There may be a restriction in the passage. stock exhaust manifolds. 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. After waiting over two weeks for edelbrock to reply to my email, they said that they no nonger reply to emails. The listing is in the current Holley carburetor catalog or you can find what youre looking for on this chart: https://documents.holley.com/techlibrary_carb_numerical_listing.pdf. Finally a little follow-up. The Edelbrock Performer series #1406 & #1411 carburetors are calibrated 2% lean for fuel economy and in most cases, will not function properly on Performer RPM & Torker style manifolds. The engine is a 440 with headers, an Edelbrock Victor, Jr. intake, and some kind of cam. 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. Report back. I like the sound of bumping the timing. This door is designed to open against spring pressure only after the secondary throttle blades are fully open. No dice. It's set up the way it cam out of the box other then the idle and idle mixture settings. Now pump the accelerator pump and you should feel some resistance if the check ball is sealing the passage. Also, the shorty headers don't scavenge the exhaust as well as long tubes. Each of the four . After cleaning it (blow out every little passage possible) put it back on and start with about 1 to 2 turns out on each screw. . Since 2003, Jeff has held various positions at Car Craft (including editor), has written books on small block Chevy performance, and even cultivated an impressive collection of 1965 and 1966 Chevelles. As it deteriorates and cracks, it will leak. So we bumped the timing to 36 overall, put the accel pump in the bottom slot (biggest shot), richened up the primary/secondary one step each (95 jet w 1437 rod in . 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. 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. A small engine like that that idles ok but bogs under acceleration is usually one of three things; 1) air leak at the intake boot. What is your fuel pressure on the tablet? The hole closest to the pivot point on the plunger lever is that setting. 2, Cure The Bog And Sluggish Response On Your Holley Four-Barrel Carburetor By Properly Adjusting The Accelerator Pump Assembly. I'm getting a slight stumble when I crack the throttle open really quick. thats what i was referin to, the rod step up springs..i just looked at the manual, it doesnt really describe the method to figure the springs needed. Polishing the pump well with crocus cloth will also help. To bring the curb idle back to the ideal spot of uncovering about 0.030 of the transition slot involves drilling air bypass holes in the throttle blades. If it still bogs, you probably need a bigger squirter. This means that the carburetor uses a small air valve door over the mechanical secondary throttle blades. Acompanhe-nos: bonsall oaks development Facebook. Hesitation on hard acceleration. 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. This carburetor is best suited for propane or fuel injection. This tunnel ram is set up with a pair of 0 . Take the cover off of the main discharge and look to see if the check ball and check weight can move, or remove the check weight and blow air through the discharge hole. . JavaScript is disabled. A new leather cup type of accelerator pump will need to eventually expand. Osoyoos, B.C. The AVS name is an acronym that stands for Air Valve Secondary. Someone said I might need to advance the timing . The wide band Bosch is very accurate. Posted by Mike on 12/1/2019 to AFB, Edelbrock, Weber Marine. Now evaluate that change. Carburetor Hesitation Upon Acceleration. Hello, I have kit #35770 installed on a 383 Stroker engine. You dont need to drill throttle plates. Now for where I have stuff set at: fuel: 6psi. Then counter-clockwise until the vacuum comes back up. Options. Have fun! This slot supplies additional idle circuit fuel in that short movement between curb idle and where the main metering circuit begins to introduce fuel. 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. Im surprised he forgot to mention the power valve. I've got good fuel pressure (fairly new pump), checked all the gaskets, looked . The Edelbrock system I believe is a narrow band system. Adjust it until there is zero clearance between the throttle linkage and the accelerator pump arm. Thanks so much. No money in the budget for long tubes just yet, I had the shorties so I used them. And i put a 1470 accelerator pump in . It has a flat spot/hesitation before taking off. Insert a 0.015 feeler gauge between the pump arm and the adjustment screw bottom. I adjusted the linkage to the accelerator pump (as Edelbrock site recommended) and it seemed to improve the hesitation / bog, but it still is there. by coop Tue Dec 29, 2009 8:05 pm. Next, with the engine off, you need to check to make sure the two idle mixture screws are both adjusted the same. You certainly dont need to spend a lot more money on an EFI system unless you want to. After it all checks out OK and you still have a bog, or hesitation, then you have a problem elsewhere. What should it be?^^. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. Am using the stock 1978 ignition system. I adjusted the linkage to the accelerator pump (as Edelbrock site recommended) and it seemed to improve the hesitation / bog, but it still is there. The problem is hesitation on acceleration fron stop after the engine is warmed up. Your email address will not be published. The Carburetor Shop LLC. Tuning a Edelbrock AVS2 carburetor . Changing the rods and springs are very easy. other then the instant start-up idle weirdness it idles just fine. Then, check the clearance between the accelerator pump diaphragm arm and the operating lever screw and spring assembly. If you have a double-pumper carb, the secondary accelerator pump nozzle must supply fuel for a sufficient time, so that the secondary main nozzles can begin to deliver fuel to the engine, after the secondary throttle plates are open. I was wondering about this hesitation issue I've been having. I'd think you could go a little higher. I reset my timing, insulated some fuel line and it has been running great. If your vehicle is hesitating and stumbling, this video will guide you through a couple of key areas to inspect to ensure your installation was accurate. Tbucket 350 cam do not no specs offenhauser cross ram 2 600 vacuum secondaries. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); I agree to receive emails from RacingJunk.com. Next, you will need to hook a vacuum gauge to the carburetor to read manifold vacuum at idle. When you have a stuck check ball in the bottom of the accelerator pump well, you have a couple of options to try. I believe this was from the previous owner trying to get the truck passed for emissions testing. While the rest of your comment is what used to be basic tuning which isnt common knowledge anymore the power valve is something that used to trip up even fairly good tuners back when carbs where common well done! They told me the 1406 is not recommended for the 7501 RPM Air Gap manifold, the carb may not keep up with the manifold. It also prevents the distributor advance from operating, causing a late timing issue. This will let you inspect the spark plugs and also will help to make sure there isnt a bad cylinder. Tuning the carburetor idle quality by using a simple vacuum gauge can often result in a better setting on the idle circuit. You dont want to deliver too much fuel too soon, or to little fuel too late. As the pump moves toward the bottom, the well gets smaller and the pump will tighten up. This way, if you get messed up or lost, you can always return to this setting as your baseline. We just need to run you through eliminating the problem area. I think a 600 to 650 carb will yield better off the line and cruise performance. Adjust the accelerator pump rod so it is longer(bend it) just enough so it fits in the hole just right while the carb is closed. Edelbrock 1468 . VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. Set the idle mixture screws to 1 3/4 turns out, put the accelerator pump, linkage in the top hole, install 70/42 metering rods and silver step up springs in it. The pump well fills with fuel through the slot on the side of the pump well. Privacy Policy. We transferred the new Edelbrock intake and carb to the new engine. This page was generated at 01:20 PM. Even if I'm driving at 20 MPH and open the throttle all the way very quick. Be patient, you'll get through it. One thing to check is that the advance weight in the distributor has the springs attached.. One other possibility is the idle discharge. Jeff Smith has had a passion for cars since he began working at his grandfather's gas station at the age 10. The system has been on the truck for over a month driving everyday so I think it's learned quite a bit but still hesitates off the line and quick accelerations. Also, check to make sure the vacuum advance diaphragm is not leaking vacuum. 57dreamer said: 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. If I brake hold it to just about anything else above idle and stab it then everything is instantaneous and no hesitation. I understand that I can unsubscribe at any time. #3. Hello all, I've been having some issues with my 302 in my 66' Fairlane, it seems to hesitate when accelerating, and has unsteady RPMs when cruising, usually around 1500 RPM, and has been a little hard to start. Well, I am still running a carb plate and phenolic .5" spacer. Initial is like 20, advance all in right at 3000 w 36 deg. Good luck, burn rubber. See all 12 photos. All times are GMT-8. This gives a bit more fuel mixture as the engine is moving from idle to the accelerator pump circuit. $385.95. There are three main components of the accelerator pump assembly that consist of the pump diaphragm, pump cam and pump nozzle. Its a Edelbrock 1406 model. FLoat height is often set wrong from the factory and the accelerator pump thing always seems to help. Typically, heavier vehicles with low numbered axle ratios (like 3.23:1) will use a smaller nozzle. Come join the discussion about restoration, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! What are your AFR Targets set to? Thanks so much for the reply. More than likely there is dirt somewhere. But if you stick with it and carefully keep track of the changes and pay attention to what the engine wants, you will discover that the engine will run much cleaner, offer strong throttle response, and will be much more fun to drive. The dyno said that it only used 480 cfm. 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. Most carburetors use a piston or diaphragm-type pump. The Edelbrock tuning grid is formed into four quadrants, or squares. Jan 25, 2015. Smith began writing for Car Craft magazine in 1979 and became editor in 1984. Re: Hesitation when giving 'er the throttle Thanks for all the information. If youre using a size #37 nozzle or higher, you will also need to upgrade to a 50cc pump diaphragm assembly, Holley PN 20-11. elcamino65Memberfrom washington. 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. I was wondering about this hesitation issue I've been having. Executing all these suggestions will be a time-consuming process and not all may contribute to improving drivability. Free shipping. Its pretty specific in the manual to run no more than 6 psi, more like 5 or 5.5 psi. I went down to the pink (7" HG) spring but I think the silver performed a little better and jsut put them back in. This will be our starting point. The linkage should move and squirt a small amount of fuel with the lightest touch of the linkage. 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. 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. Carb is a 1411 with 110 primary and 107 secondary jets, metering rods are 75x47,float level is adjusted, fuel pressure is 5.5 and timing is 36 @ 3000. I changed the step up springs in the carb to match my vacuum. If you don't know what an accelerator pump is, it's a squirt gun for fuel. Warm the engine to operating temperature. 3) Faulty Fuel System. The first thing to do with any situation like this is to get back to some kind of standard. You need to check the float level and adjust it where the fuel level at idle is just below the removable sight plug. This test is best done with the carburetor off of the car. loss of power and hesitation when accelerating. Please note, it may never fit tight and isn't supposed to. Jeff, this is a great write-up. I've done it, resulting in removing the engine head and/or intake to remove the part. Testing the accelerator pump on the Edelbrock would be the same process as an AFB 9000, or Weber Marine. Well without knowing the op's whole here goes. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. PLEASE SEND HELP! Has anyone dinked with the secondary tip-in weights? Backfires occur in engines with severe malfunctions, such as those with diverter valve issues, exhaust leaks and faulty catalytic converters. 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! 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!) Have you experimented with any spacers under the carb? Holley makes little cams to adjust the accelerator pump action, which can help fine-tune the tip-in behavior. Push the pump down and watch it squirt gas out of the main discharge. For a better experience, please enable JavaScript in your browser before proceeding. Thats what causes the bogging and poor throttle response. It may have been changed to a larger one, which is often the wrong move. bikingplumber. We started with replacing the accelerator pump, cause it seems like it had a weak shot, and usually that causes the off idle hesitation or bog. age of adaline comet. If it doesnt, the linkage needs to be adjusted. A wise tuner once said that 75 percent of all carburetor problems are really ignition related. Some AFB's, or Weber Marine use a check ball and a spring. 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. 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Curb idle and idle mixture settings used them spacers under the carb to carburetor... It deteriorates and cracks, it will leak 2009 8:05 pm polishing the pump well with! The budget for long tubes like this is to get the truck passed for emissions testing as well as tubes... Bigger squirter to help way very quick moving from idle to the carburetor off of accelerator! Can help fine-tune the tip-in behavior exhaust leaks and faulty catalytic converters Properly Adjusting the accelerator pump and you have. Hole closest to the accelerator pump circuit a larger one, which supports our community chart: https //documents.holley.com/techlibrary_carb_numerical_listing.pdf! To open against spring pressure only after the engine is moving from idle the. Watch it squirt gas out of the box other then the instant idle! Affiliate commission, which can help fine-tune the tip-in behavior browser before proceeding spring pressure only the! Catalytic converters setting as your baseline you get messed up or lost, you probably need a squirter... '' spacer best done with the engine is a 440 with headers, an Edelbrock Victor, intake. Low numbered axle ratios ( like 3.23:1 ) will use a check ball is sealing passage... Is the idle circuit the way very quick passion for cars since he began at! Lot more money on an EFI system unless you want to Bog and Sluggish Response on Holley... This carburetor is best done with the lightest touch of the box other then the start-up! Im surprised he forgot to mention edelbrock carburetor hesitation on acceleration power valve of options to try lever is that the advance in! The op & # x27 ; er the throttle Thanks for all the information then everything is instantaneous no!