quadrajet throttle sticking. In the pictures below, the left one is the "new" one, and the right is my original. Then track the fuel line down to the carburetor and remove the hose. Some Quadrajet applications use a shim between th e throttle body and flange gasket. Many automatic chokes have rods linking the choke to the throttle. On top of the throttle body of a fuel injected motor or carburetor is a butterfly valve, which opens when the accelerator pedal is pushed and the cable pulls it open. I'm a mechanic for more than twenty years, I've cleaned more throttle bodies. In most cases these numbers can be used to identify the year and application the carburetor was originally used on. Chevrolet was the first and only GM manufacturer to use the 4M Quadrajet in 1965. We know the difficulties involved in swapping overdrive automatic transmissions (200-4r and 700r4) into older muscle cars. Checking and adjusting the choke valve on the carb. Does the throttle cable open the throttle all the way. The "M" after that, is a style/model type. Details: SBC 350 - Stock high mileage motor. Q-Jets are a nightmare, most people just ditch em and get a carter style carb from edelbrock. The early carbs all have a factory spec of ¼”. I don't know about eledlbrock carbs? Never used one, I'm a Holley carb man. I plan on building this 800 cfm model that came off a 85 Buick station wagon with a blown up 307 swirl port motor, had it for 23 years to replace the current super lean current 83 carb on the 70S. if not loosen the screws slightly and with the throttle held closed tap the blade with a brass drift to locate the blade and retorque the screws. The large flat area on the main body just above the secondary throttle shaft has a series of numbers stamped into the casting. It almost sounds like the primary throttle plates are sticking in the bore. Re: Quadrajet operation question The secondary air valves will not open until the vacuum releases inside the carb as you throttle up. Trouble Shooting Guide For Quadrajet. weekend-warrior February 19, 2022, 1:51am #2. quadrajet idles high need some advice. This weekend, I was once again working on a guy's car that was suffering from eratic idle once warmed up, and the idle mixture screw on the passenger side. Set the fast idle on the second step of the cam, usually approximately 1100-1200 rpm when engine is warm. 10-28-11 04:34 PM - Post# 2152176 In response to ss3964spd Shows that people have NO concept of how things work correctly. A Quadrajet is a unique carburetor in that it has small primary plates and huge secondary plates. Great for fine tuning your Quadrajets cruise Air/Fuel metering. We ship parts same day or next day 99% of the time. That didnt work, so I pulled the throttle cable completely out of the truck along with the pedal. As you can see the vacuum ports are on 1 side for the new one vs both sides on the old one. Use thin wire to clean out the passages completely. If I step on it from part-throttle/low rpm's it bogs pretty hard and sometimes even dying. carcraft tested one from summit and it was typical- too rich, 11. Newly designed fully assembled, 21/32" Rochester pump assembly to withstand todays fuel with alcohol / ethanol. When I start the truck, it will idle at about 1200 RPM until the choke starts to open, The fast idle cam will "Step down" from 1200 RPM to 900 RPM after about 30 seconds, and then to 700 once the choke opens fully. quadrajet stuck wide open! Jump to Latest Follow 1 - 8 of 8 Posts. Some Quadrajet applications use a shim between the throttle body and flange gasket. Hi, I when I hit the gas pedal, at WOT, the carwill get stuck in full throttle The carb is the stock Quadrajet (4MV I guess) that comes up with the L48 350. Being a stock motor I'd stick with the qjet, if the motor was modified the a Holley might make a difference depending on cfm (vs qjet) and/or choke and secondary configuration. JET quadrajet bushing service kits will restore your throttle valve assembly to better than new tolerances. This float fits these original General Motors Rochester QuadraJet Carburetors 4M, 4MC, 4MV, M4M. The AV is the flap that covers the secondaries of your carb. Hi, I when I hit the gas pedal, at WOT, the carwill get stuck in full throttle The carb is the stock Quadrajet (4MV I guess) that comes . com is providing this video about what the secondary lockout does and how to adjust it. So I went on eBay and bought a throttle body for a 4 barrel Quadrajet carb. When discussing Quadrajet models, the number 4 means a four-barrel carburetor. Throttle body blades are different metal than an old quadrajet or holley blades. Hesitation under heavy throttle: Deadspot & stumbles. The Rochester QuadraJet uses an automatic choke system that is actually very good, if properly set up and adjusted. Are both your springs pulling in one . sometimes the cable is adjusted too short and slightly pulls on the throttle. 1) The throttle gets "sticky" alot; i can put my foot under the gas pedal and lift up and that brings the rpm's back down, so it's not too serious. Quadrajet isn’t clogged and make sure the fuel pump is suppling adequate fuel pressure and flow. It is bad enough to kill the engine sometimes. The power valve may be sticking. The throttle body is aluminum to reduce overall weight and to improve heat distribution, plus there is a thick throttle body to bowl insulator gasket to keep excessive heat from the float bowl causing fuel percolation. Disregard Code 24 if it is set when the drive wheels are not. According to my research, the ideal vacuum pressure for the Quadrajet is 18-in-Hg (inches of mercury). Since my mechanic used bolts that were just too short to secure the carb to the intake manifold, I went to the local ACE Hardware and purchased a few (longer) Grade 8 bolts and washers. when the engine is up to temp if I put my hand over primaries or choke the engine it runs faster. It may be the carb at fault but check everything, even the floor mat or carpet. The Edelbrock Performer Q-Jet #1904 runs $435-$450 at Jegs and Summit. 1970 Chevrolet C20 Custom Camper Pickup. Re: Sticking Open Secondaries on a Quadrajet The legs are just a rebuilding stand,handy but optional. The air horn is removed as well as the primary choke & the secondary air valves. Everyday Performance LLC has custom designed and produced a throttle arm conversion kit that enables older Quadrajet carburetors to be used with 200-4r and 700r4 overdrive automatic transmissions. WD40 won't be an effective throttle body cleaner, hard deposits stuck to the throttle body and throttle plate will require a throttle body solvent. Your Throttle Is Stuck At Full Power. Some Quadrajet models incorporate the lockout at the upper choke housing linkage while others locate the lockout at the secondary throttle shaft. One, the Air Horn which by the way looks like a horn on top and is the uppermost casting of the 3 pieces. All stick floats have two halves, a buoyant top section and heavy bottom half. See the picture for measurements. I do have check valve in the fuel filter. Unless you remove it completely. "On final descent after a training flight practicing ground reference maneuvers, I pulled back the throttle all the way back and noticed that it only went down to 2200 RPM (it usually goes down to 1500 RPM). Check all wiring and connections between the TPS and the ECM. QuadraJet vs Standard with Adapter. The throttle will not return all the way back to idle with . Adjustable Part Throttle (APT) screw allows adjustment of height of primary metering rods within the primary jets. They are vacuum actuated if I remember correctly and you won't be able to get them to move simply by rotating the throttle (with motor off). The ZA-01 Throttle Shaft Repair kit will service Rochester Quadrajet carburetors, as well as other carbs with 5/16� throttle shafts. Ray's Chevy Restoration Site. tried adjusting idle mixture screws to no avail, will run faster or slower as screws are moved but idles poorly. 5 turns out and it wouldn't idle. com member lars Just thought I'd pass on a little tip to those of you running Q-Jets. (I bet no one ever drilled them out that big, either-lol) Also, drilled idle discharge ports to. Solving Holley Sniper High Idle Issues. I have a rebuilt Quadrajet on a Chevy 350. the earlier versions are much harder to adjust. Driven moderately it returns fine mileage but hard driving opens those secondaries resulting in great power with the resulting poor mileage. It needs to move up and down freely. I recently obtained a 1985 c20 with a 5. I've got the casing all put back together and cleaned etc. I adjusted the idle mixture screws and the best reading I got was about 17½-in-Hg. Quadrajet Accelerator Pump Assembly, 21/32" High Performance garter springOur Part # 1003. Using bronze bushings, the kits eliminate common problems such as vacuum leaks, inconsistent idle speeds and binding or sticking throttle. The Quadrajet became the most popular and widely used four-barrel carburetor in General Motors' history. It was a stock GM carburetor for years on the company's performance cars, including the Corvette. I believe I recall some Pontiacs using aluminum faced intake valves to promote better sealing. It drilled throttle plate modification quadrajet apt was drilling ports and drill. In 1982, 'Cross-Fire' throttle body injection ended Corvette's carburetor era. EFI for Quadrajet Users--Sniper Quadrajet EFI System. Quadrajet - APT screw turned out 1. The number starts with either "70…" or "170…". PHOTO 3 The Quadrajet is considered a three-piece design: air horn, float bowl and throttle body. Re: Quadrajet 4mv Part Throttle Lean Post by Matt Gruber » Sat Sep 22, 2012 10:37 am Rebuilt qjets are often messed up. Once in a while a front plug shows leakage. The kits contain 16 bushings, 1 drill bit reamer, 4 retaining screws and an instruction sheet. Throttle shafts are sealed to prevent leakage. If you have on of the countless thousands of Chevrolet, Buick, Oldsmobile, or Pontiac vehicles built between 1965 and 1979 with the Rochester Quadrajet carburetor, and if your situation necessitates that you stick with a Quadrajet format, then your EFI System has arrived. The most common undrilled hole is the power piston vacuum passage in the throttle plate on 1975 ÔÇô 1980 Q-Jets. 87 318 auto w/rochester quadrajet Issue is the throttle lever gets stuck causing the throttle lever to slip past the end and sticking. The quadrajet s a fine carb with very small primaries and very large secondaries. Results in: Poor cold-running characteristics, sticking choke, engine stalling when cold, engine not coming down off fast idle unless gas pedal . Search: Quadrajet Float Sticking. When the motor is warm it hesitates but barely. 0 liter 307 Oldsmobile engine has a hot air choke. Hey guys, I'm moving this post from an old thread about other issues. QUADRAJET 101: Author Topic: QUADRAJET 101: (Read 12692 times) As far as the throttle sticking, dow you feel the linkage bind as you . The gauge needle, however, was somewhat erratic so I concluded that this was due to a discrepancy of the mixture screws. The wear problem with the Quadrajet carburetors was due to the steel throttle shaft wearing into the aluminum housing of the throttle body assembly. ALLDATA -- Jim Grant's Tech Tips -- '86 Chevy Truck, Sticking Accelerator. 1) Look for dirt in pump nozzles, swollen cup from bad gas, or check ball missing or stuck. The first step you need to take to change the throttle cable from the carburetor is to turn off the fuel valve on the fuel tank. This is just one of the solutions for you. Two common problems with rebuilt Quadrajets are sticking power pistons and poor fuel-delivery from the accelerator pump. These are very small passages and get clogged easily with ethanol residue. Bronze bushings; Eliminates common problems such as; vacuum leaks, binding or sticking throttle; Includes reamer; Instructions included. When the secondary throttle plates are opened beyond this point, turbulence in the secondary side actually decreases airflow. You can make one by using the base gasket as a template, drill a piece of 5/8 or thicker plywood to put 4 5/16 bolts thru, countersink the heads so they sit flush. The Zako-ATS is a precision crafted tool manufactured in Alberta, Canada. Cleaned and idle mixture adjusted good too. With the throttle at full open, the secondaries should be almost straight up & down. If the date code under the number is 4 numbers "1938" like above it was produced by Rochester. Only gained a couple HG so it now bounces around between 10-12 HG. then the power valve is probably stuck up or mis-adjusted. 7liter 350 Chevrolet engine has an electric choke. Check for loose throttle plate screws first. Including DualJet, Varajet, Two-Jet (2G, 2GC, 2GV), MonoJet, Model B, BC and BV, Holley 2245, Carter BBD carbs and more. org File Type PDF Trouble Shooting Guide For Quadrajet Trouble Shooting Guide For Quadrajet Yeah, reviewing a ebook trouble shooting guide for quadrajet could add your near contacts listings. A long history there, thanks for sticking with me. Buick 1966-76, Cadillac 1967-74, Checker Motors 1967. Shown here is a 1966 Quadrajet, carburetor number 7026260. The Edelbrock "Performer" and Carter "AFB" run $225 or so. Blipping it would usually drop . Once properly set, this will start like fuel injection. The issue I'm having now is when you stab the throttle it will kill the motor. make sure the shaft is not loose in the throttleplate and the throttle opens smoothly. The Quadrajet has 1 3/32- or 1 7/32-inch primary throttle bores with either 750 or 800 cfm. However, and drive flats are four shallow, so care data be service to make sure does the valve remains fully seated. So after about 3000 miles the idle started hanging at times, 1500-2300 RPM. I'm having a problem with bogging when the engine is cold. Rochester's timeless Quadrajet four-barrel carburetor can perform The throttle position sensor provides throttle position feedback to . First I loosened the carb and shifted it around to make sure the throttle plates weren't hanging on the gasket. Its idling a little high and when I press the throttle it wants to stick at its highest RPMs like the spring on the pump cup is stronger than the return . I used 1½" bolts for the rear of the carb and 1¼" bolts for the front. Brass Float Rochester Quadrajet Carburetor 4M 4MC 4MV 1965 - 76 Select Carbs. Buy carburetor you're referring to is likely GM's well loved and hated Quadrajet. This is what I'm running on top of the Edelbrock Performer intake manifold for my 252/4. 350 with HEI and quadrajet, Stumble when full throttle Discussion in ' The Hokey Ass Message Board ' started by socal_wrench , Dec 24, 2005. Having runaway revs on warmup, sometimes persistent. About Quadrajet Sticking Float. STAGE 2 - All features of Stage 1 carbs plus fully recalibrated idle, off idle, main, accelerator pump and high speed circuits. 1976 Corvette Stingray: Restore, Repair, Detail: Quadrajet. The engine is idling to high (1000 RPM or so in drive) when warm with the choke open. The air horn is the top section of the Quadrajet has many components to work with. The Rochester Quadrajet is a modern design, and uses some very forward-thinking features such as a central float bowl with one float, vacuum-operated metering rods for power enrichment, an air-door controlled secondary, and no gaskets. Pic #1: Throttle side - note that, with the fast-idle cam set (cold engine, choke ON) my throttle is held slightly open. 1986-1988 Buick Pontiac Olds Cadillac with 5. For rebuilding a quadrajet carburetors produced in quadrajets are crucial for a significant rotating it should have your engine modifications, clutch and comments to. Re: Quadrajet accelerator pump problem. When the throttle gets stuck in an open position than your vehicle will receive too much air and cause it to have a high or fluctuating idle. Are you completely depressing the Pedal to kick it off. It should kick down when tapping the throttle, but it remains at 1000 rpms until I either back off the high idle screw or manually turn the. If you feather your foot into it, its fine. The quadrajet carburetor model type carb solvent can use things. The early carbs all have a factory spec of ¼". Sorry about the confusion I haven't worked on a quadrajet in a while. Indigo Zap Pony Indigo Zap PonyIndigo Zap Pony 2020 19:23 ссылка 8. The air horn can be sanded or machined flat to re-conform to the main body. 7l 350 and had to rebuild the quadrajet carb im having a problem where i cant get the idle speed to . Trying to get things setup per the initial setup instructions: "If the value is 0 the blades need to be closed until it reads between 2-10%, if the value is higher than 10% the blades need to be opened. 21 - Throttle position sensor/high Check for a sticking or maladjusted TPS plunger. The Quadrajet is a progressive four-barrel design with an air valve actuated secondary circuit. If you want a new carb and won't save up for a Q-Jet, then you might be okay with the Carter # 9504, (elec. We disassembled, cleaned and put it back together and it will now run pretty well. Viola, you have a rebuilding stand. « Reply #2 on: May 08, 2013, 11:35:56 PM ». Just may need the throttle cable adjusted so that it opens the throttle blades all the way and at the same time kicking you high idle off. Also remove the overflow in the hose. The “M” after that, is a style/model type. 350 with HEI and quadrajet, Stumble when full throttle. These lead plugs can leak and/or fall out. then i found if you boil a carb for about 15. Its almost like engine vacuum is . In simplicity the Rochester Quadrajet is made up of many parts but it all resides in 3 main castings. I've seen this problem so many times now, that I'm sure there are a lot of cars out there suffering this problem. The car runs ok once the secondaries kick in and it starts and idles and cruises great under light and medium throttle. QuadraJet Idle Problem from corvetteforum. Also a throttle position sensor. I have pulled apart the carb and the throttle plate and shaft move freely and I don't feel any obvious binding. If you look down and your TPS is 2% then either your throttle is stuck slightly open (which itself will cause the idle-up) or RFI riding on the TPS signal has caused the ECU to see the throttle as open and, as a result, open the IAC to the hold position. These numbers can be found on the side of the carb main body next to the throttle lever , 1965 to early 1968 was a round disc 1968 and later ones where stamped into the body on quadrajets. The problem is as follows: (1) After the engine is switched off, heat from the engine heats the fuel in the fuel line. neither is the shaft wear, as the teflon contacts a section of the shaft and base that never has touched each other, so, there would be NO WEAR in those. Sniper QuadraJet, can't set IAC Position %. Quadrajet isn't clogged and make sure the fuel pump is suppling adequate fuel pressure and flow. When you let off your throttle, the needle lowers into the main jet circuit, cutting off fuel flow as it goes down. Troubleshooting a Quadrajet Carburetor | It Still Runs Trouble Shooting Guide For Quadrajet Troubleshooting a Quadrajet Carburetor by Don Bowman. If the fuel line is cracked or has become old then you will need to replace it so that there will be no leaks. 201102 Quadrajet Bushing Kit. For high fast idle and slight sticking unscrew fastidle screw. Initial idle speed can be obtained by seating the primary throttle plates and then turning the idle speed. The car runs ok once the secondaries kick in and it starts . The teflon BECOMES not only the seal, but the BUSHING, and it IS NO STICK, so, binding of the shaft isn't an issue. possible Vacuum leak – Use spray carburetor. Saw a Ford one time that stuck WOT, because the engine ground wire broke and the current was using the accelerator cable as a (poor) ground, melting the rubber case and causing the cable to stick. Speeding the idle up prevents the cold engine from stalling. The late carbs have much lower specs at about. The initial adjustment for idle mixture screws on most Q-jets, for example, should be lightly seated and then backed out three turns. 6769 Camaro Throttle Rod With Swivel Universal Rochester 4bbl Quadrajet 13. I had a problem with that on my '66 The piston was stuck, and after torching it for a long time, I managed to get it out, but the rubber that held it together had melted. Joined Oct 29, 2001 · 828 Posts. as the apt screw is behind the tamper proof plug in the front of the base plate. I have a SMI quadrajet that is 5 months old. Throttle body cleaner is formulated to help break down carbon and other fuel-related deposits on a throttle body. To be able to adjust the idle mixture but still single. The idle adjust screw is backed all the way out and the mixture screws are adjusted. If it does not get moved out of the way by the choke fully opening - no secondaries ever. When i release it from higher rpms, it will come back down to idle real slow sort of like pouring syrup on pancakes. Jump to Latest Follow This is one reason throttle body injection is not so much better than a carb setup in some respects, and worse in others. inconsistent idle speeds and binding or sticking throttle. Specifications about my 750 CFM Quadrajet carburetor:. All carbs must have the throttle plates open slightly to be able to adjust the idle mixture. Park/neutral or in drive -> full throttle and it stumbles and strikes on exhaust when I lift pedal up. Quadrajet Adjustments The Quadrajet has a number of critical adjustments that make it perform better. Sticking Secondary Throttle Blades. Hey all, I have a 318 LA with a Edelbrock 4bbl intake and Rochester quadrajet. Most performance enthusiasts shun the Quadrajet as a stock carburettor laden with useless emissions controls. I'm totally new to this, but I'm planning to purchase a Sniper soon and I'm curious if it's worth paying extra for the QuadraJet Sniper vs just purchasing a regular 4-barrel Sniper with a spread-bore adapter. the secondary throttle is a constant-depression design, airflow specifications aren't as critical on Quadrajets as on conventional carburetors. Check; lead plugs, cracked, warped castings, wrong, plugged, ripped misaligned gasket(s) also the throttle plate bores can get worn. It is basically a cover for the components within the float bowl and has the four upper throttle plates and two shafts that are controlled. They are not designed to be open straight up & down, like the primaries are, at full throttle. I run a pro built qjet on my big block and it runs good and has great manners. The quadrajet is a really good carb if set up right. QUADRAJET 101: « previous next As far as the throttle sticking, dow you feel the linkage bind as you open and close the throttle shaft by hand? i don't really feel any binding. Quadrajet Tech By Randy Frazier. Having a problem re-assembling a Rochester quadrajet off a 1979 Chevy c10 400 4x4. Duplicated to original quadrajet gasoline specifications including throttle linkage. The linkage operates a fast-idle cam that keeps the throttle from closing tight. Most importantly is proper ignition timing. The next letter, V, C, or E stands for the type of the choke's thermostatic coil. If the carb is a Q-Jet manufactured under license by Carter, it will sometimes have the carb number stamped into a foil circle on the driver's side of the bowl just above the primary throttle shaft. This results in vacuum leaks and throttle plate mis-alignment. Using bronze bushings, the kit eliminates common problems such as vacuum leaks, inconsistent idle speeds and binding or sticking throttle. 0 liter 307 engine has a Hot air choke. Or carpet is in the way near the foot feed. Dual Throttle Return Spring Carb Bracket Holley Edelbrock. This is vital since the sensor does the role of giving feedback to your electronic controller unit (ECU), which is also crucial for managing fuel delivery and managing the auto transmission shift controller. have a quadrajet on a small block. This requires the throttle to be pressed slowly to the floor once to allow the choke plate to close, and needs to be done prior to cranking the engine over. First what exactly is the problem (sticky usually means sticking at high idle) The gasket with the 4 holes is the correct one But it could be for a carb with smaller bores You should be able to look down the bores with a strong light and see if there is any interference at the gasket before removing. Discussion in 'The Hokey Ass Message Board' started by socal_wrench, Dec 24, 2005. This heats the choke stat when the engine is running, so that when you "blip" the throttle after some warm up time, the choke comes off. Quadrajet secondary air valves are sticking open. check and adjust fast idle cam for free movement. 24 - Mixture control solenoid A fault in this circuit should be indicated only when the vehicle is in motion. February 17, 2016 at 10:18 pm #851981. Pontiac and Chevrolet rebuilt carburetor E4ME 1986-1987 GM passenger car with 5. Always had an issue with the throttle hanging up when I . behind the choke assembly and down to where I think its stickingbut its really . Brass Replacement for Rochester 7029854, 7033752, 7034399, 7034454, 7046301. I have #73 jets and #43 rods with. To adjust the airvalve tension you need to adjust the spring on the starbord side of the secondary valve. 201102 Quadrajet Bushing Kit The JET throttle shaft bushing kits for Rochester and Holley carburetors will restore your throttle valve assembly to better than new tolerances. At some point someone used a 73 Chevy Camaro casting with a 68 or 69 top horn assembly. What are signs of a bad Throttle Position Sensor? Acceleration issues: A bad TPS may cause all sorts of power issues. This is a 'common' issue on Quadrajet carbs, and there are an epoxy kit that is used to repair. Looking for a mechanic who knows how to work on a 455 ci V8 (quadrajet) Electra 225 coupe. Perhaps it was a profeshional rebuilder / remanufacture that has used all the correct jet, rod, oriface, springs, & adjustments for the Cadillac. Alcohol Resistant Accelerator Pump Plunger Quadrajet. Re: Having trouble with a Quadrajet. The quadrajet version for 68-73 Chevy & Cadillac seem very similar. When the engine looses vacuum the dashpot moves out. This hole was drilled in 2 operations: halfway through the throttle plate from the top, and then at a 45-degree angle up from the bottom to intersect the top hole. Last, the metering rod piston can stick in its bore, causing a lean air/fuel condition. (hard acceleration) As the vacuum recovers the dashpot pulls the throttle linkage shut. The throttle return spring is attached to the throttle cable or it can be attached to the throttle body or carburetor. Decreasing tension on it has 2 main benefits. As the engine warms and you move the throttle the choke will step down the idle speed. A Mixture Control Solenoid in the float bowl controls metering to the idle and main systems. Fuel Line comes in from the side of the carb. New Sniper QuadraJet & HyperSpark install on a SBC 305, replacing the old QuadraJet carburetor. To start this off, I just wanted to tell a little bit about the stock Q-jet that came on my truck (1985 C-10). Provides improved idle quality, instant throttle response and maximum torque and hp. Changed carb top to a '69 Pontiac 428 top, with visibly smaller idle air bleeds. As you will see later, the cutting flutes sticking out at the end are chucked into the drill or drill press. This will mess up your idle and your idle mixture capability. This basic design was typical of very early production. injection pump is simpler -than let's say a Rochester Quadrajet carburetor. Visit our site for Quadrajet parts. It is known for its high performance and reliability. But before starting on the choke setup, it's important to remember a few other tuning parameters. The original throttle body had a broken off idle mixture screw in it, and was unremovable, along with a lot of throttle slop. Sticky throttle kickdown linkage, Rochester Quadrajet. With the threads now clean, the springs from the old mixture screws are placed on the new screws, and they are gently bottomed and then backed out 3 turns each as per the factory service manual. The first thing that comes to mind is the accelerator pump check ball hung up. Timed to ~6 BTDC with vacuum advance. If you see dirt in the bottom of the fuel bowl, rebuild the carburetor, clean the fuel lines & the gas tank. Make sure the butterflies on the bottom aren't sticking open. March 2022, Quadrajet rebuilds about 20 weeks, Quadrajet rebuild with re-color and plating about 25 weeks. the secondary throttle is a constant-depression design, airflow specifications aren’t as critical on Quadrajets as on conventional carburetors. it bends a wire up that actually sticks up above the surface of the base plate. On road, it stumbles second or two like it shuts off, then car accelerates but futututu and poor performance. As engine warms, the choke opens wider, the cam moves off fast idle and the idle speed drops. Wanted to see if my thinking is correct. It is a good carburetor for fuel economy and still has stellar performance when required. My First Board Book Numbers |My First Board B Lumber Tycoon 2 Script 2020 Pastebin; Lumber Tycoon 2 Script 2020 Pastebin. How To Clean the Throttle Body. There is a moment of quiet followed by a large increase in exhaust volume, sometimes described as a 'booming' noise. Re: 1968 Quadrajet Dashpot? Postby Twilight Fenrir » Sun Jan 15, 2012 10:39 pm. Main metering jet may be the wrong size. JET Performance 201102 JET Quadrajet Bushing Service Kits. Dirt in the system – take the top off the carburetor. Quadrajet Throttle body Identification; I am hoping that I can use this throttle body, or else I am kind of stuck. I have a 318 LA with a Edelbrock 4bbl intake and Rochester quadrajet. Also has a 2 wire Blue plug mixture control solenoid sticking up through the top of the carb on the left hand side. How to remove the Throttle Cable from the Carburetor. 2) It "diesels on' sometimes after i shut it off, which probably has something to do with the idle-stop solenoid thing (fig. When the engine is started, the throttle should be tapped just a little to allow the choke to snap shut. The throttle body is aluminum to reduce ove:rall weight and to improve heat distribution, plus there is a thick throttle body to bowl insulator gasket to keep excessive heat from the float bowl causing fuel percolation. Check for vacuum leaks, are the throttle shaft bushings worn out is there lots of play in the throttle shafts. set choke to closed setting,release throttle, tighten ret ring. A Quadrajet carburettor car is often distinguishable from other cars by the sound of the engine as the secondaries open. Quadrajet Carb is reassembled with new float, choke pull-off and bronze bushed throttle shafts. The reason it seems to work with the engine running is possibly due to the slight vacuum in the area so atmospheric pressure will act on the fuel level in an attempt to equalize. So, a 4M is a Quadrajet, and a 2M is a two-barrel Dualjet. There is also a secondary lockout that is operated by the choke. The float in the carburetor regulates the amount of fuel or gasoline which resides in the reservoir. When we dug into it last week, the float was stuck on the carb. It worked well up until recently. 1971 Buick Skylark - Seeking help. make sure the little 5/8 filter inside the little blocky housing on the front of the. Quadrajet Troubleshooting Rough Idle This can be caused by several things, but there is one item often missed by the rebuilder and that is the idle tube. This guide describes an easy do-it-yourself repair procedure I learned from Dave Ray (IgnitionMan / HEI451) on an auto repair message board. When it's broken or wearing out, the throttle may stick wide open, causing a potentially dangerous situation. Whether you drive a Kia or a 10,000 horse power Top Fuel Dragster, having a fully functional throttle return spring can save your life. If the vacuum reading is fluctuating or erratic, it is usually from sticking valves or misfires. I have an Oldsmobile 455 with the QuadraJet spread-bore manifold. This has been going on for a while now. Last, always make sure that the choke valve lockout is allowing the secondary throttle plates to open. Rochester Quadrajet M4MC Carburetor Kit K4258 Out of Stock BUICK 1977-87, CHEVROLET 1987, CHEV/GMC TRUCK 1977-78, OLDSMOBILE 1975-87, PONTIAC 1977-87 Accelerator pump cup = 21/32". Rebuilt carburetor 4bbl Rochester Quadra jet E4MC. (3) The check valve prevents the fuel backing up through the fuel pump. Although most Quadrajet float levels are set at 3/8", the specification can vary from 5/16" to 1/2". The next letter, V, C, or E stands for the type of the choke’s thermostatic coil. The reservoir of the carburetor is where the fuel is sucked into the intake manifold. On November 16, 2016, I had enough of chokeless cold starts and reinstalled the Quadrajet. Comments: Different year Q-Jets have different float level requirements. 068"- the metering end is gone, for all practical purposes. Hey bud you drill one in throttle plates drilled and! The fuel system in my wagon is a somewhat overkill setup! Some quadrajet throttle plates drilled hole, modifications is to adjust transition hole it is imperative that. I just installed a new qjet on my 350 and it bogs when coming off idle. look in the carb and open the throttle w/ your hand. The truck is a 1970 C10 with a 350 ci motor and a 4 barrel rochester quadrajet. possible Vacuum leak - Use spray carburetor. Issue #1 - takes a bit of cranking to get it started after it's been sitting. No detectable vacuum leaks and the throttle linkage is loose at idle. Rebuilt carburetor 4bbl Rochester Quadra jet E4MC computerized carburetor. When the engine is warm, less fuel is required. It is not the cable as it does this with it unhooked. Rochester Quadrajet Carburetor Brass Tube 17-91. Anyway don't panic if you did it with the old stuff just remember if you start having sticking issues in the future. 2) Float level setting very low. Have a 4160, 3310-6 list on a happy lil 327. Early Rochester four barrels were a “G” series. The Dashpot pulls the throttle linkage shut so disconnecting it would cause the problem all the time. How's the throttle return spring? ------------------ Joel T/C#980 1968 SS396 CHEVELLE If at first you don't succeed, skydiving is not for you W wolfehunter Registered Joined Oct 29, 2001. trucks have dual capacity accelerator pumps. But heres the rub, the idle will not go down very low and I can literally. Quadrajet Choke Linkage Diagram - schematron. Quadrajet 17085212 just rebuilt with SR kit and new primary shaft bushings. take the throttle plate off the carb and make sure the throttle blades are not loose and close completely. First thing to do is remove the throttle cable from carburetor and see if it has enough slack to allow the throttle to close all the way. The Sniper EFI Quadrajet™ retains the same great features as the 4150 Sniper EFI version such as; four 100lb/hr Injectors, built in timing control, a 3. Every factory Rochester Quadrajet flows a minimum 750 cfm, and there were a few units rated at 800 cfm. There are some blemishes on this finish, see pics for detail. The Quadrajet can withstand some warping and continue to work fine. but you are correct that he may need to set the idle speed a little higher. I have a 1968 Firebird 400 with a Quadrajet carb. As a service to Dallas Area Pontiac Association members and in the spirit of the Pontiac Southern Nationals, this article has been prepared with the hope that it will help enthusiasts optimize their Quadrajet carbs for performance. the accelerator pump piston passes through the top of the carb body. Throttle shafts can be bored and bushings installed by a reputable carb shop if that's the problem. com is providing this video about setting the Quadrajet 4 barrel secondary opening setting. you have seen that if you have done any 65 to 75 quadrajets. First, the end of the ream that would normally be chucked in the drill is inserted as though it were the throttle shaft, acting as a pilot. The carb runs fine other than the cold high idle will not come off the high idle when engine warms up. In and after about 1968, stamped numbers were used for Quadrajet Carburetor identification. Using the supplied bronze bushings, they eliminate common vacuum leak problems, inconsistent idle speeds, and binding or sticking throttle. Rochester Quadrajet brass tube. This value is itself enough to raise the idle a bit. Tuning for Performance with your Computer-Controlled Quadrajet. The Quadrajet has an accelerator pump system, which increases fuel flow during acceleration, resulting in improved engine response time. Joined: Mar 3, 2001 the vac advance and make sure the diaphram isn't broken by sucking on it with a piece of hose if the advance moves stick your tounge in the hose and see if it stays put. ninjagin February 19, 2022, 1:08am #1. Much smaller than the Main Jet and typically has no effect beyond approximately 1/4 throttle. Changed throttle plates to undrilled ones, that was just making it worse. Were the throttle shaft bushings replaced during the rebuild? If the . The old one did this as well, so when I removed the old carb I checked the . In a sense this was a temporary bridge between carburetion, throttle body injection, and port injection. I vacuum tuned the idle mix screws to highest vacuum. Find many great new & used options and get the best deals for Dual Throttle Return Spring Carb Bracket Holley Edelbrock Carter Demon Quadrajet at the best online prices at eBay! Free shipping for many products!. Quadrajet History and Design. I am not sure why the coating is there even- Lubrication i think because a throttle body doesnt have the fuel flowing over it like a carbs blades do. Needle Clip: This is the small circular clip that is used to adjust the needle position. In addition to all of these great tried and true features, the Sniper EFI. Usually, whenever there is an issue with the throttle position sensor, you are likely to have a problem with how your engine functions. It has an extremely rich, eye burning idle, with the idle mixture screws having absolutely no effect on vacuum readings or idle speed(but it does seem to idle smoother with them turned all the way in). For use in Rochester Quadrajet models with APT located in the Throtle Body. When functioning properly, the full depression of the accelerator pedal will release the choke spring tension being held by the fast-idle cam and screw, while also providing a shot of fuel. I have a SMI quadrajet that has worked great for 5 months. These differ from the early Quadrajet with the addition of a throttle position sensor, a metering control solenoid and information fed to and from the vehicle's computer, sometimes referred to as a feedback carburetor. MAKE YEAR MODEL CARB NUM PRIMARY JET SECONDARY JET METERING ROD SIZE BUICK 1966-67 400″ 6. The throttle temperature can vary by processor and BIOS settings. Setting up an early carb to the late spec is a common mistake, and will cause performance problems. I need to figure out the air bleeds for this carb for primary. We are not responsible for USPS or UPS service. Given the low miles, a worn out throttle shaft seems a bit unlikely. The throttle returns fine when truck is not running but with it . Check the choke assy to see if it's sticking. 1981-1985 Buick Pontiac Olds passenger cars with 5. Yes, I should have adjusted the idle. Discussion Starter · #1 · Mar 25, 2002 I was approaching a turn and got off the throttle but she was screaming even though the pedal came back up off the floor! I pushed in the clutch as I panicked and as the. Hey guys I just rebuilt my quadrajet on my 83 GMC C2500, I started with the idle mixture screws at 1. How to Properly Disassemble a Rochester Quadrajet Carburetor. 3) Secondary air valve set wrong. Check carefully that there's no way the linkage can like go over center and stick the throttle wide open. Always a bummer when that happens. Crimped on metal retainer prevents the shaft from pulling out and highest quality pump cup that stands up to todays new fuels. 5”full color touchscreen and much more! The throttle body will support up to 500 horsepower naturally aspirated. The choke mechanism on a quadrajet needs to be adjusted and work properly for the engine to run well at low speeds. In the last couple of weeks the throttle (quadrajet) has started . load if they get stuck open and I throttle back, will the engine will run poorly?. i tryed basic cleaners without sucess. A bad or sticking carburetor float causes engine problems. the idle is terrible, choke on or off. What is Quadrajet? The Quadrajet is a four-barrel carburetor that Rochester made from 1963 to 1985. The idle mixture screws are located in the base plate for superior idle quality. Your engine may start up but it will have little to no power and it causes it to shut off. Only under 3000rpm and heavy throttle does it stumble. Initial idle speed can be obtained by seating the primary throttle plates and then turning the idle speed . my carb was so gummed up i couldn't move the slide or remove the jets. It has been proven you can modify the Quadrajet to flow in excess of 1,000 cfm. My 4 barrel Rochester Quadrajet keeps flooding have a 1984 Chevy caprice want stay running and throttle is sticking what is the problem. Quick ref, while choke in open position and throttle on stop screw. 69 Toronado Quadrajet Secondaries Not Opening Post by NicolasB » Mon May 25, 2020 2:16 am Hey guys, so after inspecting the engine a bit more after fixing the stalling issue, I noticed that the secondaries on the carburetor do not open, even when the throttle is all the way down (I did let the car warm up). In addition, some late-model Quadrajets were configured to only partially open the air valves or secondary throttle plates on small-displacement engines such as the Chevrolet 305 cubic-inch V8 engine. When the spring is damaged or wears out over a period of time, the throttle's ability to close shut is compromised. Besides, being grade 8 hardware, the Zinc yellow-Chromate finish matches the rest of. The other long-arm holder held it fine, but wouldn’t clear the vacuum tubes sticking out of the throttle body. Open the secondary air valve plate, and look down in the rear of the carb. As background I have just got the car on the road a couple of months ago. It is a good carburetor for up to close to 400 horsepower. The secondary throttle plates should open to a position where the angle of the throttle plates points and aligns towards the lower edge of the secondary airflow baffle located in the secondary venturi bore. The 4G 4-barrel, however, was used on other Chevrolet V-8 applications, while radical, high-performance applications retained the Holley 4-barrel. Need someone to confirm my thoughts. The cam also helps you start a flooded engine. Watch for certain signs and symptoms if you suspect the carburetor float. This will cause a "wedging action" if the throttle shaft or a throttle plate is flopping around loose, making the throttle plate touch the edge of it's bore prior to closing all the way down to idle. Signs and Symptoms of a Sticking Carburetor Float. It opens up when airflow through the secondaries demands it. I think Ive got the throttle linkages on thethe right side … read more. 6869 Camaro Nova 327 350 Rochester 4 Bbl Carb Quadrajet Throttle Rod W Swivel. We offer today's top-selling car carburetors at savings up to 90% and discounts on ss super carb, carburetor carb open, size main carburetor, quick fuel carb, fitting fuel carburetor, ford chevy carburetor, carburetor edelbrock avs, rochester rods rod, screw aed holley, stack stacks weber, carburetor lever throttle, stick non base, ported carb, stick blue holley, aed fuel bowl, pontiac body. As soon as the engine starts, the vacuum servo receives . To adjust, open throttle so choke butterfly closes (when cold), connect a hand vacuum pump to vacuum choke pull off and pump it up both verifying the diaphragm is leak free and to cause the pull off to pull the linkage to the open/running position, and use a 1/4" drill bit to check the gap between the partially open choke butterfly and inside. Having trouble with a Quadrajet. I am rebuilding an old Quadrajet that came off my 68 Deville. Re: Throttle Sticking 02-25-03 03:58 PM - Post# 184928 In response to I just fixed this same problem on my '79 C20. "Computer controlled carbs, E4M, differ from the original M4M in that the primaries have a feature for optimum A/F mixture control during all ranges of engine operation. i bet you wondered why the early quadrajets have a pin that sticks out the …. After a few tankfuls of gas, I found that, even though I now have a working choke, it was difficult to start in cold weather and it has noticeable lean surge at part throttle. (2) The expanding fuel (increased volatility) creates pressure in the fuel line from the pump to the carburetor. Rebuilt/restored 800cfm Quadrajet #7042240 1972 Buick 455 Quadrajet Rebuilt with throttle shaft bushings, new float, secondary cam, fuel filter, epoxied well plugs, blue ethanol resistant accellerator pump cup! 73jets 44B rods DA secondary rods refinished in Zinc Chromate. My friend who drove the car said that the linkage is loosen (see red arrow on the pic bellow). Pilot Jet: This is second jet in your carb. This is the tube (there are two) that stick out of the bottom of the float bowl top. The effect was the same as sticking your finger in a stream of water. it runs well above 1000 rpm's but idles terrible or not at all. Troubleshooting a Quadrajet Carburetor. The design is for the secondary throttle blades to open with the throttle linkage(at 3/4-full throttle), and the air valve is controlled by the amount of air rushing past them with the throttle blades openlike a variable venturi effect. Loose throttle shafts due to worn baseplate shaft bores are a common problem on high mileage QuadraJet carburetors. When the engine is cold, more fuel is needed for transition from idle to part-throttle. The shaft has a smaller shaft sticking through it the pivot catches. GM used the quadrajet on millions of vehicles throughout the years with very few problems. I cut a new one out of a flat rubber washer, and it seems to work. Rochester Quadrajet 4 Barrel Secondary Setting. Like the base plate, a common auto store kit doesn't have any parts for this, but it sure needs attention for the Quadrajet to perform for you. Setting the Air Valve (AV) tension on your Camaro or Firebird. What happens is that one of the vacuum passages on the bottom of the carb will actually "hang over" the outer edge of the base gasket - very slightly - giving you an almost undetectable vacuum leak directly into the primary side throttle. I plan on totally recalibrating it for a 220ish duration cam. The only way to adjust the idle speed is with the throttle adjustment screw. Holley Sniper Quadrajet EFI System.