Help with Nelson pop off
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Help with Nelson pop off

  1. #1
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    Default Help with Nelson pop off

    I have a 1984 cp tunnel with what appears to be a "nelson" pop off valve. I want to be able to use the pop off at the end of each pass to aid in shut down. What mods can I do to achieve this goal ? Would there be any be any benefit in modifying it to work with co2 ? I spoke with Jerry Hicks , the owner of "Hot Tub" last year & it seems like he said it would end up blowing the top off if I used it repeatedly , without modifying it somehow . I installed the pods middle of last year & they made a world of differance. Appreciate any help..........Rick
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    Amber Racing Services BUSBY's Avatar
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    Yeah ... that's a Nelson valve. In it's current configuration, like Jerry said, it will grenade the cap on the top of the piston after a while.

    You can make modifications to it and convert it back to a co2 system (Melluer sp?) set up. I have one that is a co2 system that I can post pics of. It's real old school and would probably cost more than buying a new Mills valve to convert back.

    If you could rig up your own co2 deal to open and close the piston, it might be better than the original or Nelson design.

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    I've hit the button on this system 3 differant times & it has failed to pop off each time. That's tops on my list of things to solve b-4 I go any further with this boat. Maybe I didnt have it set rite? Even so , I thought it would pop off with the button as long as the pump was loaded with pressure ? No one in my area is familiar with popoff valves so I'm kinda on my own . Wouldnt mind a walk thru on exactly how it's "suppose" to work . I need all the help I can get with this thing. I spent all of last year getting use to this boat . Went to Louisiana a couple times & ran in some 1/8 mile drags to work on some seat time. Made Lots of passes & had no shut down issues. If I ran 660ft , I just took at least another 660ft to shut it down. The further the distance ,the higher the mph, the scarier it gets. I want to get the popoff valve working like I want so I can hit it b-4 backing out of the gas at the end of a run. My goal is to get enough seat time running at 1000' so I can run it at SMOKIN IN THE COVE in 2009. Thanks Rick Moore

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    It's a simple system.

    You have a box that is in line to the pop off from the steering wheel. In this box there is a relay that will send the 12v to the valve.

    Inside the valve there is a solenoid that will magnetize and lift a large metal "pin" (you should take the cap off the pop off and pull the large piston out, disassembling it ... take the aluminum cap off and look inside, you'll see what I'm talking about). Once the solenoid has lifted the large "pin" it will allow the 3 set pins to slide in (you will see little jam nuts on the outside of the pop off, those adjust the three set pins. Again, you need to take it apart to see what I am taking about).

    Once the set pins have nothing behind them (because the large pin has been lifted by the solenoid), they slide into the pop off piston and allow it to slide up. The piston goes up due to the pressure in the pump's intake.

    Again, take it apart ... you won't break anything, just don't loose the 3 small pins.

    Someone might have adjusted the jam nuts in too far to keep it from deploying.

    You should check and see if the button on the dash is giving you 12v at the solenoid. Also, use Torco MPZ spray lube inside the pop off to assist in lubrication.

    If you have any questions, feel free to ask. But I suggest taking it apart first.

    Good Luck.

    Brian

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    Busby , will do , thanks. I remember Penberthy showing me how to pull the whole piston up manually with the special lil wrench that came with it, back when I bought the boat. I tried doing that yesterday and couldnt even pull it up by hand. I'll try taking it apart & do some investigating.

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    Quote Originally Posted by cpjet View Post
    Busby , will do , thanks. I remember Penberthy showing me how to pull the whole piston up manually with the special lil wrench that came with it, back when I bought the boat. I tried doing that yesterday and couldnt even pull it up by hand. I'll try taking it apart & do some investigating.
    Hey Rick, Can you hear anything when you press the button??

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    Be rite back.......

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    Yep , there's a click at the black box & the little red lite lites on.

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    Senior Member cheyenne580's Avatar
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    I have an idea.Why not call the maker {Dan Nelson}623-780-1909.Instead of guessing and slamming the product.Just a thought.


    Jim S

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    Not for 1 second did I slam this product what so ever. The problem is not with the product it's with the user (me) not fully understanding how it works . I'm trying to learn here , that's it. Also I did call Dan this morning & I'm sure I'll here back from him soon. I know he's busy.

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    Quote Originally Posted by cpjet View Post
    Not for 1 second did I slam this product what so ever. The problem is not with the product it's with the user (me) not fully understanding how it works . I'm trying to learn here , that's it. Also I did call Dan this morning & I'm sure I'll here back from him soon. I know he's busy.
    Rick push and hold down the button have somebody pulling up with the tool i gave you.If you havent used it its just stuck and needs to be lubed! Gunna be hard to pull up but i bet it will!!

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    I would have no problem evaluating the unit for you and upgrading if possible.

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    Quote Originally Posted by cheyenne580 View Post
    I have an idea.Why not call the maker {Dan Nelson}623-780-1909.Instead of guessing and slamming the product.Just a thought.


    Jim S
    Jim, no one (at least I'm not) guessing or slamming Dan's valve.

    It's no secret how it works. I've spoke to Dan a lot about his valve when the one that Jerry Hicks had belonged to my ex Father-in-Law (Ron Fuentes). It went thru about 3 delrin pistons before Ron traded it into Jack @ MPD for a quikdata.

    After Jerry got it from Jack, they had to do more modifications before going another route. The original design he used from a Melluer valve (sp?), and it still needed to be re-engineered IMO.

    So no guessing from me about how it worked. And I'm not slamming, just trying to help.

    Brian

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    Quote Originally Posted by 1320h2o View Post
    Rick push and hold down the button have somebody pulling up with the tool i gave you.If you havent used it its just stuck and needs to be lubed! Gunna be hard to pull up but i bet it will!!
    Steve , I'll give it a try in the morning , thanks. Missed you at "Smokin In The Cove". We went & hung out all weekend & had a blast. Saw & spoke with Tom Bandy & Jerry Hicks & even MR. MPD himself. Jerry & Tom both really have there shit together. Jerry pocketed about 1300$ Saturday for #1 qualifier in 6 second class.

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