These are just a few ideas, but bottom line is that too much fuel is getting into the float bowl. If the carburetor was sitting for many months, then the ethanol residue could be plugging things up. Inspect the choke system while the engine is cold. What I was referring to pickup tubes are call the main well air bleed tubes (2 inside tubes ) and secondary accelerating well tubes( the 2 outside tubes) fig. I think this is what I need to do. Compatible with all Chevy/GMC trucks and cars 1966 thru 1973 Available for 327, 350, 396, 400, 402 or 454 Engines Bolts on to any Quadrajet/Spread bore GM style intake manifold Too much fuel boils down to getting too much in the float bowl. Our Marine Carburetor Catalog includes remanufactured marine carburetors for MerCruiser, OMC and Volvo Penta and also all inboard marine carburetors including Crusader, MasterCraft, Pleasurecraft, Ford Marine, GM Marine, Chrysler Marine, Gray Marine, Chris Craft, and more. Today’s gas has little lubrication. This causes the engine to run poorly. 1904 Carburetor Info Page. We stock complete accelerator pumps, replaceable cups and springs. When getting a carb from another vehicle, whenever possible, get the factory cable bracket. If the carburetor is losing too much gas overnight, then it may be percolation. This test is performed to ensure that all idle circuits and other carburetor functions are working properly. I rebuilt it using a kit I ordered from you. And yet another troubleshooting guide here. It is a good carburetor for up to close to 400 horsepower. NOTE: Do not apply any pressure to the needle when adjusting the float. However, it's easy to flood the engine this way. Look for any fuel restriction – check for kinks in the fuel line. Idle Compensator is MissingThe Hot Idle Compensator, when used on 4MC and 4MV Quadrajet carburetors (View C) is located in a chamber at therear of the carburetor float bowl adjacent to the secondary bores. New pumps are always suspect because they come from China and they don’t seem to care about specifications very much yet. My question is should I have the secondary accelerating well tubes and if I do is that the right part # ? Rochester Quadrajet Carburetor Cadillac 472, refurbished. If the RPM changes then you found your problem. Make sure the jets are not loose, or plugged. The Quadrajet uses many moving parts, unlike most carburetors. The fuel is too high in the float bowl and is being sucked out of the jets into the engine, thereby flooding the engine. Ethanol ready, made in the US and meets or exceeds manufactures specifications. The carburetor is simply puking out too much fuel. Many times after rebuilding a carburetor and after re-starting the engine, crud from the tank and the fuel lines will rush up to the carburetor and into the needle & seat causing it to stick open. However, I read a post online that said the fuel at the thottlebody should already be atomized, and should therefore not leak out the linkage,and that would indicate that the carb is flooding due to the float not being adjusted properly. The choke, when closed, creates the suction to pull fuel into the engine without pumping the gas. My question is, how is the gas getting out of the float bowl, and how do you fix it? Using a small screwdriver and starting on the driver's side, adjust the screw in until the RPM starts to drop. Using a solid gasket on a carburetor designed for the slotted gasket WILL result in hot idle issues. Free Carburetor Repair Manuals Mikes Carburetor Parts. Polish the pump well with crocus cloth, or 2000+ sand paper. Use thin wire to clean out the passages completely. Is the fast idle sitting on the higher step of the cam. The throttle keeps it from closing as long as it is not disturbed. And if so, do you carry the kit? If not, the servo must be replaced because it operates with a rubber bladder inside and is leaking. I reinstalled the carb and I’m having the same issue of fuel leaking from the throttle body linkages. A: There are two things that can cause a Quadrajet to leak. Take the carburetor apart and wash out the needle & seat and try again. There could also be a leak at the intake manifold. As mentioned above make sure the choke valve is closing. Apply a couple of dabs of white lithium grease. Copyright 2021 Leaf Group Ltd. / Leaf Group Media. Quadrajet bbl.) This is a sign of flooding. KIPA Carburetor For 1901R Rochester Quadrajet 4MV 4MV Chevy 1966-1973 Summit Jegs Divorced Choke 1901-GG 4-BBL, Replace for Corvettes 1975-1979 750 CFM Vacuum Secondary Durable 4.0 out of 5 stars 9 $312.75 $ 312 . QuadraJets are only slammed by people who know nothing about them. Ethanol blends in gasoline today are responsible for many fuel system issues and carburetor failures on older Corvettes. The pump passage way to the main discharge may be plugged. Rochester Quadrajet accelerator pump catalog. On all carburetors, the vacuum created as air is moved into the engine sucks the fuel out of the passages in the carburetor. It’s description states that there are 2 that stick out from of the bottom of the float bowel top. Even if you're using an aftermarket intake, it might come in handy for making up your own bracket. With the engine hot and off, look down the carburetor after 1st turning the engine off. Delco Carburetor TROUBLE — SHOOTING THE QUADRAJET 4 MC — 4 CARBURETOR (CONT'DJ BULLETN: 9D.ST DATE: AFTER goas wo, 131.132M, ex, GENERAL MOTORS CORR IN . All carburetors are installed on our test engine prior to shipping. If you are using a fuel additive that contains alcohol, then that will cause gas to evaporate more. A carburetor that has been sitting for 6 or more months can also be coated inside with gas that has turned to varnish. Did you put the fiber washer where the seat screws into the float bowl. A whistle with air will indicate a clean passage. The Quadrajet became an instant success. Some chemicals added to the fuel, or left in the carburetor can cause this. Do the same to the other side and then repeat the process one more time. Wiping with mineral spirits can help. Some will open just slightly so it doesn’t choke out. You can get your C3 Corvette—or any other carbureted vehicle, … The float will heat up inside and if there is a hole, air will bubble out. Move the float up and down by hand – Do you feel anything catching? and customer satisfaction. Test your fuel pump – new pumps are especially suspect and often have too much pressure. This carburetor was made by Rochester , The Rochester Products Division of General Motors was located in Rochester New York and built carburetors for GM vehicles since 1949 . It may take a few seconds of cranking to fill the carburetor (if low). The Quadrajet is a progressive four-barrel design with an air valve actuated secondary circuit. Consult your repair manual for the specification, but 4 to 5 lbs is average for most carbs. Carburetor is flooding.Gas is running out of the top, or you get a strong gas smell? Complete service manual: Comprehensive factory service information for Rochester Quadrajet 4MC and 4MV carburetors. $180.00. 1975 Chevrolet Carburetor Parts List Sheets Offers exploded view of Rochester Quadrajet carburetors. Float level may be too low – set to specifications. It needs to move up and down freely. There should be no bubbles. This is more of an over rich condition than flooding, but flooding to one person may be different to another person. Delco . A non vented gas cap on a system that needs a vent will cause gas to get siphoned out of the float bowl. Its purpose is to offset the enriching effects caused byexcessive fuel vapors during hot engine operation.In a perfect world the Idle Compensator should be installed on those applications that need it. The float pin may be worn. Serving our valued customers Since 1980. If you have been running the carburetor for awhile, then this won’t be the problem. When the engine has just been started, there is obviously no vacuum--so no fuel is sucked into the engine to start. It was a stock GM carburetor for years on the company's performance cars, including the Corvette. Includes theory, diagrams, detailed specifications, tune-up data and complete overhaul procedures. Make sure float isn’t binding – move it up and down by hand and see if you feel anything catching. The idle mixture screws are located in the base plate for superior idle quality. Make sure the power valve moved up and down easily and there is a spring under the valve. Flooding fuel will leak out anywhere it can and onto the throttle valves and out the shaft is the 1st place fuel likes to go. Move the float up and down by hand to see if you feel anything catching. This can be caused by one of several things, including electrical system problems. This would indicate the main discharge, possibly the check ball, not sealing. I rebuilt it using a kit I ordered from you. How does the Quadrajet idle work and what can I do when things go wrong. Also watch the needle to make sure it is move straight up and down and not getting caught up. Looking through your parts section I found pt # 17-91 Rochester carb. Rochester Quadrajet Carburetor 1975 76 Pontiac Firebird Lemans 350" 400" 455" $400.00. New pumps are especially suspect. Simply, there is too much gas getting into the float bowl. I don’t have these. Accelerator pump itself may be bad. The cup curled, or is damaged. Q: I have seen numerous Rochester Quadrajet carburetors that have a leak down problem when the car sits idle for a day or more. As the engine heats up, the spring in the manifold expands and puts pressure on the choke to open the choke. Rochester Quadrajet 4 Barrel Carburetor 17080212. It has a spring located in the manifold with a rod running up to the plate. Turn the screw out just until the RPM stops rising and turn the screw one half of a turn further. Manually move the float up and down and watch for any kind of rubbing, or catching. It appeared to be flooding at idle and the fuel was leaking excessively from the throttle body linkages (on both left & right side). There is a pull clip that connects the float needle with the float arm. Do you see gas dribbling out of the main discharge. The gas cap should be vented. Because there are so many different combinations, we cannot possibly duplicate the vacuum signal If your flooding started after a rebuild, then skip this one. QuadraJet Idle Problem from corvetteforum.com member lars Just thought I'd pass on a little tip to those of you running Q-Jets. QUADRAJET 4 MC — 4 MV CARBURETOR (CONT'D.) $41.32 shipping. 75 Rochester 4MC 4MV Carburetor Manual. Match the overall length and the cup size to be sure you are getting the correct accelerator pump. THE CARBURETOR SHOP Troubleshooting. I have this problem with the Q-Jets on my 1972 Electra and 1986 Chevy pickup. Quadrajet 7040205 EH Carburetor. If any fuel can be seen dripping into the engine from the carburetor, the float is stuck or defective and must be repaired. It is a good carburetor for up to close to 400 horsepower. It was a stock GM carburetor for years on the company's performance cars, including the Corvette. Move the throttle by hand just a little and see if the choke snaps closed. When the engine is started, the throttle should be tapped just a little to allow the choke to snap shut. Most carb problems are attributed to dirt. He needs to have all four tubes, 17-91 is one of those numbers. Look for any cracks around the area the seat screws in. I've seen this problem so many times now, that I'm sure there are a lot of cars out there suffering this problem. Free shipping. Rochester Quadrajet Part Numbers for 1965-1974 and Trucks to 1979 This is true for your engine in both performance and mileage. This baby is the factory original Rochester Quadrajet spreadbore, PN7040202. Carburetor Troubleshooting Tips Tech Article Chevy. Also make sure all old gasket residue is gone. ROCHESTER QUADRAJET CARBURETOR 4MV REPLACEMENT “mechanical / divorced choke” also known as “remote choke” 4 Barrel Quadrajet with “SIDE FUEL INLET”. The solution is simple: Remanufacture it. This new carburetor was blended with what Rochester knew about carburetors, mixed with ideas from other manufacturers, (spread-bore design and vacuum secondaries). doesn’t have the secondary accelerating well tubes. A couple of jets can be seen in the front primaries. Bowman has a business degree from Pennsylvania State University and was an officer in the U.S. Army (aircraft maintenance officer, pilot, six Air Medal awards, two tours Vietnam). Replace any fuel filters – There is usually one in the fuel inlet of the carburetor and often there will be an in-line fuel filter. Vacuum leak – Use spray carburetor cleaner and spray around the base of the carburetor and any vacuum lines. Blow out with compressed air. It is a good carburetor for fuel economy and still has stellar performance when required. This means that not only does it not work, it's leaking vacuum and interfering with the mixture in the carburetor. 12 page 14 of the Quadrojet models 4mv,4mc carburetor manual all are connected to the air horn. Make sure float doesn’t rubbing somewhere. 6.5 – 8 grams, depending on which float it is. The choke valve will close once you step on the gas. The engine needs a bit of help when cold. Rochester QuadraJet is a superior carb when tuned and set up right. If the engine runs OK except at an idle, the idle jets may be out of adjustment of dirty. Tune up your automotive and marine Rochester 4 barrel Quadrajet carburetor with our USA made premium carburetor rebuild kits. Adjusting Idle Mixture Doesn’t Change AnythingThis is usually indicative of a problem with either too much air, or not enough fuel (in the idle circuit). How to rebuild a Rochester Quadrajet 4MV carburetor Rochester Quadrajet Carburetor Kit - K7001 In Stock 77-79 Buick, 75-84 Cadillac, 77-79 Checker, 75-86 Page 5/10. Rochester Quadrajet, 4 barrel carburetor idle. I set the float to 3/16 like the instructions stated. When the engine is cold, the spring contracts and creates a pull on the choke to close. Its limit in horsepower applications and ability to be modified was its downfall at the racetrack when horsepower climbed. 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