Holley 1920 Carburetor

Holley 1920 Carburetor CatalogFind the correct Holley 1920 Carburetor Kit.

There are several carburetor kits for the Holley 1920. Please be sure to match up your carburetor number with the numbers listed with each kit.

Here is where the carburetor number can be found. The complete carburetor number may not be on the carburetor. Example R-4161A. R simply means carburetor, 4161 is the list number and for out purposes is what matter most. A simply means it is an assembly. 1A would mean a modification was made. In general look for the list number. This will usually be 4 numbers.
Holley 1920 Identification

Holley 1920 Carburetor Identification

The Holley 1920 carburetor generally used the Nitrophyl type of float and should be replaced anytime you do a carburetor rebuild. The Nitrophyly float tends to absorb fuel over time and can cause the carburetor to flood over. Unfortunately these floats are no longer being produced, but we were able to obtain several of these floats.

Free Holley 1920 Manual – 1968-69

Holley 1920, 1940, 1945, 2210, 2245, 5200, 5210, 5300 Carburetor Manual

Watch a video about troubleshooting the Holley 1920 problems.

35 thoughts on “Holley 1920 Carburetor

  1. Do you happen to have a fast idle cam and screw for a 1920 (off of a 1966 slant six 225). Mine has somehow disappeared (I think after some guy worked on it).

    Thanks a million

    • You should get that figure out of your motors manual. We do not have a list of fuel pressures, but should be around 4 – 4.5 lbs.

      No float available for the 1920

  2. That funny cuz i have a new 1920 carb new in the box been sitting in storage for 25years along with A bunch of other never used new in the parts.

  3. 66 Dart 225 automatic 1920 Holly. Starts great when cold. Will not start without priming carb when warm. Accelerator pump will not pump. This is one of those rebuilt carbs from auto parts stores several years ago by owner that never ran until bringing to me recently. (cross wired, miss adjusted valves) Disassembly of carb I can not find any kind of check valve to make the accelerator diaphragm pump. Can you show economizer plate check valves so I can compare? I believe parts are missing!

  4. I have a 1965 Dodge Dart 225 with a one barrel Model 1920 Holley carburetor. Need a fuel bowl gasket and a base gasket. Not sure which repair kit to get? There are two sets of numbers that have been stamped into the carb body/housing near fuel bowl. First set of numbers is 4712, the other set of numbers placed just below first set is 0635.

    There is another set of numbers placed on the carb body just below where the fuel line comes in.
    That set is 12R-4328-B

    Would Holley Carburetor Repair kit # K458 be the right one for my carb?

  5. I have a 66 Dart 270 that won’t idle after it’s warmed up and the choke is opened. I tried rebuilding it with a high quality kit, but it didn’t seem to help. I’ve checked every potential source for vacuum leaks and detected none.

    When I’m driving down the highway it runs pretty well, but the exhaust fumes are horrible. Also when I fire it up sometimes it will leave a black spot under the exhaust.

    Any ideas?

    • My guess is that it is flooding, which would result in fumes and/or black smoke. Did you test the float. It might be sinking. Assuming your electrical system is good then the carburetor is getting too much fuel. Bad float, needle & seat not shutting down, or too much fuel pressure (the least likely).

  6. Thanks for the response. I’ll purchase the body as you suggest. The list number I have is not shown on your list for the 100-14 float. Shall I assume it won’t work on my 3225-S? Please let me know so I can place my order. Thanks again.

  7. When you say metering block, I assume you mean the economizer body? I did not check the flatness of that, but assumed that the gasket between it and the carb bowl would resolve any flatness issues? One thing I did think of and it could be the issue is that when I disassembled the carb I found some RTV or sealant type of material on the throttle shaft, which may have been put there to mitigate a vacuum leak at the throttle shaft. I did not notice any discernable “slop” in the shaft, but I am now concerned that there could be a vacuum leak there causing the car not to idle. Can I simply have the throttle shaft repaired with new bushings installed? I have read that that could be done. Is it worth trying or should I simply start looking for another 1920 body? I also noticed that the pump plastic actuator seems quite worn. Could that have any relation to the lack of idle when warm? I see that you sell a replacement as well. May need to purchase that if you think it could resolve this idle issue.

    • You should test with carb cleaner spray around the throttle before you throw th.e carburetor out, but I suspect somebody had a problem, or the sealant wouldn’t be there. Frankly, while the idle would be rough, I haven’t seen them so bad that the engine would die. The actuator isn’t the problem. A worn actuator might result in a hesitation on throttle up. Our actuator is for the flat stem type of accelerator diaphragm. The round type is not available any longer.

  8. Thanks for your prompt responses, videos and quick delivery of your kits. I have tried all of the things that you suggested, and the car still won’t idle after it warms up a bit. The car starts fine when cold and runs well, but as it warms up, it will not remain running. It does not seem to be flooded, and I don’t smell fuel when it dies. I should also state that the car ran fine before the rebuild with one exception, that being that it would hesitate from a stop every time after it was warmed up. The card had a complete tune up as well prior to the carb overhaul. I did find that when removing the carb for the first time, the two retaining bolts were only finger tight which I thought was odd. Anyway, I have now had that carb off and on at least 6 times, and cannot find the problem. It seems to me that it must be a vacuum leak? I sprayed carb cleaner all over and could not find any real change in RPM though. Any thoughts on a possible issue with the idle circuit itself? My kit did not come with the caps that you refer to in the video that are part of the economizer body. I did verify that there is a check ball in the one passage, and something moving (I assume the check valve) in the other passage. I also confirmed that the power valve ball and spring were in place.

    After the car is warmed up, I have to continually increase the RPM to keep it running, and it times it will backfire through the carb. I also removed the economizer diaphragm and peered into the bowl. The level did seem high, but not dramatically. I roughly measured the wet fuel level at 16/32, but the car is on a slight incline. I realize that that is high and it should be 27/32 but don’t see this as the root cause of the problem. I do intend on replacing the float however, I am not certain which it is. According to Walker since I have a 1963 Dodge Dart application, it should be 100-86, which they have in stock. That float is supposedly 7.5g new. The other option is the 100-14 which, I believe that you sell. That float is supposedly 12.5g new. My float is marked “Holley C106” from what I can tell, and weighs 13.2g, so I am not certain which float to get. Is it possible that it is that soaked to make it almost double the float weight new? Any thoughts?

    I am about ready to simply order up a rebuilt one on line somewhere, but am not certain it is the carb for sure. Although the carb is the only thing that I changed. I did check the two vacuum hoses that attach to it, and found no obvious leaks. Anyone have any ideas?

    • Walker may indicate that they have the 100-86 in stock, but these are discontinued. I just verified that. I need to find a 100-86 (new or used), then do a video showing the difference in the two. I don’t know if I have any around yet.

      Try to fix the carburetor problem yourself 1st. Chances are good that a replacement won’t be what you would like. I get quite a few people grumbling about how bad the rebuilt exchange units are out there, especially the 1920 because of the bad throttle shafts that they have.

      • I have tried all suggestions to fix the situation. Any other thoughts? Is it possible that rebuilding the carb identified some other issue, like low voltage from the alternator, or possibly “tight” valves? Not sure what to do next.

        • Forgive me if I repeat something I already have gone over. I get so many inquires, I struggle to remember every one.

          It is very hard to diagnose this type of thing without being in front of the car, but I just re read the problem and it seems the engine was running fine before the rebuild, so I would tend to think the problem is in the carburetor. By any chance did you check the flatness of the metering block. We usually grind the back flat (a flat file would work too). They tend to get warped over the years and gasoline can leak out the back and back into the float bowl.

          What do the spark plugs look like after all of this. If they are black, then too much gas. White indicates not enough gas. What I’m trying to get to is whether the carburetor is sending too much fuel, or not enough.

          Just came to mind. How is the throttle shaft? The 1920 carb is notorious for wearing out the shaft. When you spray carb cleaner around the throttle shaft does it change the RPM. If it does then that would be the same as a vacuum leak and you will need to find another carburetor. Not much chance of find a throttle shaft.

          Review the exploded view on the instruction sheet to make sure you got all of the parts back where they should be.

          I’m going to ask one of my consultants if he has any ideas also.

  9. Thanks for the quick response, and a video no less! Wow. As it turns out, I don’t seem to have any of the problems that you specify. However, I am concerned that the float needs replacement. I set the dry level as specified in the rebuild kit. However, I found that the wet level is around 16/32, and from what I read on the web, it should be 27/32, which would mean that I have too much fuel in the bowl. I know that you sell a float for the 1920, but my carb number is not listed there. I have a “2978, 3225-S”. From what I can tell the two floats are significantly different in weight despite the fact that they look alike. I found that the Walker Products web site shows two parts, the 100-14 which you have, and a 100-86. The 100-14 supposedly weights 12.5g and the 100-86 only 7.5g. I don’t have a scale to weigh mine. The pictures look identical. My 1920 is on a 1963 Dodge Dart GT with a 225 CI 6 cylinder. Do you think the float you sell will work, and that it may be the root of the problem? All other test that you suggested pass. Thanks for your help.

  10. OK, bought the 1920 rebuild kit, #458 I believe, got it quickly and cleaned and rebuilt the carb. That was easy. The car started right up, then once it began warming up got rougher and rougher on the idle, until it just would die. I took the carb off again, and checked everything again, made sure to blow through all passages etc, checked the float height as well. Thought that the idle circuit may have been plugged with cleaner or something, and blew out the passage via the jet hole. Put the carb back together and the same thing happened. Any thoughts? It just won’t idle at all. I checked for vacuum leaks as well.

    I should mention that before the rebuild the car was running quite well except for a stumble at the hit of the throttle after it was warmed up. If you didn’t feather the gas pedal the car would die when starting from a complete stop. Any help would be appreciated.

  11. Great site. Unfortunately I am not available to determine what rebuild kit I need. I have a 1963 Dodge Dart GT, with a 225 CI slant 6. I expected that I needed the Holley 1920 kit, but after reviewing your site, I found the part number on my single barrel Holley. It is as follows: 2978 then below that number is 3225S. Please help me determine what kit I should use for this carb.



  12. Hey mike. I just rebuilt a Holley 1920 using your kit (great kit, high quality and complete). When I took the carb off to rebuild it, the vehicle was running but under load while going up hills, it would shudder and start to cut out. I replaced coil, plugs, wires, rotor/cap, but figured a carb rebuild was in order after that didnt fix it. I soaked the carb, cleaned it really well and installed your parts. When I put it back on the vehicle, it started right up, ran a bit and then died. I took the air cleaner off and tried to start it again but noticed that fuel was flooding into the carb. I made no changes to to the floats so I am not sure why it would change so significantly. Any thoughts before I tear into it again?

    • The float is a nitrophly and should be replaced at each rebuild. Unfortunately we only carry a float for some of the 1920’s. None of the 1920 float are being made anymore. Look at this one: http://www.carburetor-parts.com/Holley_1920_Float_p/100-14.htm

      Check to make sure you aren’t getting gas around the needle and seat. Take the carb apart and blow air into the fuel inlet while putting your finger over the seat. No air should be getting into the carburetor.

      The are a few suggestions. Obviously you are getting too much fuel into the carburetor.

  13. I have a 1983 Dodge d150 pick up with a 225 slant 6 out of a mid 70’s dodge duster. The carburetor that is on the engine is a Holley 1920. The engine is very rough and choppy at idle while in gear. And, adjusting the idle mixture screw doesn’t do anything. I am sure that i need a rebuild kit for the carburetor but i cant seem to be able to match the identification numbers that i got off the carburetor with any rebuild kit or carburetor identification on the internet. I have ruled out the ignition system because the spark plugs are all fine (and recently replaced). And the problem is only at idle (once it gets moving, it is fine). I am planing on putting a manual choke on it, too, because i have had lots of problems with the choke stove that it is currently on it. If you could please give me any insight that you have on my situation, i would greatly appreciate it. Thank you

    • A manual choke would have to be manufactured by you. I don’t know of any conversion kit. The 1920 is famous for wearing out the throttle shaft, which will lose vacuum and run rough at idle. Spray some carb cleaner around the shaft and see if the idle smooths out.

      The fact that the idle mixture screws doesn’t change anything can also be attributed to a worn out shaft, but can also be caused by a dirty carburetor needing attention.

      Note that the shaft are no longer available.

  14. I have a Holley 1920. My pickup starts and idles normally and my 3.8L 230 CI L6 runs ok. However, under load (going up a hill and at high temperatures(I live in AZ) the pickup hesitates upon applying throttle and I also have a very slight occassional backfire. When I release or apply moderate throttle the pickup continues to run but not a full power. I checked the ignition side including replacing the coil, distributor (IAT-4416) cap and and points as well as installing a new set of spark plugs with the correct gap. The original plugs were heavily fouled (with black coking deposits on all 6 plugs). I am thinking that the Holley 1920 idle mixture seting is OK because the pickup starts and idles normally and when driving it on flat terrain or downhill I dont experience the hesitation or slight backfire. I am thinking that the fuel mixture is too rich and needs to be leaned out by adjusting the carburator. Could this be the problem or is it the bowl level,, or something as simple as a clogged air filter?

    • Adjusting the idle mixture screws only affect idle, nothing else. Your problem could be a lot of things. Vacuum leak, improper float setting, bad float, or perhaps the main jets. The fact that the plugs are black means there is too much fuel. You didn’t say if you rebuilt the carburetor, but if not, do that 1st. Assuming everything else is correct, then the next thing would be to start changing the jets. Search this site for jets and you should find instructions on how to figure out which jets are correct.


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