Hi guys, I finaly fixed all (hopefully!) Join. Check your float level. Check the float level to make sure it is correct. If it has enough overlap for a loping idle, fuel injection wont have enough vacuum to not be a pain in the butt to tune. most likely the idle jet is to lean. Assuming the electrical system is working correctly then you either have a vacuum leak, or not getting enough fuel. Post rebuild, and with no noticeable change in symptoms, I pulled a plug (all new) and found them to be black with soot buildup. For a better experience, please enable JavaScript in your browser before proceeding. This should travel up to the top of the carburetor. They didnt even mention the different pump cam profiles or how to tell if your nozzle is too large or too small. If I lift on the pedal or if I go harder on the pedal it will recover. I had a similar problem with my 383 with Holley carb. With engine off, look down the carburetor. Spray carburetor cleaner into the throat of the carburetor. 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. If the intake manifold/head surfaces are not perfectly square and parallel or if the intake gaskets are not properly fitted to cover the ports on the interior side of the manifold/head interface, this can happen. The engine will help with this because you will hear how it responds to these minor changes. This video will guide you in making minor tweaks to get your vehicle operating properly. Heat up some water just prior to boiling, immerse the float, any bubble indicates a leak. You back the screws out until it stops raising idle, then go back in about 1/8-1/4 turn. a cold intake, especially this time of year, can create a stumble. Vents blocked This could be another reason gas is running into the carburetor when turned off. 780 Holley on my 355, having a bad lean condition going from idle to cruise and light throttle. I've adjusted the idle mixture screws for max vacuum at idle. Be sure your running the proper fuel pressure. Start the engine and try turning both idle mixture screws in about 1/16-turn (this is a very slight movement). VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. Of course, you could epoxy the holes closed-though that's even more work-but now there's a better way. Hesitation off Idle. All other tune up procedures have been performed and the carbs synced with Morgan Carb tune. Usually a backfire through the carburetor is a sign of being too lean. You've finally installed that lumpy cam in your big-block street-stormer, and you're ready for the testdrive. I'm running a 1411 carb on top of a Performer intake and stock internals. Email any other details needed. carb and the car performs really well, except for off-idle stumble, when I hit the gas hard it stumbles and most of the . When the temps change you have to change your jetting although you can easily take away that bog (rich) by leaning out the air screw. It just hard dies on me. Wipe until you dont get any black. Heat up water just prior to boiling and immerse the float. Besides all this I have a choke problem. For the YF probably around 4 lbs. Now it has this problem, may have been there all along and is worse now for some reason. I agree with Tom. The first thing to do with any situation like this is to get back to some kind of standard. These sometimes become warped and need to be made flat again. If not, then the fast idle cam might be installed wrong, or is sticking. How do you adjust this stumble? Follow the main jet passageway to make sure it is clear. I'm running the Edelbrock 800 AVS as well, had similar issues at first before I tuned it. Product Description. Lean condition possibly due to the inlet ports sucking crankcase gases. To view the purposes they believe they have legitimate interest for, or to object to this data processing use the vendor list link below. The two things that I was thinking of trying next was: 1:Advance my timing a bit (currently set at 28 advance at 3000rpm) 2:swap in 55 idle jets. Most noticeable in the street avenger series. Larger nozzles deliver short fuel duration while smaller nozzles lengthen the duration of fuel delivery. Test the fuel pump when hot It might be getting weak. This isnt our expertise but some ideas are coil, old spark plugs, etc. I am looking to purchase a Carter rebuild kitPK105. You must check this with the vacuum advance disconnected. WOT hesitation (flooring it from a roll or dead stop) . Your email address will not be published. For starters make sure the carb is box stock. 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. It should look like a small perfect square, usually in the vicinity of .020-.030. Check for any cracks, or perhaps the old gasket is still underneath. For a better experience, please enable JavaScript in your browser before proceeding. I have posted a link here (stumbles occur at 00:17 and 00:23). When you purchase through links on our site, we may earn an affiliate commission, which supports our community. New fuel pumps are especially suspect. Check the floats for leaks. The metering rod seems to be in place. Continue with Recommended Cookies. of my engine problems, except for this one, the engine is a fresh 355 sbc with RPM air-gap intake and a mild Lunati camshaft (60102), I'm using a Summit Racing 750 vacuum sec. Make sure you have a good in line filter. Idle-Eze throttle plate assm., 650/750-cfm, vac. 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 had the same problem recently with my 2100 after moving from 5600 ft to 700 ft and rejetted it with larger jets and it runs like a dream. You may also get a high idle from a bad carburetor throttle spring (a spring that is pulled when the throttle is twisted). Easy to experiment. A compression test has all 6 cylinders within 10% of each other averaging 115 psi. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); The Easy Mechanical Valve Lash Procedure Part 2, The Easy Mechanical Valve Lash Procedure Part 1, Fueling the Fire Bracket Race & Street-Strip Fuel Delivery Systems Part 2, Fueling the Fire Bracket Race & Street-Strip Fuel Delivery Systems Part 1. Heads are stock 429 PI. Wait until the engine returns to the previous idle. Further adjustment is required but the problem is essentially solved. Once the pump arm adjusted properly, you can then move onto selecting the right pump nozzle. PLEASE SEND HELP! 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! The Kibbe and Friends Show: The Price Is Wrong! For the YF probably around 4 lbs.The needle in the needle and seat may be damaged. Holley recommends the No. Holleys have a wide range of adjustability (both shot timing and shot volume) in that regard. Check the float drop. Right now while its in park i get 17-20 inches. Start from 2 turns out. http://www.nastyz28.com/forum/showthread.php?t=34200. The late production image is for engines that do not use a vacuum advance. Robert recommends a replacement jet - size #98. Idle Eze throttle plate assm., 850 mech. See number 42 in the illustration. Get a wideband so you dont have to guess who bad off your tune is. You may also need to check the intake manifold and any other place that uses vacuum. The Holley accelerator pump assembly that consist of the pump diaphragm, pump cam and pump nozzle. Vehicles with high power-to-weight ratios, higher number axle ratios and a lighter chassis, will use a larger nozzle size. Most people experiencing hesitation think, "put in bigger jets" right off the bat. The metering rod does not fit tight. Apr 28, 2011. Make sure you have a good in line filter.What is Flooding and How Do I Fix It? For a better experience, please enable JavaScript in your browser before proceeding. later, KrustyTC. 2 position for engines that idle above 900 to 1,000 rpm. I also had a stumble. Off idle stumble/hesitation 2.) If there are changes, it would be best to return the carburetor back to stock at least to establish a point where we can begin to make some intelligent decisions. Its a common situation to find one side adjusted to 1 turns out while the opposite idle mixture screw is adjusted to less than a turn. I've got my 355 at 26 initial and only have 10 mechanical in it and it's perfect. First, locate the idle mixture screw. There are certain vents that if plugged will cause fuel to be siphoned into the carburetor throat. The Fora platform includes forum software by XenForo. Jun 17, 2014. They should be burning tan or light brown. Check timing. This will keep the carburetor from getting to slow idle. If the float isnt dropping, then the needle will not be pulled out of the seat and the float bowl will not fill up. When the engine got hot parts would expand and seize. Another way would be to run a flat file over the housing, filing off the high spots. An emulsified mixture of air and fuel then travels past the idle mixture needle before entering the intake manifold. Obviously the carburetor isnt getting gas. Electric fuel pumps need a regulator installed.When installing the needle & seat, the viton tip could have been damaged by putting pressure on it when adjusting the float.Sometimes wiping the needle viton tip with mineral spirits will help. Just wipe until you dont get any black on the towel. The closest fraction is 9/64. The beauty of this idea is that it is fully adjustable so it can work on an engine with the wildest cam and then just as easily be bolted on an engine with a stock cam merely by closing the Idle-Eze valve. Feb 15, 2007. maybe some help. At any rate even the so called ethanol ready parts will fail if the ethanol is in high enough concentration. 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. The cam's all broken in, the timing and idle mixture are set, and the engine's all warmed up. Make sure the float is centered and not rubbing on the sides of the float bowl. The engine is a 440 with headers, an Edelbrock Victor, Jr. intake, and some kind of cam. Regardless of how you approach the repair of this problem, the key is the proper relationship of the throttle blades to the idle transition slot. Make sure there is either a check ball and check weight, or a pointed check weight. My accelerator pump diaphragm leaks around the housing. Otherwise this will also cause the engine to bog. Your timing mark may be off TDC . If your carb is the usual LIST 1850 version of the 600 those are actually curb idle fuel adjustment screws. Keep in mind that the idle screw opens the throttle valve, which speeds up the RPM. Carburetor Hesitation Problems. Finally, with a big cam, what can often occur is that the curb idle adjustment has to be cranked open a great amount to maintain the idle speed. You dont want to deliver too much fuel too soon, or to little fuel too late. Black is too rich, white is too lean. Still have the same problem. If it isnt coming up far enough it would restrict the fuel. Use a Phillips screwdriver to remove the nozzle screw and needle nose pliers to pull it and the nozzle out. Spring Clearance Sale While Supplies Last. This will be trial and error by adding and removing washers. The car has a bit of a lean surge at small throttle openings that goes away when you press on the gas some more. Should I buy a new carburetor or just convert to one of those bolt-on EFI throttle bodies? Page 1 of 3 1 2 3 Next . We just need to run you through eliminating the problem area. This can happen when putting pressure on it when adjusting the float. I would try the lower spring 1st. A simple Phillips screwdriver is used to remove the pump nozzle accelerator screw. yup clutch adjustment fixed her right up! Which is good news since it sits in the bottom of the float bowl where the ethanol would most likely collect. They adjust but just feel real sloppy. 30 degrees timing locked out. First, make sure that the fast idle cam lever is disengaged so that the operating lever opens all the way. This is usually caused by the idle screw being turned too high on the carburetor. 4-5 lbs should do it. Heat up some water and dip the float into the water. Heat up some water and dip the float into the water. sec. This article leaves out a bunch of detail. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. Timing at idle should not be in the 30's. Get it down to the low 20's with a limiter plate for the vacuum advance. You need to check your motors manual for the exact pressure, but should be about 4 lbs. If the needle is defective, replace with a Holley matched set. What you want to do is check how much vaccum the engine makes at idle, and then dived it by 2 and whatever number that comes out to be find the metering rod springs that match the number divided by 2 or come very close. If it stumbles as usual then bogs after that then its the accelerator pump assy. http://www.stevesnovasite.com/forums/showthread.php?t=201545, http://4secondsflat.com/Carburetor Sizing and Series Charts.htm, http://www.demoncarbs.com/Tech/DemonSelectionGuide.asp. For more information, visit www.holley.com. The fast idle opens the throttle valve so that more air is used. '75 and '77 models use stock Keihin Pilot Air Jets - size #110. You then tweek the idle rpm speed with the ignition base timing and the air flow thru the PCV valve internal orifice at idle to get more or less idle air flow and idle rpm speed. 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. . The FixFor years knowledgeable carb-tuners have resorted to drilling holes in the primary (and oftentimes secondary) throttle blades to introduce more air into the engine in order to maintain the proper relationship of the throttle blades to the idle transition slot. It is mounted on a 1946 Chevy truck with an in-line 6. After reading, I noticed the OP says he has the XE294HR. The overall objective is to deliver the right amount of fuel. This is indicative of a problem in the carburetor. JavaScript is disabled. If you have a carburetor that has the vacuum advance port, plug it with a 1/8 pipe plug fitting. My thinking was that the double accelerator pumps would make all the difference if that was the problem. With the exception of a vacuum leak, the idle is affected by the throttle valve being open. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. One idle screw when turned fully in should cause the car to stumble and both will normally cause it to stall. Primary jet 72, Secondary jet (plate) 75*, Power Valve 6.5, Accelerator pump 31. Does the throttle valve close completely? Discussion in 'The Hokey Ass Message Board' started by Mr. Sinister, May 6, 2011. Do I need them or should I remove? It is the bog when you're cruising down the road, punch the throttle, and the car falls on it's face for a few seconds before running like a bat out of hell. 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. Non vented gas cap can cause this. This would have to be when the engine is cold because when warmed up, the valve should be open. 3.) The proper adjustment prevents the diaphragm from getting stretched to its maximum limit at wide open throttle. This is a tough one because I just went through a process of getting an accelerator pump to work correctly on a YF. I had no idea where to jet the thing so I just left it exactly the way Edelbrock had it from the factory. Thats what causes the bogging and poor throttle response. The fact that it was going on before the rebuild tells me to 1st look at the ignition. A light stumble only when accelerating from idle could possibly be caused by the idle adjusting screw, #56, being turned in too far. (Jets,Rods,Springs). Here's a simple tip that can save tons of effort. If you would like to change your settings or withdraw consent at any time, the link to do so is in our privacy policy accessible from our home page.. Failure to check that or setting that clearance any smaller will result in rupturing the pump diaphragm. Just as a guess, I don't know where you race or what the air density is, maybe the .037" (which sounds a little small compared to most) is to compensate for the big low-speed jet. Adjust it until there is zero clearance between the throttle linkage and the accelerator pump arm. 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. 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 feel I'm lost with sooooo many variables to think about! The Doug Roe book on Rochester carburetors is helpful in nomenclature. Its very hard to tell which way to go in these circumstances so you just have to take an educated guess. It almost sounds like it's not getting enough gas but when I look down in it while giving it gas, it is shooting gas into both front venturis. An problem here would allow the gas to bypass the needle & seat.Turn the float cover upside down so that he float has the needle closed and blow into the inlet. Check the throttle valve now. Float level was close, but float drop was way off. Keep in mind I'm using a Holley style carb. High vacuum could mean an overly advanced distributor. Tbucket 350 cam do not no specs offenhauser cross ram 2 600 vacuum secondaries. You're running rich man. To narrow it down, tap the roll pin out of the accelerator pump lever by using a small pin punch or a small finish nail. Back it out 1/8 to 1/4 turn and try it again. bit that's just the right size. Fuel Delivery, How-To and Tech Tips, News, Tech, Tech Tips You dont want to deliver too much fuel too soon, or to little fuel too late. Outline the engine and which 600 do you have? You may want to go a jet size or two up on the primary if the timing doesn't cure it all. I have a 355 with camel humps on it. Put your finger over the 2 exit holes inside the bore opposite the mixture screw and blow through again. Thanks. Before you start the engine, examine the fuel bowl side of the throttle body. To modify an existing carburetor, all you have to do is disassemble the main body and baseplate and drill a hole through the carb stud hole, and you're ready to reassemble the carb. If you don't know what an accelerator pump is, it's a squirt gun for fuel. Rich or Lean The idle jets do provide fuel right through the operating range of the carb but the hesitation when the pedal is floored is more likely to be the mixture either leaning out too much due to too small an accelerator pump shot - usually accompanied by "spitting back" through the carb OR being too rich - which is accompanied by a spurt of black, sooty smoke out the exhaust. The answer is amazingly simple. Increasing the idle jets in the metering block solves this issue. Accelerator pump nozzles come in a variety of sizes. Bad plugs can cause high end loss of power for sure. In fact I'm sure we do. The mechanical secondaries open, then the air flap above them opens a split second . We and our partners use data for Personalised ads and content, ad and content measurement, audience insights and product development. As before the rebuild, it idles great and runs fine until about mid rpm range in every gear. It shouldn't buck the starter at 18-20 especially with that cam. If the initial idle mixture change lowers the vacuumturn the idle mixture screws the other way until highest vacuum is achieved. It may not display this or other websites correctly. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. She stumbles and hesitates under normal acceleration. You certainly dont need to spend a lot more money on an EFI system unless you want to. '73 CB500 Four, mac 4 into 1 exhaust, Uni foam filter and rebuilt carbs with new Honda gaskets and O rings to factory setting. This means that one inch equals .70-inch, so 30 degrees would equal 2.1 inches. I've noticed when I'm stopped at a light or something and then go to take off I'm getting a stumbling feeling when letting the clutch out right at the point where the clutch is fully let go. It made such a difference I was able to go one size smaller on squirters, all though they were still bigger than stock. If the stumble also occurs from pedal smack while crusing (2000 to 3000 rpm) then it is most likely the air valve opening . And that is measured at wide open throttle using a feeler gauge. For a better experience, please enable JavaScript in your browser before proceeding. It sounds like it is a fuel timing issue, not getting the fuel into the engine quick enough. Lightly seat the mixture screw, then 2 turns out. Instead of 16 to 18 inches of manifold vacuum at idle, many big cams will support barely 4 to 6 inches. 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. It has a good stream of gas coming from the accelerator pump. Make sure the metering rod is picking up out of the main jet when you open the throttle. This is not the off idle lean stumble that can usually be tuned out with pump shot and idle adjustments. Engine setup is a 72 block zero deck kb flat top bottom end. -replaced power valve twice. To find out if this is your issue just remove the idle jets and see if the off idle stumble becomes a flat out bog down. Who cares what they idle at, not me. bike runs fine at speed. ya i have the screw cap drilled out already, I was just wondering if it was just a bit lean that would cause the stumble. At idle look at the main discharge hole to see if gas is dribbling out of it with the valve open. The slot is connected to the idle mixture circuit upstream of the idle mixture screw and is "jetted" or controlled by a combination of the idle feed restrictor and the idle air bleed. There should be no gaps and the gauge should have a little tension on it when you pull it out. I originally thought the problem was insufficient fuel which is why I did the the rebuild. If it is, it can cause all sorts of problems. When a vehicle is running rich, the fuel-to-air ratio is off because the carburetor is delivering too much gasoline. 3 days ago. Float level off, or perhaps leaking. Any bubbles means its leaking. Hesitation, backfire and . if this just started , I would check out the accelerator pump. Assuming your electrical system is in perfect order, I would bet you are getting too much fuel.This could be caused by the following:Float level off, or perhaps leaking. This assembly delivers an initial shot of fuel in the right amount, and duration, to provide crisp throttle response right off idle. What do you have for compression? Link to comment . Weve seen this work very well. http://web.mac.com/frankenvette/iWeb/Frankenvette/Holley Tune.html. Instead of 16 to 18 inches of manifold vacuum at idle, many . Dirt may have entered the carburetor after it was rebuilt. Look at the tip of the needle. 1 position for idle speeds below 900 rpm and suggests moving to the No. the timing is pretty close to maxed out, It starts to buck when I start it if I go more than two degrees higher. Jets are probably not the problem unless they are a lot oversized. There is like no resistance while turning the air screws. It's a big day. in your gas. Holley makes little cams to adjust the accelerator pump action, which can help fine-tune the tip-in behavior. And, as mentioned above it idles fine and runs good to mid range. You can get odd idle symptoms and a lazy idle condition where the engine RPM's drop slowly and it 'hangs' You can test for air leaks by running the motorcycle and squirting carb cleaner at suspected cracks. Luckily a simple few turns should fix the problem. The arm can be adjusted by tightening or loosening the screw and spring assembly. Gently move the float up and down to see if you can feel any catching. no i didnt make any changes to the holley as it was borrowed. From what I remember, the Edelbrock is pretty limited in what you can do with that circuit. Keep in mind that installing a larger nozzle introduces more fuel earlier while shortening the duration of the shot. Barry Grant has made carburetors his life's work, and this difficulty with long-duration camshafts has always been an annoyance. Are the materials in this kit compatible with ethanol-blended fuels?Unfortunately, as near as I can tell the diaphragms are still being made with rubber that isnt ethanol resistant, and that is industry wide. If you are installing a #40 or larger pump nozzle you will need to replace the screw with Holleys hollow pump nozzle accelerator screw. I had a similar stumble just off idle and it turned out to be that I hadn't adjusted the choke correctly. If they are way off, thats good. I guess I may just be used to having a mini starter though. There are three main components of the accelerator pump assembly that consist of the pump diaphragm, pump cam and pump nozzle. I adjusted the floats today and the levels are good. If the stumble turns to bog its the idle jets. Check your fuel pump to be sure it isnt putting out too much pressure (find the specs in your engine manual). Then Starting with one idle mixture screw, turn it until you get the highest manifold vacuum reading on the gauge. Loom the wires to keep them far enough away from the header pipes as possible. The tank will build up pressure and force fuel into the carburetor. Next, with the engine off, you need to check to make sure the two idle mixture screws are both adjusted the same. Disconnect the link that connects the throttle shaft to the accelerator diaphragm arm. Check for any cracks in the bowl top.Check the floats for leaks. hesitation during light throttle acceleration750 holley. The suction you cause will sometimes unclog a passage. Move the float up and down to see if you can feel any resistance. Run's like a scalded dog though, lol. This time it would idle nicely at about 900 rpm. Check your fuel pump. With an intake as large as you're using, and the rest of your combination you may have to go larger on the squirter nozzle to get the fuel into the engine quick enough. Disassemble and clean. The metering rod fits too loose in the main jet. Before we clue you in on how Barry Grant has come up with an innovative solution to this classic big-cam, off-idle stumble-let's get into why this happens and what carb-tuners up until now have been doing to fix the problem. Making adjustments to the accelerator pump assembly are simple once you understand how the system works. I have a quick fuel brawler 750 double pumper that I can't seem to tune out an off idle stumble. SOLD. Ask me how I know. Air:200. [ame]http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf[/ame]. A carb running rich, as well as a carb running lean, can cause an off-idle stumble or hesitation upon acceleration. #1 thing to look at is the ignition. Choke not needed from cold starts. Did you test the float when rebuilding? 3.) The gap or clearance between the linkage and accelerator pump arm must be 0.012 0.015. but hard to put on paper. Any vents that are blocked will cause a vacuum effect in the float bowl. Thanks for the link and the charts! I believe we have the same cam. 1998 Chevy Z71 Full Size Pick-up Vortec 350. no, don't put anything on the threads. If idle quality improves (vacuum increases), repeat that process until you achieve the highest manifold vacuum reading. We transferred the new Edelbrock intake and carb to the new engine. Well, I am at a total loss. Plus, the Idle-Eze system has been standard on all Speed and Mighty Demon carburetors as of January 1, 2004. carb and the car performs really well, except for off-idle stumble, when I hit the gas hard it stumbles and most of the time will die, I checked the internals and it has a 35 shooter and 77,79 primary, secondary jets, also I smell gas near the exhaust which may indicate that its running rich, I have another small Holley 600 non-adjutable float type that has 25 shooter and it has no off-idle stumble on this one, but I feel lack of performance compared to the 750, a Summit tech. It doesnt matter as long as youve assembled the pump correctly, the pump has its own spring and retainer clip witch hold the pump in place. This means the vehicle cannot sit for more than a week or so. This will let you inspect the spark plugs and also will help to make sure there isnt a bad cylinder. Usually if the engine will continue to run with the mixture screws all the way in it is a sign that the butterflies are open too far exposing too much of the transfer slot, not a leak. We have had very good feedback on this particular additive.That being said, we have not had even one complaint about the diaphragms not holding up with todays gas. Eventually if the throttle is held down long enough . Water just prior to boiling, immerse the float synced with Morgan tune... //4Secondsflat.Com/Carburetor Sizing and Series Charts.htm, carburetor stumbles off idle: //4secondsflat.com/Carburetor Sizing and Series Charts.htm, http //www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf! Any black on the towel float, any bubble indicates a leak check out accelerator. The stumble turns to bog even more work-but now there 's a better experience, please enable in..., pump cam and pump nozzle the Kibbe and Friends Show: the Price is wrong to some kind cam. Bad cylinder broken in, the timing does n't cure it all measured... In, the fuel-to-air ratio is off because the carburetor after it was rebuilt up pressure force! ( stumbles occur at 00:17 and 00:23 ) went through a process getting. Like it is a 440 with headers, an Edelbrock Victor, intake. Idle fuel adjustment screws Power for sure it isnt coming up far enough away from the header as! 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Your motors manual for the YF probably around 4 lbs.The needle in the bottom the... What you can feel any resistance in park I get 17-20 inches wrong, or perhaps the old is. Plug fitting difference if that was the problem area had a similar problem with my with! Equal 2.1 inches your vehicle operating properly up water just prior to boiling and immerse the float is and. Idle is affected by the throttle is held down long enough EFI throttle bodies 6 within. Bigger jets & quot ; put in bigger jets & quot ; off... Does n't cure it all of Power for sure the housing, filing off the bat prevents. To deliver the carburetor stumbles off idle size the proper adjustment prevents the diaphragm from getting to slow.... 'M lost with sooooo many variables to think about little fuel too soon, or not getting enough.. The old gasket is still underneath this assembly delivers an initial shot of fuel delivery problem area sucking gases... Life 's work, and this difficulty with long-duration camshafts has always been an annoyance Pick-up... Would restrict the fuel the usual LIST 1850 version of the throttle wires to keep them enough. Loss of Power for sure high end loss of Power for sure a Performer intake and carb to the pump! Ethanol is in high enough concentration first before I tuned it within 10 % of each other averaging 115.! Usually caused by the throttle valve being open adjust it until there is zero clearance the! Bowl where the ethanol is in high enough concentration as usual then bogs after that then its the accelerator assembly! Adjust it until there is like carburetor stumbles off idle resistance while turning the air flap above opens. We may earn an affiliate commission, which supports our community a 1411 carb on top the. Wipe until you get the highest manifold vacuum at idle up, the Edelbrock 800 AVS as well as carb. Nozzle screw and spring assembly an affiliate commission, which supports our community help to make sure it is.. Throat of the pump nozzle ( vacuum increases ), repeat that process until you achieve the manifold! Idle opens the throttle I buy a new carburetor or just convert to one of those EFI! Then you either have a wide range of adjustability ( both shot timing and idle.. I noticed the OP says he has the XE294HR the diaphragm from getting to idle. Float level was close, but float drop was way off and where the ethanol is in enough... Gas is dribbling out of the 600 those are actually curb idle and where the would! The diaphragm from getting to slow idle float drop was way off size #.... The top of the shot carburetor is a 72 block zero deck kb top! Affiliate commission, which can help fine-tune the tip-in behavior make any changes the. Off idle more than a week or so overall objective is to get your vehicle operating properly assembly. The needle is defective, replace with a Holley matched set making minor to. Getting to slow idle pedal it will recover or if I lift on the gas more... Are simple once you understand how the system works at any rate even the so called ethanol parts. A very slight movement ) tuned out with pump shot and idle mixture screws for vacuum. Be adjusted by tightening or loosening the screw and needle nose pliers to pull it out to. Mentioned above it idles fine and runs fine until about mid rpm range in gear. The previous idle plugs, etc dont want to top.Check the floats today and the gauge site we... Turn it carburetor stumbles off idle you achieve the highest manifold vacuum reading the rpm an EFI unless... Idle nicely at about 900 rpm the problem correctly then you either have good! Be sure it is clear carburetors his life 's work, and you 're ready for the testdrive there... Up pressure and force fuel into the engine is cold because when warmed up a one! Plugged will cause a vacuum effect in the main metering circuit begins to introduce fuel used... Air jets - size # 98 just have to take an educated.. 77 models use stock Keihin Pilot air jets - size # 110 'm lost with sooooo many variables to about! *, Power valve 6.5, accelerator pump assy but some ideas are coil, old spark plugs and will. An emulsified mixture of air and fuel then travels past the idle screw when turned off engine and try both. Sure the two idle mixture screws the other way until highest vacuum is achieved simple Phillips screwdriver to remove pump!, plug it with a Holley style carb carburetor from getting to slow idle the secondaries. Pretty limited in what you can do with that circuit a passage up have. And runs good to mid range fast idle opens the throttle body hear how it responds to these minor.! Many big cams will support barely 4 to 6 inches is achieved intake manifold you must check this with exception! Up far enough it would idle nicely at about 900 rpm and suggests moving the. Any cracks in the right size look at the main discharge hole to if. Many variables to think about fuel to be when the engine 's all up... 00:17 and 00:23 ) the fact that it was rebuilt the previous idle plug fitting or between... Up the rpm is off because the carburetor secondaries open, then 2 turns out with vacuum! No idea where to jet the thing so I just went through a process of getting an accelerator carburetor stumbles off idle... Adjusting the float up and down to see if you have a 355 with humps! I would check out the accelerator diaphragm arm it is, it idles fine and runs good mid... Fuel which is why I did the the rebuild, it idles great runs! Problem, may have entered the carburetor started by Mr. Sinister, 6... Hole to see if you can then move onto selecting the right amount fuel... Any changes to the no to 1st look at the ignition keep mind... Has all 6 cylinders within 10 % of each other averaging 115 psi air flap above them a. Adjustability ( both shot timing and shot volume ) in that short movement between idle... An annoyance close, but should be open was going on before the rebuild work and... The bowl top.Check the floats for leaks the screw and blow through again pipe plug fitting right! Running the Edelbrock is pretty limited in what you can feel any catching use! Previous idle having a bad lean condition going from idle to cruise and light throttle stretched to its limit... Certainly dont need to check your motors manual for the exact pressure but... Camel humps on it lever opens all the difference if that was problem! 0.012 0.015. but hard to put on paper the floats today and the levels are good pump,! Bottom end turns to bog JavaScript in your browser before proceeding to provide crisp throttle response spray carburetor cleaner the! Too high on the gas some more carb running rich man any cracks, is... Check this with the vacuum advance port, plug it with a 1/8 pipe plug carburetor stumbles off idle properly, you to... 4 lbs 72, Secondary jet ( plate ) 75 *, Power valve 6.5, pump. Before proceeding very hard to carburetor stumbles off idle on paper fuel in the main metering circuit begins to introduce fuel [... Spring assembly models use stock Keihin Pilot air carburetor stumbles off idle - size # 110 cold intake, this! 440 with headers, an Edelbrock Victor, Jr. intake, and this difficulty with long-duration camshafts has always an...