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Thread: Holley 4160 - Problem After Rebuild

  1. #1

    Default Holley 4160 - Problem After Rebuild

    Hello all. I'm new here, but don't know where else to turn! I'll try to be brief, but I'm having a serious problem with my 4160 after a rebuild.

    Like I said, I'm running a 4160 with vac secondary on a 258 straight six, on a Jeep CJ7. This is the carb that came with the jeep, but it was running a bit rough, so I decided to rebuild it. After taking it off, I discovered that the previous owner had removed the fuel transfer tube, effectively reducing the four barrels to two. I also discovered that one of the Venturi on the secondary side was broken off, so I ordered a replacement "core" from eBay and a new tube and added it to the rebuild. After cleaning everything and rebuilding / installation, I cranked the jeep and it idled beautifully!

    Now, to the problem. Like, I said, it idles fine. And it accelerates fine. To a certain point. At around the throttle half-open point (I don't have a tach, so I don't know how many RPMs) the engine starts to cough and if I go any further it dies. The vac secondary has not opened at this point, but if I manually move it open a bit, the RPMs will increase, but it starts to backfire. I've done a bit of troubleshooting, but have had no luck. Float levels are OK and I cannot find a vacuum leak, but that's not to say there isn't one. I bought a vacuum gauge today and vac appeared to be normal at idle.

    I don't even know what to check next. I'm relatively new to the world of carburetors! Any suggestions?

  2. #2

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    Well to start the troubleshooting, I would zip tie the secondary linkage, so it can't open at all. That way you know you only dealing with the primary side of the carb. First thing, make sure your timing is right. Check it idle and check it at about 2500 rpm or so. (You really need a tach. Go buy a cheap one from AutoZone, O'Reilly. If for nothing other than troubleshooting.)

    When you say at around half throttle it starts to cough and any further it dies; are you going straight to half throttle from a stop, or is this a cruising along and gradually approaching half throttle that the problem starts to show up? This will help us pinpoint which circuits might be giving you some fits.

    Next, I would free rev the motor to the trouble area. 2000-3000 rpm where ever it happens at. See if you can recreate the problem that way. If you can watch the venturis on the primary side, as long as it doesn't cough or backfire, and look at the spray pattern make sure they both are flowing properly. (Same spray pattern.)

    To check for a vacuum leak you can use some WD-40 with the red nozzle, so that you can pinpoint spray the base plate, throttle shaft assembly area, vacuum hose connections. Put a rag under where you spray to help clean up. It can be a little messy, but is very effective with finding vacuum leaks. If there's a leak and it gets WD-40 in it, the motor will idle down considerably.

    It sounds like a fueling issue, and at that area of your problem it would be the main jets, but I'm suspect to it having something to do with your rebuild. Especially if the Jeep would accelerate prior to the rebuild.

    Did you double check the gaskets in your rebuild kit to make sure they were the exact same? Possible you put a gasket in backwards?

    Just some things to check if the carb would accelerate prior to your rebuild.
    Last edited by 69cam; 12-06-2015 at 11:55 PM.

  3. #3

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    I'll go get a tach tomorrow & troubleshoot. I tried to be very careful when rebuilding to use the correct gaskets, but I'll disassemble and check it out if nothing else works.

    Oh & yes, it doesn't matter whether I gradually approach half throttle, or do it quickly. It dies either way.

    I got to thinking last night, and remembered that when I reassembled using the new "core" that my previous one used a tube to connect to the primary metering block, but the new one didn't have a place for a tube, just a hole. I used the gasket for the type with just a hole, but the metering block still has a cavity for the tube. Could this cause the problem? The accelerator pump & jets work great, but I could be missing something.

    Thanks!

  4. #4

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    I think hardly anyone comes to this website. I bought a Holley rebuilt 500 CFM 4 bbl via the internet. It had a Holley box and all the trimmings. Since my truck was outside, and the weather sucks I took my time installing it. It has the same problem that yours exhibits, and others. The electric choke was spastic, and they forgot to engage the tang in the bimetallic element. I fixed that. It falls on its face when I try to drive it over 1500 RPM. It will rev up to 5000 easily in neutral but when you try to drive it it just dies out once it gets started. I put a new fuel line and filter on the input, and checked the pump. it pumped 5 ounces in 10 seconds, the float bowl on the primary side gets full to the check hole now that I adjusted it. It has #512 main jets in it. I've checked for vacuum leaks with spray, no leaks idles fine. I think maybe they have beginners checking these things, I don't see how it could pass a flow test like this.

  5. #5

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    I think hardly anyone comes to this website. I bought a Holley rebuilt 500 CFM 4 bbl via the internet.
    Not sure this is a valid statement but from a carb standpoint, yes, their usage is diminishing. They are becoming a more select usage. Purist, racing, stock, restoration etc etc. Buying from the internet does not guarantee anything. If you mean you bought from Holley or and authorized reseller that is one thing, but to just make a statement "I BOUGHT FROM THE INTERNET" is to somehow mean it's brand new not rebuilt or guaranteed defect free, would be a bad assumption on your part. Just an example I bought GM BBC Aluminum Valve Covers from Summit Racing about 4-5 months ago. I just got my motor up & running about 3-4 weeks ago. I have a slow oil leak that only appears on the "L" & "E" of the Chevrolet on the valve cover. I took the cover off and used my air hose to blow from the inside, and it's weeping oil. Porosity issues. They are super small, about the size of pinhead. Crap happens.

    It falls on its face when I try to drive it over 1500 RPM. It will rev up to 5000 easily in neutral but when you try to drive it it just dies out once it gets started. I put a new fuel line and filter on the input, and checked the pump. it pumped 5 ounces in 10 seconds, the float bowl on the primary side gets full to the check hole now that I adjusted it.
    I'm betting you are either having an issue with your accelerator pump/linkage not being adjust properly, or a fuel delivery issue. Air is almost always there & constant. For it to just fall on it face at such a low rpm is probably a lack of fuel. If it was over fueling at such a low rpm, you would see black smoke and it would foul a set of plugs fairly quick.
    You can't measure fuel by how much it flows over time. You need to have a pressure gauge, and it needs to be able maintain a pressure of 5-7 psi.

    I think maybe they have beginners checking these things, I don't see how it could pass a flow test like this.
    A flow test only on shows that a carb flows the amount it's rated for. In this case 500 cfm. The assumption here being that every thing from a fuel delivery standpoint is working properly.

  6. #6

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    I bought it rebuilt from Holley. I have about 55 years of driving carbureted engines. I'm going to go out and pull the carb off, and inspect the back float bowl. I took off a QuadraJet which performed very well, except it was a bear to get through emissions at idle due to the fact that it was an electrically modulated unit which the previous owner had disabled.

    The engine & electric fuel pump all worked through the entire RPM range as far as smoothness & performance. I do not want to change the timing because it was and is spot on, and you don't do two different things at a time. If you have engine problems, you fix the new system 99% of the time.
    I appreciate you responding to my posting, but I'm very certain this carburetor has issues.

    As for your porosity issues, when we manufactured castings that were not exposed to EXTREME heat and had minor porosity issues, a government approved repair was anaerobic sealant, in other words, Super Glue. If it's a stamping, the press may be over extruding the metal in the area of the logo, which should extend to the entire model line.

    As an addendum, the electric choke was not working properly either. So I took the side cover off, and they had missed the tang with the loop in the end of the bimetallic heated strip. Does not instill much confidence finding that. Oh well, back outside, take the front tires off and drop it down enough to work on it again.

  7. #7

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    Well poop! I removed it again, removed front & rear float bowls, blew through the main jets & secondary block off plate. I reassembled it, checked the float settings and reinstalled it. I inspected the gaskets and checked the adapter for security. Both accelerator discharges work well. It still does the same thing. It starts quickly whether cold or warmed up. It idles smoothly. It will rev to 5000 out of gear. It goes into drive and you can drive at idle or slightly above idle, but the minute you go above 1000-1500 RPM it shuts off. Falls on its face. Quits. If the motor has no load on it, it runs like it should but it won't pull the truck. Every carburetor I have ever had with this type issue, was not getting fuel in the run circuit. As soon as it transitions to the run circuit, it absolutely stops running.

  8. #8

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    I pumped two gallons of gas from the tank into a clean bucket, There is no water indicated. Will Holley take a carburetor back to check it out? Is there an annular ring to pull fuel at run? I have feathered the carburetor trying to exceed 1500 under load and it won't run past that in gear. It also dies if you put it in drive with your foot on the brake and try to accelerate much over idle. It idles great in gear but will a absolutely not pull the vehicle.

  9. #9

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    Quote Originally Posted by billnorman View Post
    Well poop! I removed it again, removed front & rear float bowls, blew through the main jets & secondary block off plate. I reassembled it, checked the float settings and reinstalled it. I inspected the gaskets and checked the adapter for security. Both accelerator discharges work well. It still does the same thing. It starts quickly whether cold or warmed up. It idles smoothly. It will rev to 5000 out of gear. It goes into drive and you can drive at idle or slightly above idle, but the minute you go above 1000-1500 RPM it shuts off. Falls on its face. Quits. If the motor has no load on it, it runs like it should but it won't pull the truck. Every carburetor I have ever had with this type issue, was not getting fuel in the run circuit. As soon as it transitions to the run circuit, it absolutely stops running.
    Hey Bill, so as a vehicle is idling the very first circuit it uses to get going is the transfer circuit and accelerator pump. Here is a quick video of how to adjust the accelerator pump linkage. The transfer slot is non adjustable (well not with out MAJOR SURGERY). I'm not saying yours is not working but it needs to be adjusted so that as soon as you barely touch the throttle it should instantly squirt fuel. If there is a delay it will bog/die. Free revving in neutral has very little to no load on it, so its not a good test. Also, make sure your idle mixture screws are adjusted properly, If your lean it will also bog out.

    Below are a couple of videos, take a quick peak and confirm your carb is adjusted in the below manner.

    Accelerator Linkage adjustment
    https://www.youtube.com/watch?v=k-Nx5HEzvlY

    Idle Mixture Screw Adjustment
    https://www.youtube.com/watch?v=UPGLUsW5ZeE

    Below is an not scale picture of when circuits are activate while driving.
    Click image for larger version. 

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    I want to show you that the boosters don't start flowing fuel until about 1800 - 2200 rpm area. Below are a few videos demonstrating this. The booster are fed directly from the main jets well, which is fed directly off the main jets. So your main "running circuit" does not come into play until well after the transition phase. It requires negative pressure to draw fuel through the boosters. The primary function of the accelerator pump circuit is to provide enough fuel to the motor until there is enough air flow (negative pressure) to cause the mains to start flowing.

    Booster Delay
    https://www.youtube.com/watch?v=chNqanBA8G8
    Last edited by 69cam; 03-03-2016 at 10:04 AM.

  10. #10

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    Are size 512 main jets sufficient for my 4.3L engine with this carb?

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