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Thread: Help! Freshly rebuilt SU's leaking!

  1. #1
    Formerly known as Koalia Reverend's Avatar
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    Default Help! Freshly rebuilt SU's leaking!

    I just recently glass beaded my SU's plus sent all the hardware for zinc plating. I dont know can you call that a rebuild but anyhow. I tried to start the engine and first i did not notice anything until it made couple loud POP's. Then i went to see and saw it was squirting fuel everywhere. Mainly from that big bolt on float bowl.

    Does it have some sort of gasket or o-ring? cause i dont have any.. It leaks like crazy and i cannot start the engine.

    Also, what would be the best settings to start the car, as i have dismantled and rebuilt carbs. Jet up or down or something between? I have FSM and unisyn but first i need to get it running and warmed up...

    I really appreciate if you would help me fast, i need to get this baby running, wednesday is a big car show... :/Click image for larger version. 

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    I removed the bolt and checked if there was anything blocking the fuel, there was not. Also decent amount of gas in float bowl.
    -72 240Z "Goldie"

  2. #2
    Nova Scotia,Canada,Earth Blue's Avatar
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    yes there is a gasket on each side and a filter inside
    There is scarcely anything in the world that some man cannot make a little worse, and sell a little more cheaply.
    The person who buys on price alone is this man's lawful prey.


    John Ruskin (1819 - 1900)



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    AZ Z Fan duffman's Avatar
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    Sounds like the float is stuck or the fuel valve is stuck open.
    January 1970 240Z
    HLS3001399

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    Formerly known as Koalia Reverend's Avatar
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    I have filters on both carbs, but no gaskets. Rubber, paper or metal gasket? Im not sure about the valve, as float bowl was less than half full when i opened it. It would been squirting gas from float breather hose then, wich it did not.
    -72 240Z "Goldie"

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    Nova Scotia,Canada,Earth Blue's Avatar
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    Metal on one side, I believe paper on the other.

    Start with the jets at 2.5 complete turns down from their top most position.
    There is scarcely anything in the world that some man cannot make a little worse, and sell a little more cheaply.
    The person who buys on price alone is this man's lawful prey.


    John Ruskin (1819 - 1900)



    ZCars in Eastern Canada seaport ready for shipment to Europe

    http://ZSportCanada.com


  6. #6
    AZ Z Fan duffman's Avatar
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    I have seen mainly metal crush washers on both sides of bolt but other fuel resistant washers as well, most leaks are due to bolt not being tight enough with washers.
    January 1970 240Z
    HLS3001399

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    Registered User Stanley's Avatar
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    Mine have thin aluminum washers on both sides. Seems like rubber or something would be better.

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    Formerly known as Koalia Reverend's Avatar
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    I managed to find proper washers and it stopped the leak. Now its spewing out fuel from front of the carb so float settings must be crazy
    -72 240Z "Goldie"

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    n/m n/m
    Last edited by Darrel; 04-28-2013 at 03:57 AM.
    things will only bother you if you let them.

    82 280zxt 4 spd auto
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    short throw info

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    Registered User Travel'n Man's Avatar
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    When I was running SU's I always kept (and still have some) a few extra float bowl gaskets - once used, those things curl up like a pringle potato chip - anyway, did you replace or reuse that gasket?
    Life's a journey; enjoy the ride!

    Mitchell
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    1972 Datsun 240z
    HLS30-75040


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    Take the float bowl lid off and remove the needle and seat from the underneath side of the lid. Take it apart and flush with carb cleaner. You may have foreign material stuck in there holding it/them open. You may also want to check fuel pressure. More than about 3 1/2# of pressure can overpower the N&S holding them open.

    Another thing to check while the lids are off is to A. make sure the floats are moving up and down freely and B. while blowing lightly into the fuel inlet tube, while moving the float toward the lid, you can feel them (the N&S) shut off.
    Bruce Palmer
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  12. #12
    Formerly known as Koalia Reverend's Avatar
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    Floats/needles seem to work okay, i begin to question my timing advance. As it POPS and spews out smoke occasionally, but no bueno on start. I have DIY electronic dizzy (made by one local dizzy wizard) and it has this little red lamp that lits when engine is at TDC. Grooves on pulley match the lamp.

    EDIT: Now it does not even tr to start anymore. 12.2 volts on battery and it does not start... I wonder did i broke starter solenoid I did not "overstarted" as far as i know, only like 5 second periods, then pause, then again. Also the weirdest thing happened, i attached charger cables to battery and it almost fried the wires..!! What the heck is going on here..
    -72 240Z "Goldie"

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    Formerly known as Koalia Reverend's Avatar
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    Well as it seems, i had a faulty battery charger. No luck on getting car started yet..
    -72 240Z "Goldie"

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    It's awesome bartsscooterservice's Avatar
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    2 washers on the big bolt, and a paper gasket on the float bowl, I used liquid gasket, works so far.
    HLS30 32581, 5/71 Matching numbers

    Jay Leno : You know one week after the Americans have walked on the moon, the Japanese introduced this sports car, and…if you’re a car guy pretty equal. I mean walking on the moon was pretty good, but how many times you’d gonna walk on the moon? But here was an affordable sports car that had real performance and looked like it cost a lot more than it did.

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    Formerly known as Koalia Reverend's Avatar
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    Found a reason for the popping and coughing... Engine is at TDC and dizzy should be pointing down to the left, to 1 cylinder. Instead its pointing upwards.

    Click image for larger version. 

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    So i guess im taking the oil pump off and try to put the shaft right way back, right?
    -72 240Z "Goldie"

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    Quick and dirty is to re-plug the spark plugs on the distributor by 180 degrees:

    instead of 153624

    go 624154

    you should be able to start it and run. Move the oil pump/distributor after you try this.


    NOTE: Backfiring in intake and exhaust when starting is usually a sign the plugs are in the wrong order.
    There is scarcely anything in the world that some man cannot make a little worse, and sell a little more cheaply.
    The person who buys on price alone is this man's lawful prey.


    John Ruskin (1819 - 1900)



    ZCars in Eastern Canada seaport ready for shipment to Europe

    http://ZSportCanada.com


  17. #17
    Formerly known as Koalia Reverend's Avatar
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    Yea, thanks Blue! I think removing oil pump aint too complicated so im going that way, i wonder how many teeths that its off..
    -72 240Z "Goldie"

  18. #18
    Nova Scotia,Canada,Earth Blue's Avatar
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    The trick is to get the engine at top dead center first.

    One you do this then do this:

    1. remove the distributor
    2. drop the pump and spindle shaft (move the sway bar)
    3. align the dots as per the FSM and push the pump and spindle into place
    4. check the alignment of the keyed tip where the distributor goes (11:30 reference with small side forward) Repeat 2-4 until it is correct.
    5. install the distrributor
    There is scarcely anything in the world that some man cannot make a little worse, and sell a little more cheaply.
    The person who buys on price alone is this man's lawful prey.


    John Ruskin (1819 - 1900)



    ZCars in Eastern Canada seaport ready for shipment to Europe

    http://ZSportCanada.com


  19. #19
    Formerly known as Koalia Reverend's Avatar
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    Done that, thanks for the hint. Now new major problem emerged, more of that in HELP ME section... *sigh*
    -72 240Z "Goldie"

  20. #20
    Formerly known as Koalia Reverend's Avatar
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    Got rid of all the previous problems. Now i have new one to solve I decieded to continue this old thread, so i wont flood the forums with my nonsense.

    2 days ago in traffic lights, i smelled a strong fuel smell and engine started to idle rough, luckily i was almost at my destination and parked car in a minute. Rear fuel bowl was flooding over! Very weird thing indeed as i have driven about 300 miles with somewhat properly tuned (colortune) carbs. I adjusted the float but effect was that last 3 cylinders only fire up when rpms go over 2.5 K. Plugs were dry as desert. We opened up both float bowls and noticed that in rear one, that little jet is lower than in front carb. I have spare set of carbs so i took one jet out of it, except it is internally different than the other. Both have numbers 1-7 but internals are a bit different. Despite that i put the "new" jet on place and it started as usual, it runs much better now but i cannot get it to idle below 1000 rpms. It stutters and runs on 3 or less cylinders. over that rpm range, it runs great. So i guess i'll redo the balancing and idle settings but could there be something other causing this too?
    -72 240Z "Goldie"

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