Okay, Got a new Holley 4781 and have some issues
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Okay, Got a new Holley 4781 and have some issues

  1. #1
    Senior Member Itsahobby's Avatar
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    Default UPDATE:Okay, Got a new Holley 4781 and have some issues

    Got it all together.
    I was getting 8 Hg, so I switch to 3.5 Hg power valves front and back.
    I change the primary jets to 75, they were 80, left the secondaries at 80.
    Float levels were not even close from the factory. Set them to just a dribble. Might have to re-adjust since my drive-way is slightly angled.
    Adjusted the mixture screws to highest vacuum.

    The motor is way more responsive, will see what she does this weekend on the water, weather permitting.
    Thanks
    --Jerry

    I purchased a holley 4781 and starting check the transfer slot settings, butterfly movement and general checking.
    1. It has a lot of solvent/gas in it. Enough to squirt me in the face when I rotated the throttle. I've bought a few carbs before and I can't remember any of them with solvent in them.
    2. The secondary butterfly sticks when returning from full throttle. There is a snap, then they close.
    3. The transfer slots are completely covered by the butterfly.

    I'm going to call Holley tomorrow, but have any one got a brand new carb that had gas in it?
    Any input would be appreciated.
    Thanks,
    Jerry
    Last edited by Itsahobby; 10-06-2013 at 06:51 PM. Reason: update

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  3. #2
    gn7
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    Quote Originally Posted by Itsahobby View Post
    I purchased a holley 4781 and starting check the transfer slot settings, butterfly movement and general checking.
    1. It has a lot of solvent/gas in it. Enough to squirt me in the face when I rotated the throttle. I've bought a few carbs before and I can't remember any of them with solvent in them.
    2. The secondary butterfly sticks when returning from full throttle. There is a snap, then they close.
    3. The transfer slots are completely covered by the butterfly.

    I'm going to call Holley tomorrow, but have any one got a brand new carb that had gas in it?
    Any input would be appreciated.
    Thanks,
    Jerry
    Never had a new carb arrive with anything in it. I have to imagine UPS or FedEx would shit if they new there was any form of hydrocarbon based liquid in the thing.

    hard to say why the transfer slots are covered. Have you tried to close the blades to expose them?



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    Senior Member Itsahobby's Avatar
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    Yes, I made sure the choke is open, also. The primary slots look right sometimes, but after I open and close the throttle the butterfly stops at different angles until I tap the linkage a bit.
    I bought it through summit, but it almost looks like a used carb someone put on and took off.

    Quote Originally Posted by gn7 View Post
    Never had a new carb arrive with anything in it. I have to imagine UPS or FedEx would shit if they new there was any form of hydrocarbon based liquid in the thing.

    hard to say why the transfer slots are covered. Have you tried to close the blades to expose them?

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    Senior Member Itsahobby's Avatar
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    Just checked my receipt from Summit and it says:
    "All Holley carbs are flow tested before they leave the factory. Holley uses a non-flammable mineral spirts that, on occasion, a small amouns might still be found in the accelerator pump diaphragms.
    That explains that, but I wouldn't put a match to it.
    Still need to find out about the secondary sticking when releasing from full throttle.
    Thanks for your help,
    Jerry

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    gn7
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    Quote Originally Posted by Itsahobby View Post
    Yes, I made sure the choke is open, also. The primary slots look right sometimes, but after I open and close the throttle the butterfly stops at different angles until I tap the linkage a bit.
    I bought it through summit, but it almost looks like a used carb someone put on and took off.
    It sure sounds like it was used. Holley does not ship wet carbs. I wouldn't be surprised if they don't even test them with any fluid.

    Holley is slipping when it comes to their transfer slot location in the base plate. But if the blades sometimes fall in the right spot, and other times it not, something is wrong. Sometimes its in the secondary link bar that needs tweeking.



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    Senior Member Itsahobby's Avatar
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    Just of the heck of it I soaked some of it up on a blue shop towel, took it outside and lite it on fire. It burned for a pretty long time. LOL
    I was looking at the link bar, I think I was anyway, and it is almost like there is too much pressure against the plastic cam(friction). Once it gets past that point, it snaps close. I'll call Holley's tech support tomorrow and see what they have to say.
    Pretty beat right now, mess of stuff going on, on the home front.
    Going to call it a night.
    Thanks, a really do appreciate it.
    --Jerry

    Quote Originally Posted by gn7 View Post
    It sure sounds like it was used. Holley does not ship wet carbs. I wouldn't be surprised if they don't even test them with any fluid.

    Holley is slipping when it comes to their transfer slot location in the base plate. But if the blades sometimes fall in the right spot, and other times it not, something is wrong. Sometimes its in the secondary link bar that needs tweeking.

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    Senior Member ol guy's Avatar
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    Quote Originally Posted by Itsahobby View Post
    I purchased a holley 4781 and starting check the transfer slot settings, butterfly movement and general checking.
    1. It has a lot of solvent/gas in it. Enough to squirt me in the face when I rotated the throttle. I've bought a few carbs before and I can't remember any of them with solvent in them.
    2. The secondary butterfly sticks when returning from full throttle. There is a snap, then they close.
    3. The transfer slots are completely covered by the butterfly.

    I'm going to call Holley tomorrow, but have any one got a brand new carb that had gas in it?
    Any input would be appreciated.
    Thanks,
    Jerry
    First off how did it squirt you in the face? Were you holding it over your'e head and looking up the throttle plate? Second would be at times the butterflies need to be adjusted for a flush close. If you had the carb held somewhat level and got squirted in the face I think you have more than one issue! M

  10. #8
    Senior Member Itsahobby's Avatar
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    I had the carb upside down, looking to see why the secondaries were hanging up.

    Quote Originally Posted by ol guy View Post
    First off how did it squirt you in the face? Were you holding it over your'e head and looking up the throttle plate? Second would be at times the butterflies need to be adjusted for a flush close. If you had the carb held somewhat level and got squirted in the face I think you have more than one issue! M

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    I'm with GN--secondary link bar. I had one that was rubbing on the throttle plate shaft chingy'. Only did it after WOT. Holley offers some kind of "pro series" secondary linkage. Prob over priced piececs of shiney rods/links.???

  12. #10
    Senior Member Itsahobby's Avatar
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    Default High spot on the accelerator pump cam

    Looks to be a high spot on the accelerator pump cam. If I press down on the accelerator lever, slightly, and open the throttle it does not drag or snap.
    Thinking about sanding it down a bit to smooth out the transition.
    --Jerry

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    S&S
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    You said "it is almost like there is too much pressure against the plastic cam(friction)" .. Is that at the end of the stroke only?? Could be the pump arm is not adjusted properly. Almost sounds like it might be binding up (bottoming out) in the WOT position.

  14. #12
    Senior Member Itsahobby's Avatar
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    It's actually after it comes off WOT, about 1/4 inch on the cam.


    Quote Originally Posted by S&S View Post
    You said "it is almost like there is too much pressure against the plastic cam(friction)" .. Is that at the end of the stroke only?? Could be the pump arm is not adjusted properly. Almost sounds like it might be binding up (bottoming out) in the WOT position.

  15. #13
    Senior Member Itsahobby's Avatar
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    Default Holley tech. says

    The hesitation on the accelerator pump is common and not an issue.
    On the solvent, he said they try to get it all out after flow testing, but don't always.
    On the transfer slot, check it with the choke open, which I did, and it should be fine. I'm going to take a look at this again and make sure it is going back into position after releasing the throttle.
    Thanks for all the input.
    Jerry

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    I have had the same issue with the 4781. The 50cc squirter on the secondary side hits a "flat spot" of sorts and due to the friction it sticks just a little. I did a little "custom" work on the plastic pump cam as well as gave it a touch of moly grease and it was not a problem after that. If you have a choke on that thing it very well could be the fast idle cam in the choke mechanism that is holding the primaries open as that is what it is designed to do. Take a close look under the choke mechanism and I bet you will see how it works and that it is your culprit. Just my un-educated guess anyway.

    Paul

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