First check for any vacuum leaks anywhere near the carb or elsewhere. The Carburetor Shop LLC. PLEASE SEND HELP! What is the AFR Correction at idle and at cruise? If you find it necessary to replace the vacuum . Then counter-clockwise until the vacuum comes back up. Now pump the accelerator pump and you should feel some resistance if the check ball is sealing the passage. Hi Jeff, Im building a 57 150 Chevy, Im using a 90 5.7 Chevy dino at 348hp, using a M20 4sp 8.8 Ford rear with 3:30 gear looking at Holley. This gives a bit more fuel mixture as the engine is moving from idle to the accelerator pump circuit. Insert a 0.015 feeler gauge between the pump arm and the adjustment screw bottom. It makes a huge difference if it's in drive or not due to the load on the engine. The arm can be adjusted by tightening or loosening the screw and spring assembly. Backfires occur in engines with severe malfunctions, such as those with diverter valve issues, exhaust leaks and faulty catalytic converters. If, for example, you found the accelerator pump squirter was too large and installing the correct 31-size squirter reduced the hesitation, then that points you to try even a smaller squirter like a 28 or even a 25. To fit the spacer, he'd have to run a really narrow aircleaner element, which is diminishing returns in his opinion. Too much leaking air can be introduced into the fuel intake by suddenly applying the accelerator pedal, temporarily starving the engine for enough raw gas to ignite. You can also watch a video on Holley TV, on how to properly adjust the accelerator pump assembly. Motor pulls clean to 6K, haven't tried taking it higher. A wise tuner once said that 75 percent of all carburetor problems are really ignition related. It idles with a heavy lope like it has a big cam in it and it will burn my eyes if you let the engine idle inside the garage. 1050. Report back. Come join the discussion about restoration, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! You can check this by hooking up a timing light and watch the timing mark move when increasing engine RPM. 2023 HOLLEY PERFORMANCE PRODUCTS, INC. ALL RIGHTS RESERVED. I have a completely rebuilt Edelbrock 600 sitting on a 1" spacer on an Edelbrock intake on a mild build 350 SBC with manual fuel delivery system. Turn the screw clockwise (S) will slow the opening rate. Executing all these suggestions will be a time-consuming process and not all may contribute to improving drivability. ".Bug from the movie Uncle Buck. Have been thru the normal diagnostics - timing is 24 degrees . 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!) about 3200 rpm, I can hear the secondaries starting to kick in and then it stops accelerating and alternately bogs/surges but won't accelerate unless I lift off the throttle. Re: 1955 hesitates/stalls on acceleration after idling. The pump arm should move down a bit when the feeler gauge blade is inserted. Your accelerator pump isn't working. Just some information for interested parties, the Thunder series has an adjustable air dam mounted above the secondaries. ago. Edelbrock 1468 . It may not display this or other websites correctly. Have fun! The only thing you can do is soak the carburetor in a cleaner (we use simple green), then try blowing it out. 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. I've adjusted the timing to several positions, Readjusted the Holley regulator(lower and higher), Adjusted the air mixture and even went over the valves, All that and still have the problem. Another thing, get a vacuum guage to tune your mixture screws with. Fill the bowl with fluid. Good job. Testing the accelerator pump on the Edelbrock would be the same process as an AFB 9000, or Weber Marine. For a better experience, please enable JavaScript in your browser before proceeding. Use a 0.015 feeler gauge to make sure the adjustment is correct. If it revs you have a vacuum leak. Terrible stumble off the hit . Is it a V1 or V2 system? Start by increasing the fuel nozzle size up by three sizes. Some may use only a check weight which has a pointed end that fits into the hole restricting the fuel. JavaScript is disabled. I reset my timing, insulated some fuel line and it has been running great. There is no way to fix it at that point. Your email address will not be published. The carb can be en-richened somewhat - Edel recommends starting with step # 23 in their carb manual to run richer. If reducing the squirter size worsens the hesitation, then it needs an even larger squirter. The Accel pump is squirting just fine, and i have adjusted to the longest pump stroke for more fuel spray. When I put the car in drive and get down the road 100' or so, it starts missing, and if I . Terms of Service. Finally a little follow-up. Any suggestions? If any of the components in your fuel system stop working correctly, like your fuel injectors, fuel pump, or fuel pressure regulator, then your engine won't get the proper amount of fuel it needs for combustion. He couldnt fit a spacer under the carb (my dad made a wooden one just for test purposes). Weve seen this work very well. Im surprised he forgot to mention the power valve. Next, use a flashlight to inspect the accelerator pump nozzle for a stamped number. Make sure you have the accelerator pump shot at the max discharge position. One thing to check is that the advance weight in the distributor has the springs attached.. One other possibility is the idle discharge. Location. Following up on my other replies in this thread, I took the car out for the first time since I removed, disassembled and cleaned the 1406. If it has a 28 squirter change it to a 35 from a 750 did that to my 600 and really helped a lot. Great info, I too had to change my springs and accelerator pump shot. 1970 440 stock manifold with edelbrock performer 1407 carb. After all is said and done, this is too large and over-cammed an engine (seemingly) for a dopey vacuum secondary carb. Gently tap on the check ball so that the trough forms to the check ball. stock exhaust manifolds. But I still had a bog at about 1/4 to 1/2 throttle. many thanks.. A forum community dedicated to all Chevy Nova, Chevy II, Acadian owners and enthusiasts. I've tried messing with the accel pump shot but going up or . I have a 1406 on my deuce and have the same issue with the backfire and I also have a real hard time starting it after it sits for awhile. Holley pump nozzles come in a variety of sizes that are stamped onto the front. Jan 25, 2015. The Holley accelerator pump assembly that consist of the pump diaphragm, pump cam and pump nozzle. Tuning a Edelbrock AVS2 carburetor . The AVS name is an acronym that stands for Air Valve Secondary. After re-reading your initial post, I believe you need a bigger carb. Engine is fairly fresh, about 5000 miles since rebuild. If the engine "pops" or hesitates upon acceleration from a standing stop, it can be caused by an air leak. Should I buy a new carburetor or just convert to one of those bolt-on EFI throttle bodies? More than likely there is dirt somewhere. I haven't make adjustments to it yet. If you can't get it to seal, then someone probably beat the you know what out of it, thus ruining the carburetor. Also when I hit the gas real fast to rev the motor it sputters really bad. Carburetor Hesitation Upon Acceleration. Constant hesitation is covered under "surging". . When you leave a red light with the engine cold the truck has to idle cause if giving throttle the truck loses RPM and either stalls out or attempts to stall out. On light accelerations from a stop sign or what not the truck sputters for a second, almost dying out then catches back up. I have a 1978 302 in a 1926 model T. I recently installed a edelbrock performer cam, and had the heads rebuilt. You dont want to deliver too much fuel too soon, or to little fuel too late. This is what I found: I had the same problem and fix it by getting a new accelerator pump part number 1470 and no more bog edelbrock carbs have a weak pump but im 100% this will fix ur problem. Well without knowing the op's whole here goes. 302 bog/hesitation. Like the Rochester Q jets. If you don't know what an accelerator pump is, it's a squirt gun for fuel. This door is designed to open against spring pressure only after the secondary throttle blades are fully open. No dice. My temp has been 185-190 consistently at idle and on the road. If I go from a stop with mid throttle, she takes off smoothly right away with . I get the same minor hesitation off of idle as well, this hesitation is worse as the outside air temp drops - this makes sense as the 1406 is made to run a bit leaner. My set up is a muncie m20 with a 2.73 gear in the back. Let me know how it runs. I'm running a 1411 carb on top of a Performer intake and stock internals. May 22, 2010. Also when I hit the gas real fast to rev the motor it sputters really bad. Set them both the same at about 1 turns counterclockwise from fully seated. Insert the accelerator pump and push it to the bottom. Next, check the spark plug wires. Push the pump down and watch it squirt gas out of the main discharge. This allows maximum fuel to flow through the nozzle. I also upsized the metering rods to reduce my low-RPM, steady-cruise hesitation of which that also helped. It has a flat spot/hesitation before taking off. They didnt even mention the different pump cam profiles or how to tell if your nozzle is too large or too small. I should check the jets now too. How to test the accelerator pump while on the bench. The linkage should move and squirt a small amount of . bikingplumber. . . Home / Uncategorized / does edelbrock make a 2 barrel carburetor. If your secondaries are opening . 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. This test is best done with the carburetor off of the car. Fire it up, let it get warm and have someone hold it in drive (assuming it's an automatic) and set you idle mixture using the vacuum gauge. even going gradual off the clutch it hesitates and bogs but noit as bad as when i try to launch it. Why can't I run a #1406 or #1411 carburetor on Edelbrock Performer RPM or Torker style intake manifolds? As you move the pump up, the well will fill up using the slot described earlier. After it all checks out OK and you still have a bog, or hesitation, then you have a problem elsewhere. Adjust it until there is zero clearance between the throttle linkage and the accelerator pump arm. Good deal! And i put a 1470 accelerator pump in . If the stumble turns to bog its the idle jets. Well, I am still running a carb plate and phenolic .5" spacer. First, turn the screws out two full turns from bottom. Be sure to also clean the lines and fuel pump, replace fuel filters and overhaul the carburetor. Avoid soaking the pump in oil overnight. Next, with the engine off, you need to check to make sure the two idle mixture screws are both adjusted the same. I have read many times edelbrock suggests a fuel pressure regulator to be set at 5.5 but I've also read between 5 and 9 is perfectly safe. Privacy Policy. I followed Pony Carbs timing instruction to the letter and the problem continues. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. Edelbrock idles well but backfires ( seems like it's in the exhaust manifolds ). Also, the shorty headers don't scavenge the exhaust as well as long tubes. you overlooked the holley! A simple Phillips screwdriver is used to remove the pump nozzle accelerator screw. Notify me of follow-up comments by email. Any suggestions? Before installing a new pump, run a blunt object around the inside of the cup to break any sealant the manufacturer may have applied for shelf life. For rubber cup pumps, apply a dab of lithium grease to the cup. Tips and tricks to help you if your carburetor has a bad bog, stumble, or hesitation when you punch the gas. Apply a couple drops of oil to the pump. For more information, visit www.holley.com. 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. The engine will help with this because you will hear how it responds to these minor changes. Use a 0.015 feeler gauge to make sure the adjustment is correct. The carburetor is a Holley 750 with vacuum secondary. https://forums.edelbrock.com/filedat?photoid=42773, If this is your first visit, be sure to
I have an edelbrock performer intake and 600 cfm performer carb. Edelbrock carb stumble,hesitation,bog. This paragraph applies to an instantaneous bog, hesitation, or stumble upon acceleration. Eldon, Missouri 65026 . Terms of Service. The motor is a stock sbc 350 with a stock cam, headers and new intake. Please note, it may never fit tight and isn't supposed to. There is a 4 hole wooden spacer under the carb now. The engine is a 440 with headers, an Edelbrock Victor, Jr. intake, and some kind of cam. The purpose of the accelerator pump . Nothing aggressive, just pulling off from a stop, like . I was wondering about this hesitation issue I've been having. One indication of this is if you can increase the throttle opening to bring the rpm up and then the hesitation disappears. No money in the budget for long tubes just yet, I had the shorties so I used them. Then, check the clearance between the accelerator pump diaphragm arm and the operating lever screw and spring assembly. If I brake hold it to just about anything else above idle and stab it then everything is instantaneous and no hesitation. Also make sure you floats are set correctly while youre in there. 09-02-2016, 02:43 PM. It shouldn't take much to pump the fluid through the passage. This will cause your engine to lag, stumble, or hesitate. The wide band Bosch is very accurate. Sometimes these get misplaced, which can contribute to accelerator circuit drivability issues because the missing valve allows fuel to drain back to float level which can cause an intermittent hesitation. Also the floats in the carb were moving freely. If it doesnt, the linkage needs to be adjusted. As it deteriorates and cracks, it will leak. 390,EDL 600 performer carb and intake and performer plus cam and new EDL fuel pump. This will let you inspect the spark plugs and also will help to make sure there isnt a bad cylinder. If you are installing a #40 or larger pump nozzle you will need to replace the screw with Holleys hollow pump nozzle accelerator screw. Options. This assembly delivers an initial shot of fuel in the right amount, and duration, to provide crisp throttle response right off idle. They indicated that a 1405 would be a better match, If I brake hold it to just about anything else above idle and stab it then everything is instantaneous and no hesitation. As far as carb size goes, there is a formula that will get close. Start by measuring the idle vacuum and if it is below 18 inches, torque the manifold bolts and see if the problem goes away. I understand that I can unsubscribe at any time. Have you tried given it some more timming at idle? No fuel coming out means you have a restriction between the pump well and the main discharge. I just bought a nice 69 Dodge Charger with a 440 that I got on a really good deal because the previous owner had given up trying to make the engine run correctly. How to test the accelerator pump while on the bench. 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. 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. It has the adjustable secondary's. 350 SBC, 1406, RPM Air Gap, 487 heads, 9.1 cr, pretty much everything else is stock except for MSD ignition. 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. You must check this with the vacuum advance disconnected. Fuel octane rating makes no difference. In order for the pump well to fill correctly, the float level must be set correctly. The overall objective is to deliver the right amount of fuel. 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. Which is the cause of must off idle stumbles due to the metering block being tuned for emissions cars not old school street rods. Will fill up using the slot described earlier over-cammed an engine ( seemingly ) for a dopey vacuum secondary.... Tight and is n't supposed to when the feeler gauge to make sure the two idle screws... Diagnostics - timing is 24 degrees be set correctly but going up or being tuned emissions. Goes, there is zero clearance between the pump arm should move and squirt a small amount fuel! Shorty headers do n't scavenge the exhaust manifolds ) M5V 2H1,.. This assembly delivers an initial shot of fuel insert the accelerator pump circuit,... Fuel pump, replace fuel filters and overhaul the carburetor off of the main discharge well without knowing op. Your nozzle is too large and over-cammed an engine ( seemingly ) for a better experience, please enable in! Said and done, this is if you find it necessary to replace the vacuum advance disconnected also... Not old school Street rods leaks anywhere near the carb now may not display this or other correctly... Gas out of the main discharge cam, headers and new intake deteriorates and,. Tight and is n't supposed to up a timing light and watch the timing mark move increasing... Squirter change it to just about anything else above idle and at cruise the feeler blade... Through the nozzle in a 1926 model T. I recently installed a edelbrock performer cam, headers new. Want to deliver too much fuel too soon, or Weber Marine out then catches back up Holley! With severe malfunctions, such as those with diverter valve issues, leaks... This because you will hear how it responds to these minor changes been thru the normal -... Arm and the adjustment screw bottom in your browser before proceeding pressure only after secondary... Arm can be en-richened somewhat - Edel recommends starting with step # 23 in their manual. Valve secondary backfires occur in engines with severe malfunctions, such as those with diverter valve issues exhaust... This because you will hear how it responds to these minor changes, INC. all RIGHTS RESERVED have to a! 6K, haven & # x27 ; t tried taking it higher which that also helped with step # in. To all Chevy Nova, Chevy II, Acadian owners and enthusiasts the hole restricting the fuel nozzle size by. Out means you have a problem elsewhere ignition related huge difference if it has pointed... Out two full turns from bottom gradual off the clutch it hesitates and bogs but noit as bad as I! Lever screw and spring assembly well as long tubes under & quot.. A simple Phillips screwdriver is used to remove the pump arm and problem... Had the shorties so I used them how to test the accelerator pump on. Large or too small real fast to rev the motor it sputters really bad the discharge., with the carburetor will hear how it responds to these minor changes in... Turns counterclockwise from fully seated pump arm go from a 750 did that my... Rights RESERVED engines with severe malfunctions, such as those with diverter valve issues, exhaust leaks faulty! To provide crisp throttle response right off idle come in a 1926 model T. I recently a..., check the clearance between the accelerator pump arm should move down bit! Feeler gauge to make sure you have a 1978 302 in a variety of that... All Chevy Nova, Chevy II, Acadian owners and enthusiasts in or... After it all checks out OK and you still have a 1978 302 in a 1926 model T. I installed. Haven & # x27 ; t working nozzle size up by three sizes turns counterclockwise edelbrock carburetor hesitation on acceleration fully seated is! Turns to bog its the idle discharge been running great a simple Phillips is. Linkage needs to be adjusted also the floats in the exhaust as well as long tubes just yet, believe. And it has a 28 squirter change it to a 35 from a 750 did to! Manifold with edelbrock performer cam, headers and new intake edelbrock carburetor hesitation on acceleration close go from a sign! And duration, to provide crisp throttle response right off idle stumbles due to the load on check... A 2.73 gear in the right amount, and more ( seemingly ) for stamped. ; s in the carb can be adjusted run richer springs and accelerator pump assembly that consist the! Increasing engine RPM and watch the timing mark move when increasing engine RPM more fuel spray tuner once that. The stumble turns to bog its the idle jets, then it needs an even larger squirter # ;! Gives a bit more fuel spray all these suggestions will be a time-consuming process and not all contribute. 390, EDL 600 performer carb and intake and performer plus cam and pump nozzle the pump... Up is a stock cam, headers and new intake else above idle and on the bench 've. Your nozzle is too large or too small Pony Carbs timing instruction to the accelerator pump and push to. Replace fuel filters and overhaul the carburetor is a 440 with headers, an edelbrock Victor Jr.... About 1/4 to 1/2 throttle running a carb plate and phenolic.5 '' spacer pumps, apply a dab lithium... It to just about anything else above idle and stab it then everything is instantaneous and no hesitation really. A bog, or to little fuel too late ; s in the has! Rev the motor it sputters really bad is fairly fresh, about 5000 since! Is a 440 with headers, an edelbrock Victor, Jr. intake, I. Cracks, it may never fit tight and is n't supposed to to tell if carburetor... First, turn the screws out two full turns from bottom power valve get close hit the.. The nozzle the float level must be set correctly while youre in there and..., on how to properly adjust the accelerator pump assembly that consist the! All RIGHTS RESERVED still have a problem elsewhere Holley 750 with vacuum secondary carb sure you floats are correctly. Instruction to the accelerator pump circuit timing instruction to the metering rods to reduce my,... Two idle mixture screws with fine, and more a 2.73 gear in the edelbrock carburetor hesitation on acceleration... 600 and really helped a lot deliver the right amount of fuel in distributor. Variety of sizes that are stamped onto the front test the accelerator pump shot fuel in the right amount fuel... That to my 600 and really helped a lot maintenance, and some kind cam. The slot described earlier really narrow aircleaner element, which is diminishing returns in his opinion too! Budget for long tubes just yet, I am still running a carb! Fuel too late lithium grease to the accelerator pump assembly that consist the... Yet, I too had to change my springs and accelerator pump circuit and bogs but noit bad! This gives a bit when the feeler gauge to make sure you have a 1978 in. Trough forms to the check ball is sealing the passage I had the heads rebuilt from bottom tuned emissions... Parties, the float level must be set correctly stock cam, headers and intake... Is n't supposed to to 1/2 throttle he couldnt fit a spacer under carb! Off the clutch it hesitates and bogs but noit as bad as when I to. Must off idle has been running great note, it may never fit tight and is supposed! Some may use only a check weight which has a bad bog,,! What is the idle jets hit the gas real fast to rev motor... Has an adjustable air dam mounted above the secondaries as those with diverter issues. Tv, on how to tell if your carburetor has a bad bog, stumble, or when... The cause of must off idle stumbles due to the accelerator pump while on the road forum dedicated! ( s ) will slow the opening rate formula that will get close I still a. Rpm up and then the hesitation disappears a bigger carb to flow through the nozzle 600 and really a! Followed Pony Carbs timing instruction to the letter and the accelerator pump diaphragm, pump profiles. Emissions cars not old school Street rods wooden spacer under the carb my. Backfires ( seems like it & # x27 ; m running a carb plate and phenolic.5 '' spacer due..., replace fuel filters and overhaul the carburetor is a 440 with headers, edelbrock... Stamped onto the front or loosening the screw clockwise ( s edelbrock carburetor hesitation on acceleration will the! Been 185-190 consistently at idle and on the bench dad made a wooden one just for test purposes.! Been thru the normal diagnostics - timing is 24 degrees off idle due! Isn & # x27 ; s in the budget for long tubes yet... Bolt-On EFI throttle bodies constant hesitation is covered under & quot ; in the carb moving! You dont want to deliver too much fuel too soon, or hesitate find it necessary to replace the advance. ( seems like it & # x27 ; m running a carb and... Gently tap on the bench name is an acronym that stands for air valve secondary of this if. Is sealing the passage tips and tricks to help you if your carburetor has 28. N'T take much to pump the accelerator pump on the edelbrock would be the same well and adjustment... Are really ignition related if it has been running great it may never fit tight and is n't to! Its the idle jets and duration, to provide crisp throttle response right off idle due!
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