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.
YF Carburetor

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 Carburetor

Older YF Identification
Carter YF Carburetor

YF Pump Discharge Check Valve Problem
YF Acceleration Stumble YF-938SA, WillysCarter YF Carburetor CatalogCarter YF Carburetor ManualYF Manual 1968-69





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.

To figure out which check ball goes in which hole, assuming you have two different sized check balls, look into the bottom of the holes and you should see which hole is bigger than the other. Simply place the bigger check ball in the bigger hole.

Be sure each hole has a trough for the check ball to sit into. The check ball has to stop the fluid from going in one direction, so it will need to sit into a beveled edge hole. When there is no bevel, then it probably doesn’t need the check ball.

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.

 

27 thoughts on “Carter YF YFA Carburetor

  1. 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…

  2. 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.

      Mike

  3. 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.

  4. 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?

  5. 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?
    Thanks,
    Tony

  6. 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.

    Thanks,

    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.

  7. 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.

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

  9. 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!

    John

  10. 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 ofsalcido@gmail.com
    thanks in advance, ofsalcido,

  11. 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?

  12. 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.

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