Carter YF YFA Carburetor

Carter YF Problems and Solutions

How to find the Carter YF, YFA carburetor number?
Which means finding the correct kit.


Fuel Inlet System

As shown, fuel enters between the needle valve seat and needle valve to fill the fuel bowl. The fuel flow is float controlled. Accordingly, the fuel level raises the float arm against the needle valve to the point where it seals against the valve seat and shuts off the fuel. As fuel is used by the engine, the level drops slightly, and additional fuel is admitted through the needle valve and valve seat. In actual operation, a fairly steady float position and fuel flow condition exists. The inlet system parts and the carburetor are of all-metal construction, except
the needle valve, which has a plastic tip. A spring separates the inlet needle valve from the operating pin to cushion the needle valve and float operation. An
internal vent connects the fuel bowl to the air horn. Some external venting is effected through the pump lifter link slot in the main body casting.

Idle System

Fuel enters the idle well through the metering rod jet shown. The low-speed jet measures the amount of fuel for idle and early part-throttle operation. The upper idle air bleed, fixed idle restriction, and lower idle air bleed are carefully calibrated and serve to break up the liquid fuel. The fuel is then mixed with air as it moves through a passage to the idle port and idle adjustment screw port. Turning the idle adjustment screw inward reduces the quantity of air-fuel mixture supplied by the idle system. The idle port is slot-shaped. As the throttle valve is opened more of the Idle port is uncovered allowing a greater quantity of the air-fuel mixture to enter the carburetor bore.

YF Idle System

Carter YF Carburetor CatalogCarter YF Carburetor Manual

YF Carburetor Identification

When no carburetor number is present, you may be able to identify your carburetor by using the casting number.


Casting Number Carburetor Number Application
630 768s, 938s, 951s Willys
630 787s, 964s, 2008s Chevrolet
630 832s Willys
648 738s, 937s Willys
648 814s, 820s, 833s Henry J
650 735s, 736s, 740s, 741s, 939s International
728 756s, 965s Chevrolet
776 757s, 824s, 876s, 877s, 892s, 2014s, 2098s, 2137s, 2163s Nash
788 788s, 966s Chevrolet
791 789s, 967s Chevrolet
866 879s International
875 924s, 2071s Willys
875 2094s Kaiser Darrin
1052 2046s Chevrolet
1105 2079s Reo
1121 2101s Chevrolet
1127 2100s Chevrolet

Check Balls

Check balls are often placed in the wrong hole, so don’t assume you will find the correct size in the particular hole.

The bigger check ball goes in the main discharge.

Once the check balls are in place you will need to test them to make sure they seal correctly. Use a test fluid, like carburetor cleaner (NOT WD-40), and a small punch to gently hold down the ball on it’s seat and depress the pump in it’s well by hand. If you get a hydraulic lock then you are good to go. On holes other than the accelerator pump simply watch that the fluid doesn’t leak out.

When the check ball isn’t sealing, then you will need to re-size the hole by tapping on the check ball a couple of times. DO NOT use the new check ball for this. It could become mall formed. Use the old check ball if it isn’t corroded or beat up

YF Metering Rod Adjustment

YF Metering Rod Adjustment

The adjustment below is for early Carter YF carburetors that don’t have an adjusting screw at the top of the metering rod. Most YFA carburetors would have the star type of adjusting screw.

This adjustment is important and should be performed anytime the carburetor is rebuilt, or the metering rod replaced. With the throttle valve seated (this means the idle screw is not holding the valve open) in the bore of carburetor, press down on upper end of diaphragm shaft (C) until diaphragm bottoms in vacuum chamber. On carburetors which have the projection (D) on the pump lifter link, metering rod should contact the bottom of the metering rod well (E), and metering rod arm (F) should contact lifter link (G) between springs and at supporting lug (D). Adjust by bending lip (H) up or down. In the illustration there is a tool that can be used to hold down the diaphragm, but chances are you won’t have one of those and it isn’t that big of a deal to hold it down.

On models that do not have the projection (D) on pump lifter link, the metering rod should bottom in the metering rod well (E) and flat of metering rod arm (F) should make parallel contact with flat of pump lifter link (G). Adjust by bending the lip (H) up or down.

Needle & Seat

Some of our kits have two sets of needle & seats. One will be spring loaded and the other will not be. Try to use the spring loaded whenever possible, especially on off-road vehicles. The spring type of needle & seat keeps the float from bouncing on a rough road, which will allow too much fuel to enter the float bowl.

.Find Carter YF main jet sizes here.


68 thoughts on “Carter YF YFA Carburetor

  1. Howdy, I tried to save a buck by buying a “RALLY” rebuilt carb for my 1972 inline 6 – I believe to be a 300ci but maybe a 240. I removed a Carter YF (not YFA) which had and electric choke assembly and choke adjustment. The “RALLY” replacement carb (which came identical) worked fine after the install for about 10 minutes. After warmup, it began dribbling gas beneath the float bowl below the metering valve. At first, I thought is was the gaskets. I changed them out / singled and doubled them / but still, after about 10 minutes of warming up – the dribble came back. I returned the carb for another and guess what? Yep- the same identical thing happened. What am I missing / doing wrong? Is the Rally carb just a piece of junk? Thanks.

  2. Mike,
    I have a YF 788 on a ’55 Bel Air with a 235. I have gone through the carb and cleaned everything. Disassembled it, them dipped it, rebuilt it with a kit. Set float at 15/32″ top and 1 1/4″ down. Replaced all gaskets, rubber etc. I am getting getting fuel through the venturi at idle. Any thoughts on this issue? Float/needle is seating, fuel pressure is around 5 so I don’t think it is pushing past. No leaking as soon as I shut it off. Metering rod is deep in the jet. Any thoughts where to look next?
    Thanks, I am totally stumped now.

  3. Mike,
    I have a YF 1-788 on a ’55 Bel Air with a 235. I have gone through the carb and cleaned everything. Disassembled it, them dipped it, rebuilt it with a kit. Set float at 15/32″ top and 1 1/4″ down. Replaced all gaskets, rubber etc. I am getting getting fuel through the venturi at idle. Any thoughts on this issue? Float/needle is seating, fuel pressure is around 5 so I don’t think it is pushing past. No leaking as soon as I shut it off. Metering rod is deep in the jet. Any thoughts where to look next?
    Thanks, I am totally stumped now.

  4. Having an issue with finding a kit for my YF. It’s on my Willys jeep and it’s definitely not stock. I know it ran good 20 years ago! The carb is stamped YF 6350S. I haven’t been able to match this number with any kits available. Help!!! I would

  5. Hi,
    We are currently rebuilding a Carter YFA 4776 S Model and found that someone has previously placed a couple of small screws in the main body near the bottom of the fuel bowl, these screws are obviously not factory and appear to be someones attempt at stopping a fuel leak.
    I have attached a picture with what appears to be the same model YFA as mine and circled the 2 holes where we found the screws. In the carburetor pictured it appears the holes are filled with some type of material, epoxy maybe?

    Would you please tell me what I should do with the holes.

    Thank you!


  6. I started the teardown to rebuild the carb off a 1978 F150 300.The truck had a hesitation when accelerating and gas could be found the bottom of the fuel bowl. The truck would occasionally after fire and diesel when shut off. I found the inlet check valve (ball) on the accelerator pump housing with a hole on the top and bottom of it open. It appears that there should have been a welch plug installed in the top hole (.25″), otherwise it would not “check”. I also found the metering rod spring off the metering rod. Pump diaphragm looked good. I did not find the gasket that slips over the pump lifter link . Do you think this could have been the problems? Carb stamped number is 7051S, tag was partially torn and reads D5TE , think it was AGB afer that. I am waiting for the K4073 kit to re-assemble. Saw a video mentioning an extra gasket below the accelerator pump diaphragm to stop leaks (in Hygrade kit 518C). Have you come across this before?

    • Use a flat file on the bottom of the housing to make sure it is flat. The extra gasket is not available that I know of. The number 7051S is enough of a carb number. Carter made these for Motorcraft which is why they can have two different numbers. The pump lifter gasket comes in the kit. Without it you may have spill over which could cause the problems you describe.
      Can I get photos of the inlet check valve area?


        • Mike, Did you get a chance to look at the pictures? I found 2 gaskets between the aluminum spacer with the brake booster vacuum take-off and the intake manifold. Does the thicker (black) gasket in your K4073 kit go below the spacer or above?

          • Sorry I didn’t see any pictures.

            The kit includes the flange gasket. It goes between the carburetor and the spacer.

  7. Hi Mike, I have this carburetor

    1BBL YFA Carter Carburetor for Motorcraft 7164SA 2428 62253

    This exactly:

    It does not has the tag number, the stamper number is not clearly marked because of the screw, but it’s says something like 7250

    Which kit is needed?

    Thanks for your time!

  8. I have a 1958 Jeep FC170 with an inline 6 engine.

    On the carb is:

    Carter YF on the body and 1-788 at the base

    Which kit do I need?

  9. I have a Carter YFA on a 75 Jeep. After two or three days the carb will bleed dry. I was in auto repair in the 70’s and early 80’s and we used to flush the carb with some chemical when this occured–I have forgotten what I used. Any help would be grateful.

  10. it appears that there is 2 copies of the video 1 link, but i could not find one for video 2. What is the link for the second video so i can view it.

  11. Yep been there done that but I took my time and didn’t drop anything. She is running like a champ now. Would the bowl vent lever being like a 1/4″ away have any effect on a rich mixture or do you think the float just wasn’t right?

    Thanks Mike will stop bothering you know. LOL

  12. Ok I got it. Pulled air horn and found nothing in idle tube. Doubled checked pump and metering rod and adjustment look good; nothing binding. Went ahead and adjusted float just a little to allow less fuel in bowl. Noticed after putting it back together that the bowl vent lever was not in contact with the bowl vent arm as my service manual said it should be; adjusted to correct position. Now the idle mixture screw is working and rich fuel smell is gone. Took her on a maiden voyage and ran great! Thanks Mike.

  13. Mike
    Was thinking about this issue and looking at exploded views of yfa. I am not understanding how a clogged idle tube would cause an idle rich condition and idle mixture screw to have no effect on idle when turned in? Would think a clogged idle tube would cause a lean idle condition. School me please. Thanks

  14. Ok thanks mike for the fast response. I already changed the float with new during rebuild. Just to verify the idle tube is the same thing as the low speed jet? Thinking back on the rebuild I blew out all passages in carb bodies and throttle body but I am positive I did not check the low speed jet for any blockage before putting it back in.
    Can I remove the top off carb while still mounted to engine and remove the low speed jet to check? Thanks for the great help Mike!

  15. Hey Mike, This is a little long winded but please bare with me.
    Bought an 84 ranger from original owner that had sat inside for a few years. He did state he thought it had carb issues when I got it. Started truck and it ran very very rough, rich and would not idle. Replaced plugs, cap, old cracked vacuum lines. Rebuilt the YFA Feedback carb with kit and installed new float as well following you’re YFA videos and the instruction sheet.
    Carb back on fired right up, ran much better and idled. Set Fast Idle & Curb Idle per manual and specs on sticker under hood. Problem I am having is its still running rich. The mixture screw was only turned out 1.5 turns when I removed from truck so I put it back that way. This evening I decided to bring truck up to operating temp. and then slowly turn mixture screw in. This had no affect on idle at all; even all the way seated it stayed idling at 850. The mixture needle end of the screw did look like it had some light wear with 3 distinct stagarred dark lines around tip. I did not touch the adjustment on the metering rod. Just removed as complete assembly during rebuild and left alone after reinstalling it. Float was adjusted per instructions. Throttle response is great and will idle ok at 800 – 850 just rich smelling and a little smoke unless I hit the throttle which creates more smoke. My question; (yeah I know finally) Would a bad idle mixture screw be far enough gone to have not effect on fuel/air mixture or do I have something else going on?

    Thanks Dave from Indiana

    • The idle mixture screw isn’t your problem. You are probably getting too much fuel. Check the float level. Make sure the float isn’t rubbing anywhere. Run thin wire down the idle tube. They have very small holes and get plugged easy. If your float is a nitrophyl consider changing it out. It may be absorbing fuel.

      At idle look into the bore. Is fuel coming in from the main discharge hole. You should get fuel here only when you press the accelerator.


  17. Hey mike. I just rebuilt my YFA following your video as I went. Thanks for that. I haven’t worked on a carb in over a decade. Anyway. Now when I hit the accelerator it doesn’t pick up speed. It feels like the carb is getting loaded with fuel and then it eventually back fires. Any thoughts on how to fix this. Thanks

  18. Hello, i have a carter yf 740S in an international L110 from the 51. the problem is that it is running rich and throwing black smoke, i dont know what can be the problem, any advice would help me.
    thanks and sorry for my english (in my country we speak spanish)

  19. Mike, It looks like part 2 is really part 1 again. Any chance you can get that updated to show the real part 2? It would be really helpful.

  20. hey mike is there any chance you might have a 59 willys jeep 226 engine yf carb,the crb i have now has been butchered up i need a good reliable one doesnt has to be show quality, thanks again

  21. I have a Carter 1 bbl on a ’83 Ford Bronco that came to me as a complete basket case. Everything is re-assembled now and I already put a kit in my carb and I’m now hooking up vacuum lines. The vacuum map shows 3 ports on the carb however the carb is not stamped and it’s not clear which is which. The map ID’s them as “e”, “s”, and “3”. There are three ports on the carb, one in the base, one on the linkage side of the float bowl, and one very near the top in the top half. Can you tell me which port is which because I’m not finding that info anywhere. Thanks

    • Unfortunately, I have not clue about where the vacuum lines go. I haven’t installed a carburetor on a vehicle in so many years, that I have forgotten. Hopefully someone reading this will know where to get this information.

  22. I have a 1984 Ford F-150 with a 4.9 L straight six cylinder engine. In June I ordered and received from you a rebuild kit #4317 for a Carter YFA one barrel carburetor. After rebuilding the carburetor, my truck runs absolutely great. Thank you for the kit and the very informative videos.

    I do however have a question. Before I rebuilt the carburetor I was having some problems with the throttle sticking when trying to accelerate. It was not a big problem and I thought that I just needed to replace the throttle cable. After rebuilding the carburetor this last summer, the problem completely went away for a short period of time. But after driving more, the problem reoccurred and has gotten progressively worse. Now it is to the point that it actually gets stuck when accelerating and you can not get the truck past 35 mph. It only does this when the engine is running. If I cut off the engine then there is absolutely no binding in the linkage anywhere when you throttle the carburetor. Also I can unhook the accelerator cable and the problem still occurs, (when the engine is running) so it has nothing to do with the cable. And I do not see any evidence of the linkage binding.

    Do you have any ideas as to what is going on?

    • This is a tough one. I would have to be there and physically diagnose this in order to have an educated opinion. I asked Jeff, my consultant the same question and he answered as follows:

      All I can do is to make a few random guesses.

      When the engine is running, the diaphragm is seated unless under load. Could the problem have something to do with diaphragm / stem position? Something would have to be awfully worn / loose / mis-assembled for this to occur.

      Again, when the engine is running, a certain amount of vacuum is exerted upon the throttle plate. Could it be sufficient to cause a loose throttle plate to bind in the bore? I don’t know. Could the throttle shaft have sufficient wear to cause such a bind? Only the customer would know.

      Could an idle shut-off solenoid or a throttle position sensor somehow be holding the throttle back when the engine is running, hence the device is energized?

  23. Hi! two years ago, a big truck crashed against my 1977 six cylinder Ford maverick that is using the carter yf/yfa carburetor, the crash caused a fire that melted all the plastic parts inside the engine compartment; now, two years after, the rebuild task is almost accomplished, the problem is that the vacumm hoses and pipes that are connected to the carburtor, were melted by the fire, and I am looking if you have of may know about where to connect that hoses, the carburetor rebuild is done and the engine starts, but if I press the pedal, the engine dies, somebody said that there is much air entering, may you help me with this trouble?, please send suggestions and pictures/diagrams to
    thanks in advance, ofsalcido,

  24. I have a Carter YFA from a 1981 F-150 on a 4.9L L6 engine, it is a model 7398 or E1TE-ANA from the original carb’s tag. The one on the truck now is a remanufactured Autoline #C6247. I have the truck in Denver now at ~5600ft altitude and am looking for a good starting point in getting the right jet/metering rod combination. If you can point me at the right parts I’ll get them ordered from you right away. Thanks!


  25. Pingback: Bringing back a 1982 F-100 - Page 2 - Ford Truck Enthusiasts Forums

  26. Mike, I have a 1985 Jeep CJ7 with the 2.5l engine. It runs well but also rich. The carb number is 7344. It has 8525 stamped on the metering rod and 410 stamped on the main jet. I would like to get it leaned out and need some help in picking the right size jet and metering rod. Thanks.

  27. Mike:

    My mechanic/friend recently had one of his young technicians install a Carter YF Carburetor on my 1977 CJ-7 Jeep. The knucklehead technician, who is probably not familiar with carburetors, apparently removed the coil spring from the choke housing along with choke parts. I believe he did this since he did not understand that the automatic choke works by heating the coil spring via the heat core tubing that runs from the intake manifold to the port on the carburetor. He also left the port open (he did not put on the available choke tubing) on the carburetor and you can hear it whistling Dixie.

    I plan to bring the Jeep back to the owner/mechanic who apologized for not catching this boo-boo. To insure that I’m correct, in your opinion the automatic choke should be set up and not bypassed. Correct? I have been researching how the 1975-1977 YF Carburetor with Automatic choke works. I want to insure that the owner of the garage fully understands the importance of not bypassing the automatic choke. Am I correct in insisting that that the choke coil and choke heat tube should be put on the YF Carburetor even if I’m in a warm climate, e.g., Southern Texas.

    I’m basically asking for additional information I can impart to these people.


    K. McDee

    • You cannot run with the choke disconnected. The carburetor will not operate as it should. Your carburetor will either flood, or it will be very difficult to start, even in mild climates, depending on what they did to the choke valve.

      • Hello Mike I’m working on a Carter YF 2094s of off a 1954 Kaiser that proablly has bin apart numerous times. (This is a little hard to explain.)The problem is the linkage for the accelerator pump and metering rod is baffling me. The problem is at idle the metering rod is out of it’s seat compeletly and the the accelerator pump is not pushed down at all. On your diagram page 6 of YF carbs showing early and late production is the hole on F and G the same size? The hole in the pump lifter link at the top where G is pictured is larger than F contact link, so when you open throttle nothing happens. That is how I got it but I think pump lifter link is incorrect. Any help would be appreciated. Thanks

      • Mike: I agree with your comments above. I’m trying to determine why someone would remove a fully functional part and not advise me. Well, it’s back to this shop owner to tell him to properly fix the choke.

  28. I don’t know which kit to buy. I have a ’77 Ford f150 with a 33 i6. The carb says “Mfd by Carter for Motorcraft.” There are several numbers in several places, but not on a vertical shaft. They are all horizontal. On the front of the bowl is a 6 with 2228 beneath it. On the river’s side there is the number that looks like 70518A with the number 2402 beneath it. Also on that side, but on the bowl. is the number 2430. How do I know if this is a yf or yfa-or what-and which rebuild kit should I get?

  29. Hi Mike. Looking for a spring loaded needle and seat assembly with .076″ orifice for my Carter YF 938SA. I didn’t see it in parts list. Can you help me?

  30. Do you know where I can find the nylon insert that sits between the throttle shaft and the throttle position sensor on a Carter YAF carburetor? The insert drives the TPS in relation to the throttle.

  31. I have a Carter YF ..from a 1951 Chevy and my throttle plate shaft is leaking..can it be repaired ..or can you sell me a new or god used one..thanks..Mitch

    • Your throttle shaft is only leaking because the fuel is flooding over and going out anyplace it can find. You need to rebuild your carburetor. Go to our website and enter in your carburetor number in the search box. The correct rebuild kit will be listed.


  32. Mike: I have a 1978 CJ-7 Jeep with 258 I-6 engine and YF carburetor. I removed the YF carb, and attempted a Weber K550, 32/36 DGEV conversion. In short, does not work. So, I plant to go back to the original one barrel YF Carburetor. My question is do you have linkage kits for the YF Carburetor? I think I have most of the remaining linkage with the YF carb, but may be missing something like the Throttle Belt Crank Rod. I can take pictures and send. Also, do you have any directions on setting up the linkage on the Carter YF Carburetor for the 78 CJ-7 Jeep (or 1975 thru 1977 Jeep CJ7’s). Thanks for your patience.

    Ken McD…

Leave a Reply

Your email address will not be published. Required fields are marked *