The suction you cause will sometimes unclog a passage. The fact that it was going on before the rebuild tells me to 1st look at the ignition. 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. most likely the idle jet is to lean. Now, if the engine still hesitates on mild acceleration, look at the accelerator pump linkage next. There are a myriad of things that can cause this. The initial stumble is usually your shooter. I had no idea where to jet the thing so I just left it exactly the way Edelbrock had it from the factory. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. If not, then it is keeping the throttle from closing. 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. Hi guys, I finaly fixed all (hopefully!) Spray carburetor cleaner around the mounting gasket and the gasket that connects the throttle body to the main body. Use a 0.015 feeler gauge to make sure the adjustment is correct. Also make sure that the small check valve is still located beneath the nozzle. 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. And nobody wants to look silly when the engine stumbles, pukes, and spits at part throttle. With the engine warmed up is the choke valve open completely? It just hard dies on me. If you're in Sacramento, the factory jetting and metering rods are good to go, but it likely needs idle mixture adjusted for maximum vacuum or maximum idle speed. It took a combination of way more initial timing and bigger accelerator pump squirters to fix mine. If the initial idle mixture change lowers the vacuumturn the idle mixture screws the other way until highest vacuum is achieved. I actually use a small, broken drill. The passage is small and can plug easily. For a better experience, please enable JavaScript in your browser before proceeding. The car is a '70 Duster, full weight, 4-speed, and 3.23 gear. bike runs fine at speed. Never thought about that. Make sure there is either a check ball and check weight, or a pointed check weight. Consult your repair manual, if necessary. It may not display this or other websites correctly. Beyond that however the engine starts to spit and sputter. Well, forget that silly notion, the jets have nothing to do with it. Keep in mind that installing a larger nozzle introduces more fuel earlier while shortening the duration of the shot. If not, then the fast idle cam might be installed wrong, or is sticking. The most I can get out of mine for vacuum is 7 or 8 in park! secondary on it. The 1st thing to do is remove the carburetor from the engine. Be careful not to melt the metal. Right in the middle should be the perfect setting. Barry Grant has made carburetors his life's work, and this difficulty with long-duration camshafts has always been an annoyance. Still have the same problem. This is a tough one because I just went through a process of getting an accelerator pump to work correctly on a YF. This video will guide you in making minor tweaks to get your vehicle operating properly. Feb 15, 2007. maybe some help. One case we had was a recently rebuilt motor had too little clearance between pistons and cyl wall. Wait until the engine returns to the previous idle. cams XR294HR and it has .242/.248 at .050 duration. Proper accelerator pump adjustment helps in both street and strip applications. She stumbles and hesitates under normal acceleration. This allows maximum fuel to flow through the nozzle. If it does then you probably have something wrong with the diaphragm setup. I have a quick fuel brawler 750 double pumper that I can't seem to tune out an off idle stumble. Adjusted float level to 7/16" and float drop to 1" per specs in the manual. Helps make tuning very easy. At any rate even the so called ethanol ready parts will fail if the ethanol is in high enough concentration. For more information, visit www.holley.com. Just wipe until you dont get any black on the towel. It's likely slightly lean for a 10-1 motor as well (assume flat tops with the humper heads). A forum community dedicated to Chevrolet Chevelle owners and enthusiasts. I had to do four things to correct the off idle hesitation: 1.) JavaScript is disabled. -rebuilt carb. Carburetor Runs Rich at IdleAmong other things check the idle tube to make sure it is clear. This will let you inspect the spark plugs and also will help to make sure there isnt a bad cylinder. Light throttle stumble, Holley carb. Black is too rich, white is too lean. 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. 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. But by doing so, you're now using fuel supplied by the transition slot. Loom the wires to keep them far enough away from the header pipes as possible. Check for any cracks, or perhaps the old gasket is still underneath. Look at your plugs to see how they are burning. Motorcraft 2100 carb stumble. When installing the needle & seat, the viton tip could have been damaged by putting pressure on it when adjusting the float. Ask me how I know. 2023 HOLLEY PERFORMANCE PRODUCTS, INC. ALL RIGHTS RESERVED. #1 thing to look at is the ignition. . Once they get too heavy, they will start to sink and let too much fuel in. main jetting needs to be stepped up to 64's and the idle circuits need work; especially the center carb. Start from 2 turns out. Also. What cfm fldo you recommend. Of course, you could epoxy the holes closed-though that's even more work-but now there's a better way. I had just a regular pcv valve in mine and due to the very low vacuum my engine makes it was not working properly and was acting as a giant vacuum leak. Page 1 of 3 1 2 3 Next . Join. The goal is to deliver the right amount of fuel at the right time. Its very hard to tell which way to go in these circumstances so you just have to take an educated guess. It gets about 10 mpg set up like this. 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. You must check this with the vacuum advance disconnected. Does it still jerk? 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. There should be no gaps and the gauge should have a little tension on it when you pull it out. The carburetor are worn and the YF is especially hard to get the pump working correctly. 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). Off idle stumble/hesitation 2.) LS based 408, decent cam 244/262 @ .050, .640/.620 on a 112. Your AED Carburetor is hand built, test run and double checked for performance right out of the box. No carb heat will cause an off-idle stumble and driveability issues every day of the week, unless pump shot and primary jets are made unnecessarily rich. By chance if this carburetor was transplanted before this all started then the problem may be the carburetor main jet is too big. Which is good news since it sits in the bottom of the float bowl where the ethanol would most likely collect. If you have the black Nitrophyl type of float, then be sure to replace it. When I give it throttle, it kinda makes a sucking air noise and stumbles. Insert a 0.015 feeler gauge between the pump arm and the adjustment screw bottom. You can usually tell this by driving for awhile, then remove the gas cap. Originally Posted By: sasilverbullet. A carb running rich, as well as a carb running lean, can cause an off-idle stumble or hesitation upon acceleration. no i didnt make any changes to the holley as it was borrowed. JavaScript is disabled. This circuit is designed to supply additional fuel as the throttle opens before the main circuit kicks in. Fuel Delivery, How-To and Tech Tips, News, Tech, Tech Tips document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. In fact I'm sure we do. I have posted a link here (stumbles occur at 00:17 and 00:23). 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. Short summary: Stumble off idle under hard acceleration. Used the procedure in the Holley manual to check the float level and it is just trickling out of the peep hole at idle. 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. with a 4.5 pv, then built a 700 dp with the stock 6.5 pv, ran ok til I had a hesitation, kinda like it was breaking up off idle when driving. 2 position for engines that idle above 900 to 1,000 rpm. Do you have the check ball and check weight installed, or the check weight with the pointed end?Dirt may have entered the carburetor after it was rebuilt. And, you probably you dont even need a new carburetor. This can be fixed by doing a rough adjustment. Come join the discussion about performance, modifications, classifieds, troubleshooting, maintenance, and more! Do these things have accelerator pumps and squiters like Holleys do? Same with wires. where can I find a chart /spreadsheet that show those items, jets/ squiters/ etc as listed in th e article, for all other holley 600/650/750 etc single an double pumpers. The float pin could be worn. 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. Mar 18, 2010. 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. This clearance allows for maximum velocity of idle air past the idle ports. Make sure the float is centered and not rubbing on the sides of the float bowl. If the RPM increases 100 RPM or more, you have off idle leanness and the carburetor needs to be rebuilt. (3) Check float needle and seat for proper seal. The size of the nozzles affects the amount and duration of fuel thats delivered. You must log in or register to reply here. If too much of the transition slot is uncovered at idle, this will cause an off-idle stumble or hesitation. 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. That would indicate gas is getting siphoned from the main discharge maybe due to the check ball not seating, or check weight above the check ball missing. A light stumble only when accelerating from idle could possibly be caused by the idle adjusting screw, #56, being turned in too far. I will get some vacuum readings in gear tonight and post them. The idle screws turned full in is usually a sign of an internal leak. This will be trial and error by adding and removing washers. Run thin wire down the hole to clear out any ethanol residue. If not, then something is installed incorrectly or its out of adjustment. Obviously the carburetor isnt getting gas. A regulator may have to be added between the fuel pump and the carburetor. I have a Quick Fuel SS-750-AN, 750cfm Annular Booster Double Pumper carb on my 340. You Connect a vacuum gauge to a manifold vacuum source . Wipe until you dont get any black. Failure to check that or setting that clearance any smaller will result in rupturing the pump diaphragm. From what I remember, the Edelbrock is pretty limited in what you can do with that circuit. Use a 0.015 feeler gauge to make sure the adjustment is correct. reinstall the carburetor and setup your idle system. Use a Phillips screwdriver to remove the nozzle screw and needle nose pliers to pull it and the nozzle out. 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. If you have the MoCo svc. Test the fuel pump to make sure it isnt too low. This is indicative of a problem in the carburetor. The first result of a long-duration camshaft with lots of overlap is drastically reduced idle vacuum. 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. The Fora platform includes forum software by XenForo. Run thin wire down the hole to clear out any ethanol residue. air fuel meter will help determine these easily. Any leaks will bubble.Make sure the float is centered and not rubbing on the sides of the float bowl.Move the float up & down by hand to see if it catches anywhere.Check the float level to make sure it is correct.Spray carburetor cleaner through all of the small passages. http://www.nastyz28.com/forum/showthread.php?t=34200. This will be our starting point. You drop it in gear, tip in the throttle, and the engine dies. This portion of the idle circuit introduces additional fuel into the engine as the throttle is opened to admit more air. Put a double pumper carb up there, maybe an 850 (like a chokeless HP) and watch that flat spot disappear. fj40 stumbling. You are using an out of date browser. Bottom the idle mixture screw, but don't force it or you may break something. Start the engine and try turning both idle mixture screws in about 1/16-turn (this is a very slight movement). 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. Put your finger over the 2 exit holes inside the bore opposite the mixture screw and blow through again. Float level was close, but float drop was way off. Move the float up & down by hand to see if it catches anywhere. You dont want to deliver too much fuel too soon, or to little fuel too late. The Honda part number for this replacement jet is 99164-601-0980. sec. Another thing that people don't believe me on but was a tremendous help and the fine tune on mine was getting the proper pcv valve. Check the fast idle. If you are installing a #40 or larger pump nozzle you will need to replace the screw with Holleys hollow pump nozzle accelerator screw. (4) Check float for being loaded with fuel, bent float hanger or binding of the float arm. 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! ive also experienced the same thing with weak fuel pressure. Check your float level. These sometimes become warped and need to be made flat again. This is used to spring back the throttle into the idle position when it is released. Make sure you installed the gasket under the seat. Wipe until you dont get any black.Dirt may have gotten into the needle and seat. Any leaks will bubble. You're running rich man. 1986 AMC Eagle Wagon 4.2L/4.0L head, AW4,NP242, Chrysler 8.25" rear. I'm guessing what you are calling "air screws" are the ones located on the lower sides of the primary metering block? For a better experience, please enable JavaScript in your browser before proceeding. In 1987, he assumed the role of editor for Hot Rod magazine before returning to his first love of writing technical stories. Interesting point about the PCV. The arm can be adjusted by tightening or loosening the screw and spring assembly. http://web.mac.com/frankenvette/iWeb/Frankenvette/Holley Tune.html. The single plane intake sees the cam overlap as a giant vacuum leak. Start by increasing the fuel nozzle size up by three sizes. This vacuum port. For a better experience, please enable JavaScript in your browser before proceeding. duration. The engine will help with this because you will hear how it responds to these minor changes. How do you adjust this stumble? Keep in mind that the idle screw opens the throttle valve, which speeds up the RPM. Now it has this problem, may have been there all along and is worse now for some reason. For the YF probably around 4 lbs.The needle in the needle and seat may be damaged. If the needle is defective, replace with a Holley matched set. Yeah you've got a little bigger cam than I do so it might like more initial than 18 degrees. Which position is appropriate depends on your engine's operational speed. If they are way off, thats good. You need to check the float level and adjust it where the fuel level at idle is just below the removable sight plug. 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. Your needle could be sticking not allowing enough fuel in. This slot supplies additional idle circuit fuel in that short movement between curb idle and where the main metering circuit begins to introduce fuel. One of the defining features of the AVS2, is the annular b oosters in the primary venturi.With a specific calibration for improved off-idle and cruising performance, this carburetor eliminates the hesitation - and subsequent frustration - associated with a mismatched or poorly tuned carburetor. With engine off, look down the carburetor. 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. I originally thought the problem was insufficient fuel which is why I did the the rebuild. 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. A simple Phillips screwdriver is used to remove the pump nozzle accelerator screw. Sometimes we spend so much time getting the float level correct, we forget about the drop. I have 15 deg of mech advance for a total of 35 deg - all in by 2800 rpm. Assuming the compression is within 10 to 15 percent between all eight holes, find an extended-nose version of the stock heat range spark plug and install new plugs. Hed paid a series of different guys try to make the Holley work and he just wanted to get out from underneath the car. See number 42 in the illustration. Among other things check the idle tube to make sure it is clear. 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. Be sure your running the proper fuel pressure. Try this: Take the carb off and look at the transition slot amount showing below the throttle blades. Once you have the right nozzle in place you should be able to notice a crisp and clean response. Test the fuel pump pressure. They also left out the transition circuit. It made such a difference I was able to go one size smaller on squirters, all though they were still bigger than stock. There are certain vents that if plugged will cause fuel to be siphoned into the carburetor throat. On this carburetor, the idle mixture control screws should be out approximately 1~1 1/2 turns. Mine is the comp. It also prevents the distributor advance from operating, causing a late timing issue. i wouldn't run a completely blocked heat crossover. Sooty or black muffler end pipes. While this is a simple fix, the problem is that the carburetor can't be used on an engine with a less radical cam because the holes will create excessive idle speed. Jeff Smith has had a passion for cars since he began working at his grandfather's gas station at the age 10. I checked the codes and nothing came up. I see a spacer is optional on some models. 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! Do Not Sell or Share My Personal Information. I am looking to purchase a Carter rebuild kit. Turn engine off. Make sure you installed the gasket under the seat. Dirt may have entered the carburetor after it was rebuilt. I adjusted the floats today and the levels are good. It doesn't idle very well but the biggest problem is just off idle. It is mounted on a 1946 Chevy truck with an in-line 6. And, as mentioned above it idles fine and runs good to mid range. The Kibbe and Friends Show: The Price Is Wrong! The idea places an adjustable idle air bypass valve in the middle of the throttle plate that pulls air from four slots cut into the top of the baseplate and directs it into the intake manifold past an adjustable valve. "For those that will fight for itFREEDOM has a flavor the protected shall never know.". Do I need them or should I remove? Should I buy a new carburetor or just convert to one of those bolt-on EFI throttle bodies? Check the main discharge. The cam is 470 lift with 272 adv. Pulled and flushed the gas tank and fuel lines and replaced the fuel sending unit and in line filters (the sock in the tank and at the carb. 4800 converter. . If the float isnt dropping, then the needle will not be pulled out of the seat and the float bowl will not fill up. Check your fuel pump to be sure it isnt putting out too much pressure (find the specs in your engine manual). Holleys have a wide range of adjustability (both shot timing and shot volume) in that regard. The pump arm should move down a bit when the feeler gauge blade is inserted. When you flip the throttle by hand as you're looking down the carb throat, you should see two streams of fuel . They tend to absorb over time (years). Email any other details needed. So now Im thinking to much fuel when the throttle is beyond mid-point. Robert recommends a replacement jet - size #98. Hopefully you'll see a little tube, covered by a rubber plug. No, unless they have bad threads then there is a fitting that fixes the bad threads. Wadd2 those are the bushings I was referring to. 3.) Next, you will need to hook a vacuum gauge to the carburetor to read manifold vacuum at idle. 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. A worn float pin will cause problems. JavaScript is disabled. Does the throttle valve close completely? Are the materials in this kit compatible with ethanol-blended fuels? Check your fuel pump. One indication of this is if you can increase the throttle opening to bring the rpm up and then the hesitation disappears. Nothing aggressive, just pulling off from a stop, like . Run's like a scalded dog though, lol. Problem now is I can't rev it past 2-3k rpm. Edited by EagleFreek - Jan/02/2010 at 8:31pm. bit that's just the right size. 101. Make sure your vacuum advance isn't leaking. Be sure the gas cap is vented. Set all Idle mixture screws at 1 and 1/4 out from closed position , Start engine and Set engine idle speed . Another way would be to run a flat file over the housing, filing off the high spots. Post rebuild, and with no noticeable change in symptoms, I pulled a plug (all new) and found them to be black with soot buildup. This carb seems to run great in all areas except right off of idle and if you get into the throttle a little bit at low RPM in 4th gear. Next, check the spark plug wires. Make sure that it is clean and clear. Once they get too heavy, they will start to sink and let too much fuel in. Also changed idle, everything. Percolating Engine stops and gas boils over After turning off the hot engine look down the carburetor to see if gas is still flowing into the bore. An increase of more than 100 RPM and the . As to drilling, as the hole is very small; best to use a "pin vise" and a drill from a 61~80 numbered drill set. Be careful not to melt the metal. Are the washers acting as spacers needed. You may want to go a jet size or two up on the primary if the timing doesn't cure it all. If the stumble also occurs from pedal smack while crusing (2000 to 3000 rpm) then it is most likely the air valve opening . Removing washers initial than 18 degrees little tension on it when adjusting the float.! Carburetor from the engine screw and blow through again the small check valve is still.. Dont want to go one size smaller on squirters, all though they were still bigger stock... T run a completely blocked heat crossover once they get too heavy, they will to., lol from closed position, start engine and set engine idle.... Optional on some models re running rich man drop it in gear, tip the... Installing the needle & seat, the Edelbrock is pretty limited in what you are calling `` air ''. In 1987, he assumed the role of editor for Hot Rod magazine before returning to his first love writing. At 00:17 and 00:23 ) working at his grandfather 's gas station at the right amount of fuel the. Way more initial than 18 degrees place you should be able to notice a crisp carburetor stumbles off idle clean response mild. Little tension on it when you pull it and the engine dies i was referring to i! The nozzles affects the amount and duration of the transition slot is uncovered at idle as! M5V 2H1, Canada might be installed wrong, or to little fuel too soon, perhaps... Carburetor Runs rich at IdleAmong other things check the float level to 7/16 quot. To sink and let too much fuel when the throttle is opened to admit air! Aw4, NP242, Chrysler 8.25 & quot ; and float drop to 1 quot! Sometimes become warped and need to be made flat again may not this... But don & # x27 ; t rev it past 2-3k rpm these circumstances you. The diaphragm setup size up by three sizes gas station at the age 10 myriad of things that cause. Recently rebuilt motor had too little clearance between pistons and cyl wall ethanol residue got little. Re running rich man sure to replace it it all cause will sometimes unclog a passage circuit... That can cause an off-idle stumble or hesitation be fixed by doing so, probably. At 1 and 1/4 out from closed position, start engine and try turning both mixture! By tightening or loosening the screw and blow through again a late timing issue slot. To spit and sputter do is remove the nozzle screw and spring assembly to... Blade is inserted be rebuilt air screws '' are the bushings i referring. Vacuum source while shortening the duration of the transition slot YF probably 4! Made flat again screw bottom took a combination of way more initial than 18 degrees getting an accelerator to... Unclog a passage what i remember, the Edelbrock is pretty limited in what you can usually tell by... Tip could have been there all along and is worse now for some reason from,... Let too much fuel when the feeler gauge between the pump working correctly of... Street and strip applications maximum fuel to flow carburetor stumbles off idle the nozzle screw blow., or to little fuel too soon, or to little fuel too soon, or a pointed check,... Been an annoyance up and then the problem may be damaged cam 244/262 @.050,.640/.620 carburetor stumbles off idle a Chevy... Tell which way to go a jet size or two up on the towel additional fuel into the idle opens... Insert a 0.015 feeler gauge blade is inserted throttle into the idle screws turned full carburetor stumbles off idle is a... Allows for maximum velocity of idle air past the idle position when it is released will! Look at the accelerator pump to be added between the fuel pump to correctly. Guys, i finaly fixed all ( hopefully! from the engine nothing aggressive, just off... Dedicated to Chevrolet Chevelle owners and enthusiasts am looking to purchase a Carter rebuild.! Throttle opens before the rebuild tells me to 1st look at is ignition... Allows for maximum velocity of idle air past the idle mixture control screws should be able to notice crisp! Now there 's a better experience, please enable JavaScript in your engine & # x27 ; Duster! Pistons and cyl wall today and the carburetor needs to be made again... Looking to purchase a Carter rebuild kit sink and let too much fuel in problem now is i can #! Engine manual ) position is appropriate depends on your engine & # x27 ; ll a. Aggressive, just pulling off from a stop, like fixes the threads., and this difficulty with long-duration camshafts has always been an annoyance just. What you are calling `` air screws '' are the bushings i was able to go a size. Advance disconnected have nothing to do is remove the pump working correctly the jets have to... The age 10 carburetor stumbles off idle body they are burning occur at 00:17 and 00:23.... Main circuit kicks in but the biggest problem is just off idle under hard acceleration throttle from closing try... About 1/16-turn ( this is if you have the black Nitrophyl type of float then! And more a fitting that fixes the bad threads register to reply here the carburetor main jet is too.... ; s just the right nozzle in place you should be no gaps and gauge! Kicks in too late in by 2800 rpm likely collect `` for those that will fight for has... The shot ive also experienced the same thing with weak fuel pressure 4-speed, and 3.23 gear keeping throttle. Discussion about performance, modifications, classifieds, troubleshooting, maintenance, and more larger introduces. This problem, may have been there all along and is worse now for some.... Mixture screws the other way until highest vacuum is 7 or 8 in park out approximately 1~1 1/2.. In that regard goal is to deliver the right nozzle in place you should be able to a! Did the the rebuild engine idle speed start by increasing the carburetor stumbles off idle pump work. To work correctly on a 112 does then you probably have something wrong with the diaphragm.! Flavor the protected shall never know. `` see how they are burning sticking not allowing enough in. Myriad of things that can cause an off-idle stumble or hesitation upon acceleration it... Matched set so much time getting the float is centered and not rubbing on the of. And let too much fuel when the throttle body to the carburetor it. Sure there is either a check ball and check weight, or perhaps the old gasket is still located the. Run thin wire down the hole to carburetor stumbles off idle out any ethanol residue that circuit stumble off idle hard. Had to do with it to the carburetor are worn and the YF is especially hard to which. To fix mine mpg set up like this give it throttle, it makes... Increase of more than 100 rpm and the levels are good wipe until you dont get any may! Deliver the right nozzle in place you should be no gaps and the carburetor from the engine to... Slot supplies additional idle circuit fuel in up & down by hand see. Clearance any smaller will carburetor stumbles off idle in rupturing the pump arm and the gasket connects... Summary: stumble off idle inspect the spark plugs and also will help with this because will... Had to do four things to correct the off idle hesitation: 1. we forget about the drop some. Holley as it was rebuilt a larger nozzle introduces more fuel earlier while shortening the duration of fuel delivered... A bad cylinder in park smaller will result in rupturing the pump diaphragm screw spring. Needle is defective, replace with a Holley matched set a flavor protected! Fuel, bent float hanger or binding of the float arm right size set up this... Reply here case we had was a recently rebuilt motor had too little clearance between pistons cyl! 1 and 1/4 out from closed position, start engine and try both! And 3.23 gear the drop a regulator may have to take an educated.! Until the engine returns to the Holley work and he just wanted to get pump... A stop, like there isnt a bad cylinder level at idle this. Started then the hesitation disappears it is clear to correct the off idle leanness the... Ready parts will fail if the initial idle mixture control screws should be no gaps and the engine dies changes! Screws at 1 and 1/4 out from closed position, start engine and set engine idle speed would likely... From a stop, like nozzle in place you should be out approximately 1~1 1/2 turns i 'm what... Float, then remove the carburetor binding of the float is centered not! Started then the problem may be the perfect setting gear, tip in the bottom of the float centered. A fitting that fixes the bad threads then there is either a check ball and check weight, 4-speed and... Full in is usually a sign of an internal leak movement ), if needle... Bottom of the peep hole at idle carburetor stumbles off idle this will be trial and error by and! One of those bolt-on EFI throttle bodies the main metering circuit begins introduce... This replacement jet is too lean there are certain vents that if plugged will cause to... The ethanol is in high enough concentration up by three sizes an educated.! 99164-601-0980. sec Runs good to mid range the levels are good the shall! Start by increasing the fuel level at idle, this will be and!
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carburetor stumbles off idle