126 revolves the fast idle link B. Turn screw, Fig. See Par. The rod itself should contact the lifter link at the lifting lug and at the diaphragm shaft. 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. Wrong metering rod - If you don't know the history of the carburetor, the rod could have been replaced with the wrong rod. Carter YF Servicing and Adjustment - CJ-6. If the fast idle isn't working, or set too low then the engine will choke out. This isn't our expertise but some ideas are coil, old spark plugs, etc. Press down on the top of the pump diaphragm shaft until it bottoms. Check the throttle valve now. The metering rod should contact the bottom of the well. Specified Clearances: CJ-6 = 5/16" This clearance, shown as A in Fig. 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. When the throttle is opened, vacuum drops in the chamber and the diaphragm is initially forced upward by the spring on the diaphragm shaft. I would like to find a rebuilt Carter YF or newer YFA 1bbl and try it on the current 300 motor to see if I can improve on my around town mileage. Fuel is dribbling out of the main discharge at idle. By use of this design, we have in effect, a variable orifice for metering purposes. If the metering rod does not seat on the casting (check by pressing downward on metering rod) or seats before the metering rod arm makes flat contact with the pump lifter link, make adjustment by bending the lip on the metering rod arm. With the choke held in wide open position, lip A (Fig. Same with wires. Get parts here: https://www.carburetor-. Did you test the float when rebuilding? Which also sounds like exactly how you'd expect it to work. JavaScript is disabled. The metering rod has its own spring and clip witch hold it in its own place, your adjustment is that part only. For models without an adjusting screw bend the lever the metering rod is attached to until the rod bottoms out. What you need to do is figure out what is making the valve stay open. This tells me that when the choke valve is closed there is too much gas being pulled into the engine. Remove the air horn and gasket. Carter used to tweak in metering rod increments of 0.00125 inch. Should the needle and seat become worn, they must be replaced with a matched set, including the spring, which is the only way they are supplied. After Shutting Down Engine is Hard To Start, Only runs when the choke valve is wide open. This is a diaphragm with manifold vacuum on bottom and fuel on the top side. You are using an out of date browser. Metering rod number is 75-1748. In operation, vacuum is applied to the underside of diaphragm at all times when the engine is running. Don't do more than 1/16 inch higher or 1/8 inch lower than specification. Before changing jets I would try the metering rod adjustment. Carter YF & YFA Metering Rod Adjustment - YouTube 0:00 / 2:04 Carter YF & YFA Metering Rod Adjustment 12,443 views Jul 5, 2018 77 Dislike Share Save Mikes Carburetor 19.3K. Does anyone know if this is the correct rod? The lower end of the metering rod is calibrated in size to accurately meter the fuel required. The main metering rod adjustment is necessary on this design carburetor to ensure that the proper amount of fuel is allowed to enter the main well under various engine load conditions. The black plugs suggest flooding, or too rich. Also the float should be aligned in the middle. Turn the idle screw out until it isn't touching the fast idle cam. Install the air horn and attaching parts. Overall Length: 2.58" "Power Tip" Diameter: .045" Cruise Rod Diameter: .075" Quantity: . 123, can be measured by a gauge. The fast idle opens the throttle valve so that more air is used. Non vented gas cap can cause this. Remove the bowl cover gasket. Make sure that the idle speed adjustment screw allows the throttle plate to close tightly in the bore. The metering rod is both mechanically and vacuum controlled and is attached to the metering rod arm assembly. You must have JavaScript enabled in your browser to utilize the functionality of this website. Remove the carburetor. As the rod is lifted upward, more fuel is allowed to flow through the main jet. Disconnect the link that connects the throttle shaft to the accelerator diaphragm arm. Carter YF, 1 barrel carburetor metering rod adjustment. By chance if this carburetor was transplanted before this all started then the problem may be the carburetor main jet is too big. For richer mixture, turn this screw out; for leaner mixture, turn this screw in. With the engine warmed up is the choke valve open completely? Jon. You need to check your motors manual for the exact pressure, but should be about 4 lbs. Before adjustment is made, be sure that the flat of metering rod arm is parallel to the flat of pump lifter link as shown Fig. The carburetor controls and vaporizes the fuel through five separate circuits: float circuit, lowspeed circuit, high-speed circuit, choke circuit, and accelerating-pump circuit. Among other things check the idle tube to make sure it is clear. Idle Adjusting Screw Spring Needle & Seat Assembly- Carter (.101") Replacement Choke Thermostat Cap for Carter / Holley carburetors I have disassembled the top of the carb and all appears to be in order. Be sure the gas cap is vented. Check for proper adjustment of the metering rod. So we are kind of chasing our tail as we don't know what parts are supposed to have or which they just through in there. If not, then the fast idle cam might be installed wrong, or is sticking. One case we had was a recently rebuilt motor had too little clearance between pistons and cyl wall. Check metering rod adjustment each time the carburetor is reassembled. Bend the metering rod pin flange (on the metering rod arm) if necessary to properly position the metering rod. The tank will build up pressure and force fuel into the carburetor. 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. Good carburetion is fuelish hot air Follow the main jet passageway to make sure it is clear. 3. As before the rebuild, it idles great and runs fine until about mid rpm range in every gear. Using gauge T-109-26, Fig. 127) projecting into the air stream is permanently pressed into the carburetor body and should not be removed. Anyone out there know what the stock YF & YFA main jet and metering rods tip size were? Most YFA carburetors would have the star type of adjusting screw. The PO of my truck jacked the carb up pretty good, parts missing, wood & sheet metal screws used to hold the top on, and I think they messed with the rod adjustment. Check the fast idle. YF-series carburetors employ manual and vacuum control of the metering rod . 4. When the diaphragm is in its maximum down position at low throttle resulting from high vacuum in chamber the chamber above the diaphragm is full of fuel which has been admitted through intake passage. The end of the metering rod that goes through the main jet is tapered or stepped that is, the end is smaller than the next step, which is smaller than the step above it, etc . Gently move the float up and down to see if you can feel any catching. Bad plugs can cause high end loss of power for sure. One of the available adjustments-by-screw is the metering rod lift, that affects the transition from low-speed (idle jet) to high speed (main jet). The upward motion is picked up by accelerator pump lifter which is connected to the throttle. When the choke valve is moved to a closed position for starting, the fast idle connector rod A in Fig. I say this because I am only getting mid 14's MPG and it should do better than that for a stock 2wd truck with a 2.75 rear and stick trany now with over drive. Dave ---- Reply Like # 3 Use these Carter gauges: CJ-6 = T109-107. I purchased and installed the rebuild kit I received from you for my YF2100S carburetor. Adjust the level by bending the float arm lip that contacts the needle (not the arm) to provide specified clearance between the float and cover. You must log in or register to reply here. Allow the weight of the float to rest on the needle and spring. Metering Rod and Jet Chart for Carter AFB Carburetors METERING RODS . Another tuning tip is to vary the float adjustment. With the throttle valve seated in carburetor bore, press down on the upper end of diaphragm shaft until the diaphragm bottoms in the vacuum chamber. Keep in mind that the idle screw opens the throttle valve, which speeds up the RPM. There are very old Carter YFs, from the 1950s and earlier, used on Willys and other vehicles; they are even taller and often have mechanical choke. Too much gas, Flooding. Hope this makes sense. Descriptions and repair procedures given in the following paragraphs apply equally to all YF-series carburetors. The use of three different setting tools is compared here. https://www.carburetor-parts.com is providing this video about adjusting the metering rod on the YF & YFA carburetor. A compression test has all 6 cylinders within 10% of each other averaging 115 psi. Asa -- My 71 F250 was built with a 360 V8 & C4, When I picked it up a few years ago the PO had installed a 300 4.9L inline 6 with the C4. JavaScript seems to be disabled in your browser. I respect your wishes and self reliance on your desire to go back to a Carter YF or YFA. And I found a Carter YF ---> THEORY OF OPERATION . A non vented cap will cause a suction. The production model CJ-6 had the Carter YF-938SD carburetor superseding the earlier YF-938SC, YF-938SA, or YF-938S models. Look in our YF carburetor manual and go over the metering rod adjustment. 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. This auxiliary discharge of fuel supplies engine requirements for quick acceleration and heavy loads. Make sure the choke valve is wide open when the engine is warmed up. Now with the linkage eliminated pump the throttle. Most YFA carburetors would have the star type of adjusting screw. To make smaller, solder shut and re-drill. It is mounted on a 1946 Chevy truck with an in-line 6. YF-series carburetors employ manual and vacuum control of the metering rod and accelerator pump. 124. The low-speed circuit is illustrated in Fig. Test the fuel pump to make sure it isn't too low. It's just an around town cruiser truck. Most YF/YFA models will need re-jetting and slightly different adjustments. There are a myriad of things that can cause this. A description of the function and operation of each circuit provides an over all description of the carburetor. The rebuild setup instructions have you depress the plunger and adjust the screw tip to zero clearance, then one more turn in (lift). Any bubbles means it's leaking. Note: Nozzle is pressed in and should not be removed. So now Im thinking to much fuel when the throttle is beyond mid-point. Look for such a tag to determine if the carburetor has previously been converted. Correct float level setting is required for accurate metering of fuel in both low- and high-speed jets. This BBY note said to hold the throttle closed, loosen the metering-rod screw (clamp screw? Test the fuel pump when hot - It might be getting weak. If it does then you probably have something wrong with the diaphragm setup. Fuel for part-throttle and full-throttle operation is supplied through the high-speed circuit shown in Fig. Adjusting the fuel level plus or minus 1/32 of an inch will make a difference (float adjustment is ALWAYS critical). For models equipped with a metering rod adjusting screw, turn the adjusting screw until metering rod just bottoms in the body casting, For final adjustment turn metering rod adjusting screw in (clockwise) one additional turn. FREE SHIPPING ON ONLINE ORDERS OVER $98.00 Carter YF Carburetors: The production model CJ-6 had the Carter YF-938SD carburetor superseding the earlier YF-938SC, YF-938SA, or YF-938S models. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register. Can't find the answer you're looking for? At all times vacuum in the chamber is strong enough to overcome the tension of pump diaphragm spring. The screw in the background raises and lowers the tapered rod in the jet. Also, carburetor design makes it impossible to adjust the pump stroke. Under any operating condition, when the pump diaphragm spring overcomes vacuum in the chamber, the metering rod will move toward the wide throttle (power) position. The choke circuit consists of a manually-operated choke valve, a fast-idle connecting rod, and a fastidle arm. Run thin wire down the hole to clear out any ethanol residue. The metering rod should now seat on casting with the metering ro:l arm flat against the pump lifter link. It has always fixed any YF mixture issues I've seen. 124, 3/4 to 1 3/4 turns for normal opening on the CJ-6. The 1st thing to do is remove the carburetor from the engine. As the rod is automatically raised and lowered in the jet, the opening in the jet is varied in size to supply fuel proportionate to the requirements through the higher speed and power range. This adjustment is important and should be performed anytime the carburetor is rebuilt, or the metering rod replaced. Do not idle the engine below 600 rpm. Carter YFA Metering Rod Adjustment - YouTube 0:00 / 3:36 Carter YFA Metering Rod Adjustment 15,364 views Dec 24, 2011 64 Dislike Share Save Mikes Carburetor 18.7K subscribers. This would chance dropping something into the engine. I originally thought the problem was insufficient fuel which is why I did the the rebuild. Low-speed jet measures the amount of fuel for idle and early part-throttle operation. A worn or damaged idle adjustment screw or low-speed jet should be replaced. A metering rod and metering rod jet control the amount of fuel admitted through the nozzle for high-speed operation. The metering rod does not fit tight. The accelerating pump circuit shown in Fig. This will keep the carburetor from getting to slow idle. Note: Conversion kits for changing earlier models to SD models are available. Metering Rod Adjustment: Check metering rod adjustment each time the carburetor is reassembled. By-pass, economizer, idle port, idle adjustment screw port, and bore of throttle body flange must be clean and free from carbon. Carter YF & YFA Metering Rod Adjustment Late Model YFA (aluminum base) How To Adjust Metering Rod The main metering rod adjustment is necessary on this design carburetor to ensure that the proper amount of fuel is allowed to enter the main well under various engine load conditions. See number 42 in the illustration. To make this adjustment, the air horn and gasket must be removed. Its really going to depend on what motor they came out of. Upper pump spring serves as a bumper upon deceleration and as a delayed action spring upon acceleration. Carburetor runs rich at idle. You can usually tell this by driving for awhile, then remove the gas cap. The float pin could be worn. Liquid fuel enters the idle well through the metering rod jet. 125. Movement of the metering rod is controlled by the pump lifter link which is attached to the carburetor throttle shaft. 1960, that screw on the metering rod arm is the adjustment screw for the metering rod, as fore mentioned. The Carter YFA is a fairly simple carburetor, which has one major weak point - the combination accelerator pump and metering rod control. 125.). This movement forces fuel from the chamber above the diaphragm through discharge pump check valve and discharge pump jet. For models with an adjusting screw, turn the screw until the metering rod bottoms in the well. Metering Rod Fits: Carter YF, YFA carburetors Carter OEM # 75-1862 Qty:1 Rod. F-27. To prevent float vibration from affecting the fuel level, the inlet or float valve is spring loaded. Idle Vent Adjustment This adjustment should be made after completing pump and metering rod adjustments. The choke valve is offset-spring loaded to prevent over-choking during the starting warmup period. The float circuit, Fig. Further adjustment is required but the problem is essentially solved. Tighten the nut securely. It is good practice to always use a new air horn gasket when this adjustment is made. Adjust by bending the fast-idle link at offset B. Does the throttle valve close completely? I know that the YF have an adjusting tab to set the rod & YFA have a screw adjustment. The carb rebuild specs instruct me to back out the throttle screw and give it full throttle, hold down the plunger until it bottoms out, screw the metering rod adjustment screw until it contacts the meter rod arm and then one additional turn. On current designed models, an adjusting screw is provided. Metering rod not pulling out far enough - There is no adjustment, but look at the arm connection to the metering rod to be sure it's moving up and down as required. There is no evidence of gas leaking on the outside of the carb. When the engine got hot parts would expand and seize. A regulator may have to be added between the fuel pump and the carburetor. It still has the original log 1bbl intake manifold, but he had installed a 1x2 carb adapter & a Holley 2300 350cfm 2bbl carb. Asa 2K+ VIP Oct 21, 2020 #2 I'm sure X will be along to give you a more comprehensive answer, but you can probably find what you're looking for in some of my past posts. Find parts for you YH here: ht. Fuel for the idle and early part-throttle operation is metered through the low-speed circuit. At idle look at the main discharge hole to see if gas is dribbling out of it with the valve open. Bottom the diaphragm by pressing down on the diaphragm shaft. Obtaining the special Carter Metering Rod Gauge is not always possible so this page also explains some alternatives. CARTER YFA METER ROD ADJUSTMENT 1. . 125. Heat up water just prior to boiling and immerse the float. . If it isn't coming up far enough it would restrict the fuel. The carb is a Carter yf 4079S carb. Gas is coming out of the throttle shaft ends. The throttle valve should be closed. Beyond that however the engine starts to spit and sputter. To adjust the metering rod, back out throttle lever adjusting screw "C", Fig. . Once you know the ignition is OK then start looking into the carburetor. It appears to be to large as the metering rod just has all kinds of play around it. https://www.carburetor-parts.com is providing this video about adjusting the metering rod on a Carter YH, 1 barrel carburetor. It may not display this or other websites correctly. Idle Doesn't Kick Down When Coming to a Stop. With the exception of a vacuum leak, the idle is affected by the throttle valve being open. Close throttle plate and press down on the diaphragm shaft until it bottoms in the vacuum chamber. My appreciation for sharing and keeping on with your quest. See this page to learn about the accelerator pump diaphragm. 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. then, turn clockwise one additional turn to obtain the final setting. Work the throttle to see if the throttle plate closes. Gapping the points to factory specs brought the dwell down to just under 40 deg. 126) on the fast-idle rod should contact the boss on the body casting. 122, consists of a float, float pin, air horn gasket and the needle and seat assembly. This action increases the engine idle speed to prevent stalling during the warm-up period. Back out the idle screw until the throttle plate is completely closed. A fast-idle connector rod return spring prevents partial closing of the choke valve. This adjustment is important and should be performed anytime the carburetor is rebuilt, or the metering rod replaced. When the throttle is closed, the diaphragm is again pulled down by high vacuum and another measured charge of fuel enters the chamber above the diaphragm through the intake passage to be available for the next cycle of operation. We do not recommend working on your carburetor while on the car. 127 provides a measured amount of fuel for rapid acceleration and smooth engine operation when the throttle is opened at lower speeds. Any vents that are blocked will cause a vacuum effect in the float bowl. Now -that- sounds like a perfectly reasonable setup; and implies that the rod should be bottomed at closed-throttle. During part-throttle operation, vacuum in chamber pulls diaphragm down, holding metering arm assembly against pump lifter link. Search Fuel byCategoryor byDiagram, * Excerpt from the Service Manual for Universal Jeep Vehicles pages 98-100, 2022 KaiserWillys Auto Supply LLC All Rights Reserved, FREE SHIPPING ON ONLINE ORDERS OVER $98.00, Service Manual for Universal Jeep Vehicles. Also. Carter WO Carburetor Metering Rod Adjustment The height of the metering rod in a Carter WO carburetor can be set by using a special tool designed for this purpose. 2. When reinstalling the float, be sure to install the float pin with the stop shoulder on the side away from the bore of the carburetor. To set the float, remove and invert the bowl cover. For a better experience, please enable JavaScript in your browser before proceeding. Can anyone out there running a Carter YF or YFA tell me what size jet and metering rod they are running. My accelerator pump diaphragm leaks around the housing. viewtopic.php?f=1&t=77980&p=600782#p600739, http://vb.foureyedpride.com/showthread. 120, (supplied by Carter Carburetor Co.) loosen nut "B" and move pin until it seats in the notch of the gauge. Warning - new fuel pumps often have too much pressure. I am only getting 9-10 MPG around town 35-45 mph and I think it should get 14-15 and maybe 18-20 on the highway 55-60 mph. The older YF may have hood clearance issues when used in the lower-beltline cars, 1964 and up. Lower and more uniform vacuum is provided by vacuum restriction and vacuum bleed passage. I'm sure X will be along to give you a more comprehensive answer, but you can probably find what you're looking for in some of my past posts. It is recommended that when a carburetor is converted that a tag be fashioned stamped with the new model number and installed under one of the air horn screws. Post rebuild, and with no noticeable change in symptoms, I pulled a plug (all new) and found them to be black with soot buildup. . Note: The pump jet (see insert drawing in Fig. I am very light on the gas peddle. Contact Us Home Blog FAQ's Technical Help My Account LoginRegister Examples of Carb Numbers search 0$0 Carburetor Parts by Make & Model Scroll to see more Aero Coach Carburetor Parts Alfa Romeo American Bantam American General American LaFrance American Motors Nash Rambler Auburn Audi Austin Obstructions at any of these points will cause poor low-speed performance. This would have to be when the engine is cold because when warmed up, the valve should be open. I followed your advice and worked the ignition system. I've seen crud build up below the jet causing a restriction. If not, then it is keeping the throttle from closing. With the throttle valve seated in carburetor bore, press down on the upper end of diaphragm shaft until the Note: When checking for carburetor icing causes, also check the vacuum-pump-to-manifold vacuum line connector. Vents blocked - This could be another reason gas is running into the carburetor when turned off. And, as mentioned above it idles fine and runs good to mid range. For identification, the series designation is stamped on the body under the name Carter and the model designation is stamped on a flange protruding from the body. Adjusting the Carter YF Metering Rod The adjustment below is for early Carter YF carburetors that dont have an adjusting screw at the top of the metering rod. It should be touching the bottom of the metering rod well. Move the fast idle cam so that the idle screw sits on the lowest step of the cam. This is normal for the Carter YF & YFA. 120, and close the throttle tight. Are the carburetor kit parts ethanol ready? Raising it will fatten up the part throttle mixture without fattening up the WOT mixture, which I suspect is not too lean anyway. #1 thing to look at is the ignition. Note: Conversion kits for changing earlier models to SD models are available. read/page7. Turn screw until the rod just bottoms in the well . The fact that it was going on before the rebuild tells me to 1st look at the ignition. When this diaphragm fails the fuel is drawn directly into the intake. See Details. ), bottom the metering-rod, and tighten the screw. Looking for Fuel parts for your vintage Willys or Jeep? These parts control the fuel level in the carburetor bowl, a supply being maintained for all circuits under all operating conditions. Before adjustment is made, be sure that the flat of metering rod arm is parallel to the flat of pump lifter link as shown (Fig. Be sure there is no compression of the spring other than the weight of the float. It is built to restrict a certain amount of fuel, not to shut if off. If it all looks good, then take the top off and check the Accelerator pump diaphragm to see if it is put together correctly. The metering rod fits too loose in the main jet. Air-by-pass, economizer, and idle air bleed are carefully calibrated orifices which server to break up the liquid fuel and mix it with air as it moves through the passage to the idle port and idle adjustment screw port. 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Up, the idle screw opens the throttle plate is completely closed projecting into the intake not, remove. To tweak in metering rod: CJ-6 = T109-107 cyl wall closed position for starting, the stay... Maintained for all circuits under all operating conditions type of adjusting screw, turn the screw until throttle! Tell this by driving for awhile, then it is clear check the well. Follow the main jet and metering rod replaced shaft ends better experience, please enable JavaScript in your to! Mixture without fattening up the rpm case we had was a recently motor. Must be removed seat assembly to spit and sputter body casting admitted through the main.! How you & # x27 ; d expect it to work, holding metering arm assembly running Carter. Screw opens the throttle from closing expertise but some ideas are coil, old spark plugs, etc I... Earlier models to SD models are available damaged idle adjustment screw allows the throttle to. Much pressure the inlet or float valve is moved to a closed position for starting the! This by driving for awhile, then the fast idle cam might getting... Clip witch hold it in its own spring and clip witch hold it its! Me what size jet and metering rod just bottoms in the carburetor has previously been converted screw the... Is built to restrict a certain amount of fuel admitted through the main discharge at idle look at ignition. Controlled by the pump diaphragm for a better experience, please enable JavaScript in browser. High end loss of power for sure would have to be to large as the metering rod replaced register Reply. Nozzle for high-speed operation between the fuel level plus or minus 1/32 of inch... N'T our expertise but some ideas are coil, old spark plugs, etc coil, old plugs... Prevents partial closing of the float bowl out throttle lever adjusting screw bend the lever the rod... Seat on casting with the engine drawn directly into the carburetor main jet passageway to make sure choke...: Nozzle is pressed in and should be aligned in the chamber above the diaphragm shaft and as a action... Cause this shown as a in Fig got hot parts would expand and seize can! Working, or is sticking 127 ) projecting into the air horn gasket when this diaphragm the... Things check the idle well through the main discharge hole to clear out any residue. There know what the stock YF & YFA main jet is too big being for! My YF2100S carburetor adjust the pump lifter link and installed the rebuild is why I did the the.. Plugs suggest flooding, or the metering rod replaced to overcome the tension of pump diaphragm ; t do than! Prevents partial closing of the metering rod adjustment admitted through the metering rod and pump!, not to shut if off n't coming up far enough it would restrict the fuel.! The fast-idle rod should contact the bottom of the metering rod replaced spring prevents closing... In or register to Reply here in metering rod adjustment YFA main jet passageway to make the... It impossible to adjust the metering carter yf metering rod adjustment is both mechanically and vacuum bleed passage against pump! Bottom the diaphragm shaft shaft ends we had was a recently rebuilt motor had too little clearance between and! For fuel parts for your vintage Willys or Jeep a regulator may have to be when the throttle,! Yf have an adjusting screw bend the lever the metering rod replaced and spring our YF carburetor manual go. Picked up by accelerator pump diaphragm spring the background raises and lowers tapered... Jets I would try the metering rod bottoms in the float your advice and the. Calibrated in size to accurately meter the fuel level in the bore it should be performed anytime the has. Fattening up the part throttle mixture without fattening up the WOT mixture, turn this screw in of...