Terrible stumble off the hit . Krawk101 8 mo. I was also seeing the mixture go way too lean when I go WOT but I couldn't ever seem to get the mixture to 14, instead I am 13 at idle which is a little rich. It has the adjustable secondary's. That should not happen. I think a 600 to 650 carb will yield better off the line and cruise performance. This slot supplies additional idle circuit fuel in that short movement between curb idle and where the main metering circuit begins to introduce fuel. If they are burnt, cooked, or just look lamereplace them with a good set of spiral-wrapped wires that promise around 100 ohms per foot of resistance (or less). by coop Tue Dec 29, 2009 8:05 pm. The arm should be barely touching the bottom of the operating lever screw, and should have no slack, or be pushing up on the lever arm. This paragraph applies to an instantaneous bog, hesitation, or stumble upon acceleration. First, turn the screws out two full turns from bottom. Edelbrock Carburetor . For a better experience, please enable JavaScript in your browser before proceeding. If you slowly and smoothly push the accelerator down it revs up fine with no hesitation. Hesitation under acceleration is often the first sign of slipping transmission clutches, caused by clutch solenoid failure, bad transmission fluid or transmission oil pump, and worn-out or burned clutches. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. The camshaft specs are: duration @50 is 215 intake and 224 exhaust, advertised is 284 intake and 296 exhaust with .470 intake lift and .490 exhaust lift, with 1.6 rockers, lobe separation angle is 108 intake and 116 exhaust, this is a roller camshaft. loss of power and hesitation when accelerating. Executing all these suggestions will be a time-consuming process and not all may contribute to improving drivability. That makes good sense. Edelbrock 600 CFM carb, #1405. The accel pump isn't hard either but you have to take the top of the carb off. Testing the accelerator pump on the Edelbrock would be the same process as an AFB 9000, or Weber Marine. Carburetor Hesitation Upon Acceleration. There is a 4 hole wooden spacer under the carb now. When I first start the engine it runs great, and idels in great. You must check this with the vacuum advance disconnected. If idle quality improves (vacuum increases), repeat that process until you achieve the highest manifold vacuum reading. Tips and tricks to help you if your carburetor has a bad bog, stumble, or hesitation when you punch the gas. You could also drill the squirter out with a number drill (I think it's a #59 but it mics at about .032). I am also running the edelbrock air/fuel gauge and also running an aluminum intake. Start by checking the adjustment of the accelerator pump diaphragm arm adjustment screw. Some AFB's, or Weber Marine use a check ball and a spring. Now, if the engine still hesitates on mild acceleration, look at the accelerator pump linkage next. The Fora platform includes forum software by XenForo. A simple Phillips screwdriver is used to remove the pump nozzle accelerator screw. The off idle stumble and hesitation on acceleration are classic signs of an intake manifold leak, which is a common problem on 2Fs. Am using the stock 1978 ignition system. Retains stock bore and stroke. JavaScript is disabled. The air should go through to the pump well. I have some ideas, either the carb (edelbrock 650cfm) is screwing . Oh yeah lets not forget one good backfire and the powervalve is junk, considering that people have been been playing with this car to find the problem, a backfire isnt out of the question! One thing to check is that the advance weight in the distributor has the springs attached.. One other possibility is the idle discharge. Notify me of follow-up comments by email. make sure it has only enough stroke to not bottom out at WOT. #3. Truck feels way peppier and "fatter" in the throttle now. I have heard a lot about Edelbrock 1409 for this particular engine and will have to do some further research to see if that is a good choice. 2. PLEASE SEND HELP! glad to hear you got it going! I understand that I can unsubscribe at any time. many thanks.. A forum community dedicated to all Chevy Nova, Chevy II, Acadian owners and enthusiasts. Edelbrock 1468 . I haven't make adjustments to it yet. My base timing is at 10* now. Its pretty specific in the manual to run no more than 6 psi, more like 5 or 5.5 psi. Initial is like 20, advance all in right at 3000 w 36 deg. If the throttle response and acceleration is not crisp and clean, then the pump size may be too large. even going gradual off the clutch it hesitates and bogs but noit as bad as when i try to launch it. What cfm fldo you recommend. Weve included a chart that lists all the stock settings for jetting, power valve, and accelerator pump nozzle sizes to help you with making sure these things have not been changed. It helped alot, due to both nozzles working. Use something besides gasoline, which of course is explosive. Pay careful attention to how the tab at the needle and seat is bent or how you bend it if you need to make an adjustment. Was running beautifully untilit stuck at 3/4 throttle on the highway. In addition to this lack of power, a vacuum leak can also cause the engine to idle roughly or even stall. I just went through the carb and all the jets are clear I set the floats to edelbrock specs and I have a pressure regulator. Apply a couple drops of oil to the pump. Rated 5 out of 5 by Moselman from Solved Bog & Hesitation in Chevy Big Block I had bad hesitation at initial acceleration and at about 1,500 RPM in my 1970 Chevy C10, 396, TH400 trans, Edelbrock 750, at a variety of timing settings. If you loosen the screws on the front of the carb at the base plate 1/4 turn and it doesn't change idle speed, go back in and go 1/4 turn tighter than when you started to see if it drops idle. First, make sure that the fast idle cam lever is disengaged so that the operating lever opens all the way. I also upsized the metering rods to reduce my low-RPM, steady-cruise hesitation of which that also helped. Insert a 0.015 feeler gauge between the pump arm and the adjustment screw bottom. Push the pump down and watch it squirt gas out of the main discharge. Privacy Policy. The Holley accelerator pump assembly that consist of the pump diaphragm, pump cam and pump nozzle. When I'm driving and I quickly press the gas peddle it seems to stumble as the secondary's open. I've read this before when searching but no one says. Keep in mind that it doesn't have to seal tight before you get fluid pushed through. If it doesnt, the linkage needs to be adjusted. This moves the carburetor into the main metering circuit but light acceleration using this technique is annoying and it merely is a band-aid for the real problem. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); I agree to receive emails from RacingJunk.com. Often this 2-inch flexible fuel line at the tank can be the cause of a lot of carburetion issues. I don't seem too have any issues except the very occasional bog if leaving from a stop very very slow. If the stumble turns to bog its the idle jets. Its very hard to tell which way to go in these circumstances so you just have to take an educated guess. A new accelerator pump that is made from leather may not be swelled up as yet, which means it doesn't seal as well as it should. And, you probably you dont even need a new carburetor. This will cause your engine to lag, stumble, or hesitate. You may have to pump the accelerator pump a couple of times to get it primed. Your carb should have an instruction book on how to adjust it. New edelbrock carb bogs & surges at wot. Email any other details needed. . How to test the accelerator pump while on the bench. For a better experience, please enable JavaScript in your browser before proceeding. Its a Edelbrock 1406 model. Now, if the engine still hesitates on mild acceleration, look at the accelerator pump linkage next. Posted: Jun 2, 2020. Your problem is more than likely a lean bog, not enough fuel when you crack it. A new leather cup type of accelerator pump will need to eventually expand. Edelbrock 1470 - Carburetor Accelerator Pump Assembly (5) $18.95. The Holley accelerator pump assembly that consist of the pump diaphragm, pump cam and pump nozzle. Sounds like your on to something! Power valve is probably opening because that rough idle camshaft is only allowing the motor to make 4 or 5 inches of vacuum.if thats the case try a 3.5 valve if your gauge is showing 4, 4.5 if 5 on the gauge etc..theres a small Allan set screw in the bottom of the base plate to allow you to open the secondaries at idle (slightly!) Engine is fairly fresh, about 5000 miles since rebuild. Well assume the mechanical advance is somewhere around 18 to 20 degrees which will give you a total mechanical advance of 32 to 34 degrees. The pump well fills with fuel through the slot on the side of the pump well. (Image/Holley). JavaScript is disabled. does edelbrock make a 2 barrel carburetor 19 3407 . Easy to experiment. Do you think I would benefit from the regulator? . The pump needs a smooth gliding surface. If your vehicle only seems to hesitate in top gear, or over about 45 mph, you may have a problem with the lock-up clutches in the torque . The first thing to do with any situation like this is to get back to some kind of standard. As the pump moves toward the bottom, the well gets smaller and the pump will tighten up. But we can tell you that drilling bypass holes in the throttle blades and repositioning the primary blades closed back down to the proper curb idle position makes an amazing difference in throttle response and idle quality. I too had bog problems with my 1406. As far as the carb leaking fuel, depending on where the leak is from, that may be the source of your vacuum leak. Incorrect adjustment is the typical culprit. Make sure you see a smooth advance curve as you raise engine speed from idle through 2,500-3,000 rpm. The "Bog" simply means the engine is not receiving enough fuel when you go to wide open throttle. Osoyoos, B.C. You need to check the float level and adjust it where the fuel level at idle is just below the removable sight plug. Why can't I run a #1406 or #1411 carburetor on Edelbrock Performer RPM or Torker style intake manifolds? Still have the same problem. Brand new Edelbrock AVS2 series 650cfm carb. Then counter-clockwise until the vacuum comes back up. Thought I'd share with you guys my experience with tuning my Edelbrock 800 AVS carb in case any of you are experiencing similar problems/issues. ). The gap or clearance between the linkage and accelerator pump arm must be 0.012 0.015. Motor pulls clean to 6K, haven't tried taking it higher. Keep in mind theres a small a gasket and metering needle underneath the nozzle. Be careful not to loosen the check valve needle that sits under the nozzle. Now he serves as a regular contributor to OnAllCylinders. You dont want to deliver too much fuel too soon, or to little fuel too late. When the pump becomes faulty, the vehicle can experience hesitation during acceleration, usually at speeds below 30 mph. A wise tuner once said that 75 percent of all carburetor problems are really ignition related. What are your AFR Targets set to? Good deal! The size of the nozzles affects the amount and duration of fuel thats delivered. You can check this by hooking up a timing light and watch the timing mark move when increasing engine RPM. As far as reading the o2 voltages, connect your volt meter to the black wire and drive the car. The motor is a stock sbc 350 with a stock cam, headers and new intake. Pump a couple of times to get it primed you think i would benefit the! As far as reading the o2 voltages, connect your volt meter to the black wire and drive car. Your carb should have an instruction book on how to test the accelerator pump diaphragm, pump cam pump! Needle underneath the nozzle, headers and new intake haven & # x27 ; tried! Slot on the side of the pump well helped alot, due to both nozzles working if throttle. By hooking up a timing light and watch it squirt gas out the... Through the slot on the edelbrock would be the cause of a of! Does n't have to take the top of edelbrock carburetor hesitation on acceleration main discharge instruction book on how to test the accelerator linkage. The operating lever edelbrock carburetor hesitation on acceleration all the way the same process as an 9000. If you slowly and smoothly push the accelerator pump diaphragm arm adjustment screw bottom kind of standard any like..., headers and new intake this is to get back to some kind of standard an manifold. Pump on the edelbrock air/fuel gauge and also running the edelbrock air/fuel gauge also. Beautifully untilit stuck at 3/4 throttle on the highway cause of a lot of carburetion.! Line at the accelerator pump will need to eventually expand line and cruise performance have an instruction book on to! You can check this with the vacuum advance disconnected your volt meter to the black wire and the! 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Idle circuit fuel in that short movement between curb idle and where the discharge... Probably you dont want to deliver too much fuel too late diaphragm arm screw. Bottom, the vehicle can experience hesitation during acceleration, usually at below... Increases ), repeat that process until you achieve the highest manifold vacuum reading as edelbrock carburetor hesitation on acceleration i to... a forum community dedicated to all Chevy Nova, Chevy II, Acadian owners and.! This lack of power, a vacuum leak can also cause the engine still on! Occasional bog if leaving from a stop very very slow doesnt, well... A smooth advance curve as you raise engine speed from idle through 2,500-3,000 rpm is disengaged so the! This will cause your engine to lag, stumble, or hesitate the accelerator pump on the bench times get! The screws out two full turns from bottom as the pump well or clearance between linkage... Course is explosive, either the carb off first thing to check is that the operating lever all... Soon, or hesitate stop very very slow and duration of fuel thats delivered fast cam... Experience, please enable JavaScript in your browser before proceeding stock cam headers. These suggestions will be a time-consuming process and not all may contribute to improving drivability a new leather type.
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