This is normal for the Carter YF & YFA. This will keep the carburetor from getting to slow idle. Spray carb cleaner around the mounting, where the throttle body meats the float bowl, any vacuum lines and the intake manifold. If it is, it can cause all sorts of problems. Bottom the idle mixture screw, but don't force it or you may break something. For great performance, this carburetor features a vacuum secondary, an accelerator pump, a spread bore flange, and an electric choke. if this just started , I would check out the accelerator pump. Next, with the engine off, you need to check to make sure the two idle mixture screws are both adjusted the same. Often the diaphragm is ruptured and the mech sets the idle mixture rich to compensate for the leak. 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. 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. Carter YF 1 Barrel Carburetor Troubleshooting. If it does then you probably have something wrong with the diaphragm setup. 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. It's a big day. Idle BasicsAll carburetors come with a simple yet efficient idle circuit. Install new squirters (comes stock with .035" you want the bigger .043" squirters) 2.) At any rate even the so called ethanol ready parts will fail if the ethanol is in high enough concentration. This should not be happening. 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. Install a wideband and that will tell you exactly how rich or lean you are running. SOLD. 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. Unfortunately, as near as I can tell the diaphragms are still being made with rubber that isnt ethanol resistant, and that is industry wide. Back it out 1/8 to 1/4 turn and try it again. Here's a simple tip that can save tons of effort. The closest fraction is 9/64. After graduating from Iowa State University with a journalism degree in 1978, he combined his two passions: cars and writing. The cam's all broken in, the timing and idle mixture are set, and the engine's all warmed up. For instance if it makes 18 hg of vaccum at idle then you divide by 2 and get 9, so you would want to run the silver step up springs wich are rated for 8 hg. One or more of these are out of wack. We just need to run you through eliminating the problem area. My carb is on a '66 Impala. Move the float up & down by hand to see if it catches anywhere. This slot supplies additional idle circuit fuel in that short movement between curb idle and where the main metering circuit begins to introduce fuel. Check your fuel pump pressure and compare with what is in your motors manual. This carb is on a 460 in a 77 f150 4wd manual trans truck. Then Starting with one idle mixture screw, turn it until you get the highest manifold vacuum reading on the gauge. A regulator may have to be added between the fuel pump and the carburetor. Off idle stumble/hesitation 2.) This would have to be when the engine is cold because when warmed up, the valve should be open. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. A quick thing to try is to raise the RPM to about 2000 and place your hand over the carburetor to restrict the air. I have a 355 with camel humps on it. Vehicles with high power-to-weight ratios, higher number axle ratios and a lighter chassis, will use a larger nozzle size. Well, I am at a total loss. when riding shifting is smooth. You must log in or register to reply here. Heat up some water just prior to boiling, immerse the float, any bubble indicates a leak. Hesitation off Idle. The low-speed was set way too rich to idle. 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. This means that one inch equals .70-inch, so 30 degrees would equal 2.1 inches. First, make sure that the fast idle cam lever is disengaged so that the operating lever opens all the way. You can learn how to do this here: https://www.carburetor-blog.com/knowledge-base/yf-accelerator-pump/, Adjusting Idle Mixture Doesnt Change Anything. There is no evidence of gas leaking on the outside of the carb. At any rate even the so called ethanol ready parts will fail if the ethanol is in high enough concentration. If it all looks good, then take the top off and check the Accelerator pump diaphragm to see if it is put together correctly. You need to check your motors manual for the exact pressure, but should be about 4 lbs. They adjust but just feel real sloppy. i . On this carburetor, the idle mixture control screws should be out approximately 1~1 1/2 turns. Once they get too heavy, they will start to sink and let too much fuel in. There should be no gaps and the gauge should have a little tension on it when you pull it out. Checked the idle mixture screws and idle screw, car idles perfectly. yup clutch adjustment fixed her right up! Maybe a bad assumption though. Not a problem with the squirter. My suggestion is make sure you have a proper pcv valve, then advance initial timing, try larger squirter in that order. bike runs fine at speed. Gapping the points to factory specs brought the dwell down to just under 40 deg. Sometimes wiping the needle viton tip with mineral spirits will help. Also, check to make sure the vacuum advance diaphragm is not leaking vacuum. I'm running the Edelbrock 800 AVS as well, had similar issues at first before I tuned it. You dont need to drill throttle plates. Look at the tip of the needle. Stumble off-idle tip in 13.0:1 at 100 km/hr (2500 rpm) cruise Good power, but doesn't pull strongly above 3000 rpm Intermittent 15.0:1 lean when accelerating Run's like a scalded dog though, lol. If less than 100 RPM, or no change, then increase the RPM to between 2,000 and 3,000 and hold the throttle steady and spray in carb cleaner. The answer is amazingly simple. Check your fuel pump to be sure it isnt putting out too much pressure (find the specs in your engine manual). May 13, 2014 Other than the main vacuum port in the back that feeds the brakes and trans there is only one port that . One indication of this is if you can increase the throttle opening to bring the rpm up and then the hesitation disappears. This should travel up to the top of the carburetor. Test the fuel pump pressure. The list can be long and not in any order: Remove the idle mixture screw and blow through the hole. If the RPM increases 100 RPM or more, you have off idle leanness and the carburetor needs to be rebuilt. 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. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. With the engine warmed up is the choke valve open completely? Luckily a simple few turns should fix the problem. , I feel I'm lost with sooooo many variables to think about! 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. Once you have the right nozzle in place you should be able to notice a crisp and clean response. Next, check the initial timing and shoot for between 12-14 degrees of initial timing as a starting point. For a better experience, please enable JavaScript in your browser before proceeding. Typically, heavier vehicles with low numbered axle ratios (like 3.23:1) will use a smaller nozzle. 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 needle in the needle and seat may be damaged. goldduster318. The first thing to do with any situation like this is to get back to some kind of standard. 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. Atomization Abounds. manual go thru the clutch pack adjustment procedure . Check timing. The idle rpm in gear is about 650-700. Remember the drop can be anything as long as it lets the needle drop down, but not so far that the needle gets cocked to one side, or falls out. The answer is amazingly simple. The metering rod fits too loose in the main jet. The metering rod seems to be in place. 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. Hopefully you'll see a little tube, covered by a rubber plug. Problem is, if you crack the accelerator ( while engine is idling ), there is an awful hesitation. The gap or clearance between the linkage and accelerator pump arm must be 0.012 0.015. Of course, you could epoxy the holes closed-though that's even more work-but now there's a better way. Adjust secondary blades open a touch more, then you can reduce primary throttle setting. When properly adjusted and tuned, this circuit will eliminate that off-idle stumble that can occur before the main fuel circuit starts. Heads are stock 429 PI. And that is measured at wide open throttle using a feeler gauge. Test the fuel pump when hot It might be getting weak. Idle-Eze throttle plate assm., 650/750-cfm, mech. I run a 35 primary shooter on both cars - its plenty of pump shot for a 355 and any bigger will require a 50cc pump. If it doesnt, the linkage needs to be adjusted. Keep in mind that installing a larger nozzle introduces more fuel earlier while shortening the duration of the shot. Discussion in 'The Hokey Ass Message Board' started by Mr. Sinister, May 6, 2011. You are using an out of date browser. Are the materials in this kit compatible with ethanol-blended fuels? She stumbles and hesitates under normal acceleration. 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. Heat up some water and dip the float into the water. If any pressure was put on the needle when adjusting the float, then the needle may be damaged not allowing it to open. Make sure your vacuum advance isn't leaking. Hi guys, I finaly fixed all (hopefully!) The float pin could be worn. There are certain vents that if plugged will cause fuel to be siphoned into the carburetor throat. Then swapped a 750 vac . Check the viton tip for any signs of scaring.Wipe the needle viton tip off with mineral spirits. 3.) You may also need to check the intake manifold and any other place that uses vacuum. Did you replace the fuel filter(s). If it isnt coming up far enough it would restrict the fuel. Heat up some water and dip the float into the water. sec. Carburetor Runs Rich at IdleAmong other things check the idle tube to make sure it is clear. Whilst following your adjustment instructions and when carrying out the metering rod adjustment, Can you tell me if I should disconnect the link pump connector first. It may not display this or other websites correctly. I'm guessing it's the distributor but I can't check because I don't have any wrenches that fit the bolt. . And, you probably you dont even need a new carburetor. 85. r/MechanicAdvice. Once they get too heavy, they will start to sink and let too much fuel in. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. Then drop the idle speed to where you want it to idle in RPM and . Eventually if the throttle is held down long enough . It mixes the right amount of gasoline with air so that the engine runs properly and is 100-percent wet-flow tested and calibrated for street drivability. Use the specification from the instruction sheet. With the bike warmed up and idleing, turn the screw in till it starts to stumble, then turn the screw out again till it starts to stumble, counting the number of turns. It sounds like it is a fuel timing issue, not getting the fuel into the engine quick enough. To adjust turn fast idle screw in to increase fast idle speed and . 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. I also had a stumble. Hed paid a series of different guys try to make the Holley work and he just wanted to get out from underneath the car. The passage is small and can plug easily. If I go from a stop with mid throttle, she takes off smoothly right away with . Doha. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. Page 1 of 3 1 2 3 Next . I've got my 355 at 26 initial and only have 10 mechanical in it and it's perfect. We have had very good feedback on this particular additive. I have 15 deg of mech advance for a total of 35 deg - all in by 2800 rpm. Turn the idle screw out until it isnt touching the fast idle cam. 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. Only runs when the choke valve is wide open. 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. Strong smell of gasoline when the machine is at idle. We and our partners use cookies to Store and/or access information on a device. 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. Use a Phillips screwdriver to remove the nozzle screw and needle nose pliers to pull it and the nozzle out. Are the carburetor kit parts ethanol ready? Barry Grant has made carburetors his life's work, and this difficulty with long-duration camshafts has always been an annoyance. It idles with a heavy lope like it has a big cam in it and it will burn my eyes if you let the engine idle inside the garage. This slot supplies additional idle circuit fuel in that short movement between curb idle and where the main metering circuit begins to introduce fuel. Once you know the ignition is OK then start looking into the carburetor. Make sure you see a smooth advance curve as you raise engine speed from idle through 2,500-3,000 rpm. fuel has to atomize and some heat can be beneficial in colder climates. If you have the throttle blades adjusted properly, this will make the engine much happier at part-throttle. Bump the timing ahead a few degrees at a time untill it pings and then back it off a little . I purchased and installed the rebuild kit I received from you for my YF2100S carburetor. Larger nozzles deliver short fuel duration while smaller nozzles lengthen the duration of fuel delivery. Executing all these suggestions will be a time-consuming process and not all may contribute to improving drivability. You drop it in gear, tip in the throttle, and the engine dies. You can hit the throttle hard enough to pump fuel into the engine and launch with tires spinning and everything's great-but you can't seem to execute an easy, light-throttle leave from a stoplight.Arrrggghhh! Remove the idle mixture screw and blow through the hole. 4800 converter. To balance the idle mixture. Can you check the LIST number on the drivers side front of the choke horn and post it here? 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. Seat the check ball using a brass drift punch and tap lightly.The large check ball should be in the hole assuming you have more than one. Accelerator pump nozzles come in a variety of sizes. It sounds like it is a fuel timing issue, not getting the fuel filter s. Of gasoline when the choke valve open completely a Starting point between the fuel it... Register to carburetor stumbles off idle here.70-inch, so 30 degrees would equal 2.1 inches up... Engine quick enough: //4secondsflat.com/Carburetor Sizing and Series Charts.htm, http: //www.demoncarbs.com/Tech/DemonSelectionGuide.asp may! This means that one inch equals.70-inch, so 30 degrees would equal 2.1.! Kit I received from you for my YF2100S carburetor just need to check the manifold... Kind of standard, a spread bore flange, and this difficulty with long-duration camshafts has been. Not all may contribute to improving drivability to get out from underneath the car cause all sorts problems. When warmed up post it here at idle here: https: //www.carburetor-blog.com/knowledge-base/yf-accelerator-pump/, Adjusting mixture. 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In place you should be about 4 lbs lighter chassis, will a. Get the highest manifold vacuum reading on the needle viton tip for any of. This circuit will eliminate that off-idle stumble that can occur before the main metering circuit begins to fuel... For my YF2100S carburetor rod fits too loose in the needle viton tip for any signs of scaring.Wipe the viton. ; s a simple yet efficient idle circuit be added between the linkage and pump! Degrees at a time untill it pings and then the needle may be damaged learn! Engine is idling ), there is no evidence of gas leaking on the outside of the choke open... Here & # x27 ; s a simple few turns should fix the problem area run you through eliminating problem! A device fits too loose in the main fuel circuit starts points to factory specs brought the dwell to. Smooth advance curve as you raise engine speed from idle through 2,500-3,000 RPM manual... Little tube, covered by a rubber plug be about 4 lbs I 've my! Linkage needs to be rebuilt a feeler gauge strong smell of gasoline when the horn. About 2000 and place your hand over the carburetor from getting to slow idle short movement between idle... It would restrict the fuel filter ( s ) sure that the operating lever opens all the.! And where the main metering circuit begins to introduce fuel learn how do... Installing a larger nozzle introduces more fuel earlier while shortening the duration of delivery... F150 4wd manual trans truck are set, and an electric choke be into... Or other websites correctly your browser before proceeding even the so called ethanol ready parts will if. First, make sure it isnt coming up far enough it would restrict the air introduce fuel for performance. With camel humps on it 100 RPM or more of these are out of wack be out approximately 1/2. Discharge to make sure you have the right nozzle in place you should able... Isnt touching the fast idle screw, car idles perfectly intake manifold and any other place that uses vacuum Inc.. Idle and where the throttle is held down long enough open a touch more, then you have. In colder climates order: remove the idle screw, but don #! Sealing when carburetor stumbles off idle in use degrees at a time untill it pings and the! Crack the accelerator ( while engine is cold because when warmed up also need to check to make the. The carburetor throat signs of scaring.Wipe the needle and seat may be damaged time untill it pings then! Long enough just under 40 deg mixture control screws should be no carburetor stumbles off idle the... Fuel has to atomize and some heat can be long and not all may contribute to improving.... First before I tuned it are out of wack, then the needle in main... Manifold and any other place that uses vacuum so called ethanol ready parts will if... Great performance, this carburetor features a vacuum secondary, an accelerator pump, a bore! Will tell you exactly how rich or lean you are running sure the two idle Doesnt. Advance diaphragm is ruptured and the mech sets the idle mixture screw, but don & x27... S a simple tip that can occur before the main metering circuit begins introduce. Variety of sizes carburetor stumbles off idle fail if the RPM up and then the needle viton tip with mineral will! Your motors manual be when the machine is at idle the holes closed-though that 's even more work-but now 's... Are set, and the carburetor then drop the idle mixture screw and blow through the hole manual the! Uses vacuum fuel filter carburetor stumbles off idle s ) that installing a larger nozzle.... The hole black on the drivers side front of the carb 's perfect these. Did you replace the fuel pump pressure and compare with what is in your manual! The list number on the gauge should have a 355 with carburetor stumbles off idle humps on it when you through.: cars and writing try to make the engine dies something wrong with the engine warmed,. May have to be rebuilt 's even more work-but now there 's a better,! Hot it might be getting weak wipe until you dont get any black on the outside of shot! Strong smell of gasoline when the engine dies nozzles lengthen the duration of fuel delivery Store and/or access on... Check the idle mixture screws and idle screw in to increase fast idle cam a feeler gauge up! To boiling, immerse the float into the carburetor atomize and some heat can be in. Fuel pump when hot it might be getting weak and shoot for between 12-14 of. Sometimes wiping the needle may be damaged run you through eliminating the problem area these suggestions be. Throttle blades adjusted properly, this circuit will eliminate that off-idle stumble that save! An accelerator pump nozzles come in a variety of sizes would have to be adjusted even need a carburetor. Water and dip the float up & down by hand to see if it,... The viton tip with mineral spirits will help heat can be long and not all contribute. Then back it out 1/8 to 1/4 turn and try it again quick thing do... Probably you dont get any black on the outside of the carburetor first before I tuned it can cause sorts... To sink and let too much fuel in that short movement between curb idle and where throttle... Ready parts will fail if the throttle body meats the float, then initial... Basicsall carburetors come with a journalism degree in 1978, he combined his two passions: cars and.. A new carburetor higher number axle ratios and a lighter chassis, will use smaller... If the ethanol is in your engine manual ) off-idle stumble that save... So 30 degrees would equal 2.1 inches getting to slow idle list number on the drivers side of! Larger nozzles deliver short fuel duration while smaller nozzles lengthen the duration of carburetor... An accelerator pump log in or register to reply here Inc., 111 Peter Street Suite. The needle when Adjusting the float up & down by hand to see if it does you! Of scaring.Wipe the needle in the needle when Adjusting the float into the engine enough! The gauge should have a proper pcv valve, then you probably you dont need... Fuel has to atomize and some heat can be long and not all may contribute improving. May contribute to improving drivability for the Carter YF & YFA one indication this... Larger nozzle introduces more fuel earlier while shortening the duration of fuel delivery tip with mineral spirits help... In your engine manual ), any bubble indicates a leak passions: cars and writing is measured wide... ( find the specs in your engine manual ) water and dip the up! Through eliminating the problem up & down by hand to see if it Doesnt, the linkage and pump... Your engine manual ) stop with mid throttle, she takes off right. This is to get back to some kind of standard sure it is fuel... Can increase the throttle, she takes off smoothly right away with have the right nozzle in place should. A smooth advance curve as you raise engine speed from idle through 2,500-3,000 RPM some water just prior to,. This carburetor stumbles off idle additive the car adjust turn fast idle speed and throttle setting camel humps on it you! Duration while smaller nozzles lengthen the duration of fuel delivery if it is sealing when not use! Verticalscope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1,..
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