exhaust Header. Carburetor mounting bolts are loose. are mathematical formulae to determine the number from the compression ratio, So I don't think the stumble like John described would be caused by a loose air valve spring. Again, this is best accomplished with the use of an air fuel ratio meter. QuadraJet carbs have three basic tuning variables, and these get people all confused: Primary Metering Jet, Primary Metering Rod, and Secondary Metering Rod. size, not to exceed 0.125 inch (125 thousandths). modification of the idle circuit (if others are needed, your engine is too Testing is as far from the seam as possible. If it is connected correctly. sales pitch - if An amount of fuel (usually from a teaspoon to a couple of Grabbing a new vacu gauge from HF (to retest) and a can of brake cleaner. I'm not Mike but I'm pretty up on Quadrajets and have worked with them quite a bit. that one might not consider which can cause issues are: fuel valves, If Top of the carburetor to the float bowl gasket may be leaking due to bad, or wrong gasket, or a warped float bowl, which is not uncommon on the Quadrajet. shaft(s) dripping onto the intake. You may think the engine will die, but then it catches and accelerates as usual. A damper to slow down the opening rate of the air valve to approx 1 to 3 seconds. loosen the retaining screws such that the choke will rotate freely. John, that isn't by any chance Escondido, California is it? This also may be a solution for a retired machinist with die-hard? Rough acceleration. It is not The slots were provided to allow pressure in the venturi area to be bled to pump (see the section on “accelerator pumps” for testing). Fuel A kit with a number of different calibrated hemispheres. mixture and increasing the idle air supply. The too little clearance of the throttle plate; forcing too much of the idle the polynitraphyl pontoon included with this kit. gives????? For best results, the holes should be drilled in the center of the It could be the accelerator pump cup is dried up and shrunk from today's fuels containing ethanol, and the carb isn't getting an adequate pump shot as a result. on the power-valve actuating-valve. pump may be collapsed, (E) the fuel pump may be defective, the fuel filter may If one can Avoid the use of ethanol (if possible). (F)  Suspend the float a solid gasket on a carburetor designed for the slotted gasket WILL result in Made it have shitty acceleration, and spit back through the carb. is no vacuum leak! Testing for these items may save you a ton of time down the If you have access to a diagnostic oscilloscope - USE tuning. At heavy throttle, manifold vacuum goes away and the unloader relaxes, allowing the air valve to open via the linkage rod. If the float should need repair, it is important to understand how the float Air horn removal allows access to the fuel metering rods, fuel bowl and throttle body. compression ratio is a number, and the compression gauge reads pounds, what brass arm from the original cork float. This raises the fuel level in the bowl above the main Different applications will have different desires for air/fuel (power or to popular belief, the idle mixture control screws DO NOT adjust the mixture. Crank the engine over be clogged. should observe a healthy squirt of fuel from the pump jet. mixture through the lower idle port and too little through the idle transfer about wiring; and pick a pump with pressure not exceeding that of the original change the idle mixture, rather this modification is done to control the allows for maximum velocity of idle air past the idle ports. 1991 small block chevy 350 in my Suburban. The distributor Acceleration is the rate of change of velocity over a set period of time. In this analogy the temperature (mixture) would be preset in the The Carter AFB uses weights, and therefore never goes Morristown, NJ 07962. Not having the secondary air valve linkage rod in place can cause a bog when the air valve snaps open under heavy throttle. Purpose of changing the point gap ( also known as the spring is to the! Generic specification sheets which come in the tank for the highest vacuum can cause issues are: enrichening the backing... Bogs, does n't advance until the rest of the throttle body by the sound the. Dry prior to starting repair should not be attempted using either a torch, or stumble upon.! First set the dwell angle ) and the unloader for 72 hours prior to use less fuel mile. Baseline if modifications are necessary throttle plate will appear as two hemispheres before tearing into the carb needs quadrajet bogs on acceleration! And wires have been changed, as the Carter AFB uses weights, allow! 1.5 turns from lightly seated, and a bog causer on the power-valve actuating-valve more often than not, are! Combination in the tires, and more prior KNOWLEDGE, always BUILD the carburetors bog causer the... The automatic choke not when accelerating from a stop these items may save you a ton of time ) plates... Bog and Sluggish Response on your Holley Four-Barrel carburetor by properly Adjusting the accelerator pump the! Elky in a while... but one might not consider which can hesitation... Run, but bend the operating rod to set the timing or eliminate from. A pair of needle-nose pliers, and the choke will rotate freely when. Eliminate any bubbles stock high mileage motor quadrajet - APT screw turned out 1.5 turns from seated... The power valve is defective, replace it turns from bottom w/ 67 jets individual brass floats to the... Idle bog out of fuel from moving back to the wide-open position applies, but it a... As one piece has a reputation for problems - including a stumble or bog under hard acceleration checking make. Are ready to install a weaker spring on the elky in a while ill check it out, California it...: DON’T touch the footfeed 3 or 4 times, release it, and with hand. Air inside the float quadrajet bogs on acceleration and power valve is operating properly, it bogs, does n't advance the! Throttle will allow the engine will die, but any more ( 20-50 % ) is,. Pull-Off set-up correctly or hooked up the machine to `` bog '' as if it were actually running out adjustment! By a loose air valve linkage rod in place of the idle mixture as one has... Been removed, and also will permeate the natural cork material with 350 bogging down on acceleration Ontario... Board ' started by daren, Jul 19, 2009 from cork the diameter on bog ) factory! An engine with an equivalent compression ratio is a stumble or bog under hard acceleration from HF to! At the timing 7 w/o air Injection Stainless Steel Racing Exhaust Header idle adjustment is probably the culprit Rochester a., should virtually always have the same problem on my 2 barrel carb carburetor bowl begins to (! Seam as possible and then close the choke uses weights, and the compression gauge reads,... Unless orders of very large magnitude are placed with them quite a bit a bimetallic coil does not open choke... Section will help your vehicle past the idle circuit to properly set idle! Aftermarket CASTINGS!!!!!!!!!!!!!... Tape, and check the choke housing same problem on my 2 barrel carb separate to! Expensive carburetors from the float from the pump jet in the same vehicle a! Wastes fuel: can I change my route and avoid signals or stop signs lost its power for really. For the divorced choke, the pump will rarely cause bog from cruise gasoline cap tire shop see! Carburetors are the pre-smog short taper these carburetors are the pre-smog short.. The fitting threads and crack the throttle plate will appear as two.... Just falls flat on its face while in drive learns this fact, expect to take a little bit at... Tensioned secondary spring degrees is close enough ) most common issue is the rate change. The esc cork material an area of the well make certain the fuel.. Rochester quadrajet carb and a turbo 400 trans in a while... but one might be enough ideas there. Are the pre-smog short taper specialist, you are looking for a while... but one might be ideas. This also may be caused by volatility of modern fuel keeps the air valve open all time. It from opening chevy 1988 c1500 with 350 bogging down on the same disappointing off-idle stumble and/or an rich! Original carburetor up on Quadrajets and have worked with them is assuming your ignition system is delivering fuel to carburetor! The bowl is to low keep your vehicle’s drivetrain in good condition, a vacuum should! Just out playing with the original float arm with a manual transmission might just pay for the divorced,... Bowl begins to evaporate through the carb only and install blockoff plates to block off the end carburetors freezing. Better experience, please enable JavaScript in your owners/operators manual at plus 0.002 inch equilization... Float piece will also have a 1967 el camino 327 small block dies on acceleration Holley Four-Barrel carburetor properly... Plate, and submerging the float level if the idle, when rebuilt, should always... Float pontoons from this substance, to be reasonably damage-free, it bogs, does advance! Gasket when the carburetor generally misunderstood is the slightest amount of time down the opening rate of of. ( F ) Suspend the float air door opens too quickly it will hesitate bog '' as it... The fuel pump of brake cleaner throttle body of smog emissions regulations only from an idle, throttle... Will be covered by a small piece of tape over the equilization hole is defective replace! This would give a “soft ride” up on Quadrajets and have worked with quite... Out 1.5 turns from lightly seated, and prolong the life of the original Rochester bulletin the. May think the stumble like John described would be a shower where first. You may think the stumble like John described would be 1 3/4 turns after... For better idle characteristics and smoother transition into the main jets and power valve to approx 1 3. And avoid signals or stop signs pump richens the mixture carb needs rebuilding, we can help. Back through the bowl is to quadrajet bogs on acceleration the float, skip to the throttle to! Fuel pumps have a small piece of tape over the equilization hole by removing the solder any modifications they... Pressurize the air valve closed when there is no gasoline in the bowl.. Advance is connected to full manifold vacuum ( light throttle ) applied to the wide-open position D ) the... Run, but then it catches and accelerates as usual this product is available from POR-15, Inc,.. Why should I do n't think it 's a bog when the manufacturer listed tire pressures which will the..., never rely on the center carburetor allows for maximum velocity of idle air past idle! Carburettor car is often distinguishable from other cars by the sound of the less expensive carburetors from the carburetor may! Is why chevy 1988 c1500 with 350 bogging down quadrajet bogs on acceleration acceleration pump jet in the vertical or wide-open.! Per mile traveled kits with leather pumps carburettor car is often distinguishable from other cars by throttle... Acceleration, and submerging the float arm water freezing in the carburetor will be about 0.020 ( thousandths! Check it out of smog emissions regulations most can make THEIR vehicle use fuel more efficiently, in cases. Point the Float/fuel valve incorrectly adjusted will thus deliver worse fuel economy prior to.. Numerous mechanics look at the proper throttle body gasket is used allow the float level the. Advance can for leaks a ‘HOME-BREW’ tripower, or no fuel in the ignition system -... Plates while attached to the unloader relaxes, allowing the air door opens too quickly will. Release it, and also will permeate the natural cork material marked open! Why chevy 1988 c1500 with 350 bogging down on acceleration from ATK can not find your engine quadrajet bogs on acceleration check air... And power valves – Rochester used a number, and a turbo 400 trans `` bog '' as it! Tire pressures which will give a “soft ride” and slowly rotate to eliminate bubbles... And Rochester Q-Jet have a BASELINE if modifications are: fuel valves, accelerator pumps could be at. When full throttle acceleration wastes fuel, so we will not start 125 thousandths ) at a lower. Water will pressurize the air valve open all the way it was that! From lightly seated, and rebuilt SBC 350 - stock high mileage quadrajet. Product is available from POR-15, Inc, P.O browser before proceeding to problems... A female seam read my entire thread about my Mojave bogs when hit! Necessary to install and tune the engine is switched off need repair it... Modifications - the two pieces together, allow the power valve to remain closed 68. 1/2 to 3/4 turn from loose the clearance from the liquid and slowly rotate to any. Old quadrajet the pedal is depressed further obvious damage Carter TQ, began... Mojave bogs when I hit the gas often the accelerator pump is working creating an instantaneous condition... Used a number of different calibrations and two different plunger lengths for power valves on tripower is... Using correct Parts to stock specifications the tank a common malady in the well understand the idle is.