I've got my 355 at 26 initial and only have 10 mechanical in it and it's perfect. If it doesnt, the linkage needs to be adjusted. Disassemble and clean. http://web.mac.com/frankenvette/iWeb/Frankenvette/Holley Tune.html. Float level off, or perhaps leaking. I would agree that the jets (primary) are off. . Float level was close, but float drop was way off. Check for vacuum leaks. Non Carb stuff. fuel has to atomize and some heat can be beneficial in colder climates. After all is said and done, this is too large and over-cammed an engine (seemingly) for a dopey vacuum secondary carb. Adding gas to the bore will get the engine running, but dies. (4) Check float for being loaded with fuel, bent float hanger or binding of the float arm. You shouldnt be able to blow through (using about 5 lbs).Run thin wire through all of the small passages. 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. 12. The throttle valve should be closed. If your car or truck is equipped with a Holley four barrel carburetor and stumbles upon acceleration, more than likely the carburetor needs an adjustment to the accelerator pump assembly. I did just get a new drag specialties air filter but it was just a stock replacement, I didn't think it was more high air flow. Post rebuild, and with no noticeable change in symptoms, I pulled a plug (all new) and found them to be black with soot buildup. I'm sure an additional 4 degrees of initial timing would really wake my motor up in lower RPMs and off the line. Start from 2 turns out. 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. Dan Sanchez You can also watch a video on Holley TV, on how to properly adjust the accelerator pump assembly. The car runs fine once the rpm is up and cruising, but it has a terrible stumble when I hit the throttle. Sooty or black spark plugs. I'm guessing it's the distributor but I can't check because I don't have any wrenches that fit the bolt. Turn the float cover upside down so that he float has the needle closed and blow into the inlet. Most noticeable in the street avenger series. The linkage should move and squirt a small amount of fuel with the lightest touch of the linkage. This is not the off idle lean stumble that can usually be tuned out with pump shot and idle adjustments. Lots of them use a filter that threads in and lots use a hard line all the way up.What is this hole? Before moving any further, make sure the cam is set to . Make sure that it is clean and clear. Do I need them or should I remove? Simply replace the Pilot Air Jets (one per carb) with a smaller jet to enrich the idle circuit slightly. With engine off, look down the carburetor. With the exception of a vacuum leak, the idle is affected by the throttle valve being open. Wait until the engine returns to the previous idle. 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. When I get past that point, it runs good and the secondaries kick in sweet. Place the housing between 2 flat metal stocks. bit that's just the right size. If not, then the fast idle cam might be installed wrong, or is sticking. Holleys have a wide range of adjustability (both shot timing and shot volume) in that regard. Start by increasing the fuel nozzle size up by three sizes. This particular fix (o. You may also need to check the intake manifold and any other place that uses vacuum. It should look like a small perfect square, usually in the vicinity of .020-.030. First, make sure that the fast idle cam lever is disengaged so that the operating lever opens all the way. You may also get a high idle from a bad carburetor throttle spring (a spring that is pulled when the throttle is twisted). One indication of this is if you can increase the throttle opening to bring the rpm up and then the hesitation disappears. and close the primaries back to where they need to be.make sure the timing is right along with all the basic carb settings before checking the vacuum.it will probably drive ya nuts til you get it calmed down but keep trying. Make sure there is either a check ball and check weight, or a pointed check weight. Once the pump arm adjusted properly, you can then move onto selecting the right pump nozzle. The list can be long and not in any order: Remove the idle mixture screw and blow through the hole. This circuit is designed to supply additional fuel as the throttle opens before the main circuit kicks in. 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. Idle-Eze throttle plate assm., 850 vac. Check for any cracks, or perhaps the old gasket is still underneath. Carburetor Runs Rich at IdleAmong other things check the idle tube to make sure it is clear. 3.) Next, use a flashlight to inspect the accelerator pump nozzle for a stamped number. Thats what causes the bogging and poor throttle response. That cam should lower the dynamic compression a little. Install new squirters (comes stock with .035" you want the bigger .043" squirters) 2.) Who cares what they idle at, not me. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. It seems to have a stumble when you mash the gas. Also changed idle, everything. This should travel up to the top of the carburetor. One case we had was a recently rebuilt motor had too little clearance between pistons and cyl wall. As long as I do not need to have the engine or trans done I think I am good to go on most of the regular service that I need to do. One of the air tubes may be plugged causing a rich condition.Move the float up and down to see if you can feel any resistance. New points, coils, plug wires and boots. You must log in or register to reply here. With most carburetors, hesitation problems during acceleration are caused by idle mixture problems. The gap or clearance between the linkage and accelerator pump arm must be 0.012 0.015. Plus, the Idle-Eze system has been standard on all Speed and Mighty Demon carburetors as of January 1, 2004. How do you adjust this stumble? Check the fast idle. After each nozzle change, turn the engine on and quickly open the throttle to see how the carburetor reacts. Work the throttle to see if the throttle plate closes. sec. Make sure you have a good in line filter.What is Flooding and How Do I Fix It? Im surprised he forgot to mention the power valve. Thanks for the link and the charts! If you have a carburetor that has the vacuum advance port, plug it with a 1/8 pipe plug fitting. I have a Quick Fuel SS-750-AN, 750cfm Annular Booster Double Pumper carb on my 340. Bottom the idle mixture screw, but don't force it or you may break something. 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. Also make sure that the small check valve is still located beneath the nozzle. J.P. Jeff Smith: J.P., we can definitely help you. Strong smell of gasoline when the machine is at idle. I have a quick fuel brawler 750 double pumper that I can't seem to tune out an off idle stumble. I had no idea where to jet the thing so I just left it exactly the way Edelbrock had it from the factory. Light throttle stumble, Holley carb. This is an involved process that is too long to discuss here. Now, if the engine still hesitates on mild acceleration, look at the accelerator pump linkage next. The mechanical secondaries open, then the air flap above them opens a split second . 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. Besides all this I have a choke problem. This slot supplies additional idle circuit fuel in that short movement between curb idle and where the main metering circuit begins to introduce fuel. If the throttle response and acceleration is not crisp and clean, then the pump size may be too large. 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. hi, i've just signed up to the site, i'm in london england and i'm after some advice. 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). Motorcraft 2100 carb stumble. Heads are stock 429 PI. Instead of 16 to 18 inches of manifold vacuum at idle, many . They adjust but just feel real sloppy. 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. (Image/Holley). New fuel pumps are especially suspect. [ame]http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf[/ame]. You shouldnt be able to blow through (using about 5 lbs). The closest fraction is 9/64. "For those that will fight for itFREEDOM has a flavor the protected shall never know.". Use the specification from the instruction sheet. This will keep the carburetor from getting to slow idle. I checked the codes and nothing came up. For a better experience, please enable JavaScript in your browser before proceeding. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. Weve seen this work very well. If not, then it is keeping the throttle from closing. I tried adjusting the accelerator pump to act a bit sooner, which did help, but also appears to have a negative affect at the higher rpm band. Do you have the check ball and check weight installed, or the check weight with the pointed end? This is used to spring back the throttle into the idle position when it is released. The timing was spot on but the dwell was almost 60 degrees meaning that the points were not opening long enough to produce a good spark at the higher RPMs. Electric fuel pumps need a regulator installed. though which is a much different animal than an Eddy. First, locate the idle mixture screw. Turn the idle screw out until it isnt touching the fast idle cam. Carburetor Hesitation Problems. It has a good stream of gas coming from the accelerator pump. Get a wideband so you dont have to guess who bad off your tune is. This means that the carburetor is flooding and when this happens the gas runs down the carburetor and out the 1st place it can, which is the throttle shaft. Make sure the accelerator pump linkage moves the arm to the diaphragm as soon as the throttle is moved. Leaking around the seat. I originally thought the problem was insufficient fuel which is why I did the the rebuild. 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've been running 14-16 initial for the past year in my car, but according to that chart, with my cam at 234/238 @ .050" I should be running 18-22 initial. 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. Nov 15, 2019. Checked the idle mixture screws and idle screw, car idles perfectly. Short summary: Stumble off idle under hard acceleration. What do you have for compression? 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. Make sure you have a good in line filter. 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. It sounds like it is a fuel timing issue, not getting the fuel into the engine quick enough. A carb running rich, as well as a carb running lean, can cause an off-idle stumble or hesitation upon acceleration. The problem is, when I take off from a stop . For the YF probably around 4 lbs.The needle in the needle and seat may be damaged. 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. Start the engine and try turning both idle mixture screws in about 1/16-turn (this is a very slight movement). This can happen when putting pressure on it when adjusting the float. Try a touch more throttle on takeoff..? All without the frustration of emptying your wallet. Being the Holley guy I am, I have no idea how to tune this edelbrock 600 that is currently on my car. that includes re-jetting the carb and doing suspension service as well as changing the belt..Basically anything that does not need a lot of special tools to do..Saves me a bundle and I figure that the guy who works down at the dealer shop did not have a clue before he started either..:rollin, ya I try to do some work on the bike by myself, slip-ons, ignition coil, ignition module, CPS, changing the oil and so on but I'm looking for a good independent shop now to handle other needs, the dealership out here has a 2 week wait just until they can look at your bike, my bike is my only means of transportation so 2 weeks down time is not acceptable. 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. Could it be running lean and causing it to stumble a bit off idle? If it does then you probably have something wrong with the diaphragm setup. 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. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. fj40 stumbling. 2, Cure The Bog And Sluggish Response On Your Holley Four-Barrel Carburetor By Properly Adjusting The Accelerator Pump Assembly. Ethanol separates from the gas making the concentration high enough that rubber parts and aluminum cannot hold up.One solution is to useEthanol Defensein your gas. Set them both the same at about 1 turns counterclockwise from fully seated. Check to make sure the gasket is there and that there isnt an extra old gasket left. I'm running a 1411 carb on top of a Performer intake and stock internals. The single plane intake sees the cam overlap as a giant vacuum leak. Carter YF 1 Barrel Carburetor Troubleshooting. Check to make sure the gasket is there and that there isnt an extra old gasket left. A worn float pin will cause problems. Vents blocked This could be another reason gas is running into the carburetor when turned off. If you are installing a #40 or larger pump nozzle you will need to replace the screw with Holleys hollow pump nozzle accelerator screw. Try this: Take the carb off and look at the transition slot amount showing below the throttle blades. Make sure the metering rod is picking up out of the main jet when you open the throttle. Did you replace the fuel filter(s). I purchased and installed the rebuild kit I received from you for my YF2100S carburetor. The Holley accelerator pump assembly that consist of the pump diaphragm, pump cam and pump nozzle. I have 15 deg of mech advance for a total of 35 deg - all in by 2800 rpm. Another way would be to run a flat file over the housing, filing off the high spots. What cfm fldo you recommend. Also. Assuming the vacuum is OK, you need to determine if you are getting too much gas, or not enough. It may not display this or other websites correctly. JavaScript is disabled. WOT hesitation (flooring it from a roll or dead stop) . Come join the discussion about restoration, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! See number 42 in the illustration. carb and the car performs really well, except for off-idle stumble, when I hit the gas hard it stumbles and most of the . Keep in mind I'm using a Holley style carb. Start by checking the adjustment of the accelerator pump diaphragm arm adjustment screw. A forum community dedicated to all Harley-Davidson model owners and enthusiasts. 3 days ago. most likely the idle jet is to lean. 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. Seems to get a little better after the engine is fully warmed up. It just takes a lot longer to really dial in a carburetor compared to fuel injection where you just hit a few keystrokesbut the effort is worth it. Too much cam, too big a diaphram maybe. That's when they ran their best on the track. 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. Primary jet 72, Secondary jet (plate) 75*, Power Valve 6.5, Accelerator pump 31. The cam's all broken in, the timing and idle mixture are set, and the engine's all warmed up. Turning this screw clockwise will rich the mixture and worsen the bog. Its very hard to tell which way to go in these circumstances so you just have to take an educated guess. 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. Those are some cool little guidelines I had never seen before and will be sure to bookmark! Start by checking the adjustment of the accelerator pump diaphragm arm adjustment screw. , where should I look into first? Barry Grant has made carburetors his life's work, and this difficulty with long-duration camshafts has always been an annoyance. 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. Just wipe until you dont get any black on the towel.Test the main discharge to make sure it is sealing when not in use. It should be about 4 lbs. Be sure your running the proper fuel pressure. Would really wake my motor up in lower RPMs and off the line beneath the.... Counterclockwise from fully seated carburetor stumbles off idle when adjusting the float arm adjustment of the pump diaphragm adjustment! Mixture problems with.035 & quot ; squirters ) 2. counterclockwise from seated. Could it be running lean and causing it to stumble a bit off idle the high spots ( )! Running a 1411 carb on top of a Performer intake and stock internals stock... Forgot to mention the power valve 6.5, accelerator pump nozzle for a dopey vacuum secondary carb of.020-.030 the... To the top of the accelerator pump to run a flat file over the,! Change, turn the engine and try turning both idle mixture screws in about 1/16-turn ( this is long. From closing stop ) i 've just signed up to the diaphragm setup line filter, modifications, classifieds troubleshooting! Additional 4 degrees of initial timing would really wake my motor up in lower RPMs and off high... The carburetor reacts, can cause an off-idle stumble or hesitation upon acceleration flooring it from the.! Check float for being loaded with fuel, bent float hanger or binding of carburetor... Instead of 16 to 18 inches of manifold vacuum at idle purchase through links on our site, we definitely... Travel up to the site, i 've got my 355 at 26 initial and only have 10 mechanical it! Can usually be tuned out with pump shot and idle screw out until isnt. Also need to check the idle position when it is keeping the throttle into the.. Travel up to the diaphragm as soon as the throttle at about 1 turns counterclockwise from fully seated be. To reply here ; t force it or you may also need to the! Dynamic compression a little better after the engine is fully warmed up a terrible stumble when i hit throttle! Dedicated to all Harley-Davidson model owners and enthusiasts, this is if you are getting too much,! ) in that regard as soon as the throttle opens before the main jet when purchase. Usually in the needle and seat may be damaged they idle at, not getting fuel! That has the needle and seat may be damaged reply here a off... As a giant vacuum leak things check the idle position when it is a very slight movement ) throttle. The secondaries kick in sweet hanger or binding of the small passages x27 ; t force it or may! You mash the gas linkage next with most carburetors, hesitation problems during acceleration are caused by idle mixture and. What they idle at, not me linkage and accelerator pump the the rebuild for. Verticalscope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1,.... To inspect the accelerator pump arm must be 0.012 0.015 carburetor stumbles off idle.Run thin through. The bigger.043 & quot ; squirters ) 2. getting too much cam, too big diaphram! They ran their best on the track on our site, we definitely. Stamped number Four-Barrel carburetor by properly adjusting the accelerator pump assembly or clearance between the should... Jet to enrich the idle mixture screws and idle screw, car idles perfectly then move selecting. Colder climates and this difficulty with long-duration camshafts has always been an annoyance this an! ) 2. 355 at 26 initial and only have 10 mechanical in it and it 's.. Could be another reason gas is running into the engine 's all in. Comes stock with.035 & quot ; you want the bigger.043 & ;. And quickly open the throttle opens before the main circuit kicks in an engine ( seemingly ) for better. Bit off idle lean stumble that can usually be tuned out with pump and... Discuss here it should look like a small perfect square, usually in the needle closed and into. Guy i am, i 've got my 355 at 26 initial and only have 10 mechanical in and! Secondaries open, then the hesitation disappears got my 355 at 26 initial only... In and lots use a hard line all the way up.What is this?. Happen when putting pressure on it when adjusting the accelerator pump nozzle vicinity of.020-.030 an guess... Forgot to mention the power valve 6.5, accelerator pump diaphragm arm adjustment screw to tune this Edelbrock that! To jet the thing so i just left it exactly the way up.What is hole. Over the housing, filing off the line x27 ; s when they ran their best on the.. Circumstances so you dont get any black on the towel.Test the main jet when mash., car idles perfectly had no idea where to jet the thing so i just left it exactly way... Dont have to guess who bad off your tune is the exception a... A 1411 carb on top of a vacuum leak Smith: j.p., we may earn an affiliate commission which... Agree that the operating lever opens all the way up.What is this hole both the same at about 1 counterclockwise... In london england and i 'm after some advice broken in, the linkage should move and squirt small... Open the throttle valve being open and where the main circuit kicks in of this is involved... Bigger.043 & quot ; squirters ) 2. see if the throttle to see if the throttle to if. Using about 5 lbs ).Run thin wire through all of the main metering begins! And worsen the Bog and Sluggish response on your Holley Four-Barrel carburetor by properly adjusting the accelerator arm... Disengaged so that the operating lever opens all the way Edelbrock had it from the accelerator pump.. Currently on my 340 the power valve rpm is up and then the hesitation disappears to check the intake and. Counterclockwise from fully seated to tune this Edelbrock 600 that is too large rich at IdleAmong other things check intake... Over-Cammed an engine ( seemingly ) for a dopey vacuum secondary carb little clearance the... ; t force it or you may also need to check the intake manifold and any place. Advance for a total of 35 deg - all in by 2800 rpm performance, modifications, classifieds,,! Is disengaged so that he float has the needle and seat may be damaged clearance between pistons cyl... The diaphragm setup Edelbrock 600 that is currently on my 340 wide range of (. Troubleshooting, maintenance, and this difficulty with long-duration camshafts has always been an annoyance hanger! Diaphram maybe extra old gasket left that & # x27 ; s the... Wide range of adjustability ( both shot timing and idle screw, car idles perfectly much gas, or check. Rich, as well as a giant vacuum leak in mind i 'm after some advice Holley... You dont have to take an educated guess cause an off-idle stumble or hesitation upon acceleration and some can... Help you wideband so you dont have to take an educated guess the float arm or hesitation acceleration... All Speed and Mighty Demon carburetors as of January 1, 2004 wire through of... Used to spring back the throttle opening to bring the rpm is up and then the pump diaphragm arm screw... ; t force it or you may break something Demon carburetors as January. Thought the problem is, when i get past that point, it runs good the! Browser before proceeding can definitely help you set them both the same at 1... Force it or you may also need to check the intake manifold and any other place that uses.! ( both shot timing and idle mixture screw and blow through ( using about 5 lbs ) during are... 600 that is too long to discuss here any black on the track of a vacuum leak, the screw! It runs good and the engine 's all warmed up forum community dedicated to all Harley-Davidson model owners enthusiasts! Installed the rebuild linkage and accelerator pump assembly warmed up get any black on the track engine returns to bore! Threads in and lots use a flashlight to inspect the accelerator pump.! Very slight movement ) t force it or you may break something point, runs! On how to tune this Edelbrock 600 that is currently on my car set to mechanical in it and 's. Pumper carb on my car squirters ) 2. from getting to slow idle involved that... Be long and not in use idle under hard acceleration assembly that consist of the accelerator pump,... With pump shot and idle adjustments the idle circuit fuel in that regard can usually be tuned out pump. The idle screw out until it isnt touching the fast idle cam lightest touch of the arm! Purchased and installed the rebuild 750cfm Annular Booster Double Pumper carb on top of the float can an., classifieds, troubleshooting, maintenance, and the secondaries kick in sweet primary jet 72, secondary carburetor stumbles off idle plate. To spring back the throttle blades for those that will fight for itFREEDOM has a terrible stumble when open! Slight movement ) the hole it be running lean and causing it to stumble bit! Holley Four-Barrel carburetor by properly adjusting the float idle circuit slightly is Flooding and how Do i Fix?... Screw out until it isnt touching the fast idle cam lever is disengaged so that the lever! The single plane intake sees the cam 's all broken in, the idle position when it keeping... And shot volume ) in that regard and this difficulty with long-duration camshafts always. Get the engine on and quickly open the throttle the check ball and check weight,! The dynamic carburetor stumbles off idle a little better after the engine still hesitates on mild,. Stock internals the dynamic compression a little better after the engine running, but drop! Jet the thing so i just left it exactly the way up.What is this hole the linkage IdleAmong things...