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Thread: Dual Intake Manifold Thoughts

  1. #21
    Super Moderator Corky's Avatar
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    Re: Dual Intake Manifold Thoughts

    Looks good Bart...With the carbs sitting upright like that it reminds me of the corvair engines from the 60s...Those were a popular choice around here for airboating back in the day but parts availability have dried up and so have most users for this area...
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    Aluminum .120 14' X 76" hull
    Teledyne 4a084-4 engine
    Circle S 1.69:1 reduction
    67" Whirlwind "Razor X" prop



  2. #22
    Junior Member Bart's Avatar
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    Re: Dual Intake Manifold Thoughts

    now I have some different options to choose from, as time permits.
    just need to purchase some carbs.

    option 1, dual mukini carbs,

    option 2 take the 90 degree elbows off and install dual Empi 34 pict carbs

    option 3 a weber 32/36 carb.

    option 4 a singe mukini w/center intake manifold

    option 5 single Empi 34 pict carb w/center intake manifold

    a couple of things that we found out as the intakes were tigged up.
    with the voltage at normal there was just to much splatter, and the impurities in these gas soaked old intakes, well it was just looking really ugly to say the least. we ended up turning the voltage to as low as it would go. instead of sounding like sizzling of frying bacon, it sounded like put... put... put... BUT the welds looked 100 percent better.
    we even soaked all the pieces in acetone over night, to attempt to leach out all the old gas and impurities out. you can see the ugly spatter on the one side, where it was tacked. when tigged at the normal voltage. and the nice looking side was tigged at the lowest setting. needless to say, i am glad we figured that out on the first weld.

    I am having second thoughts with the Mukini carbs. after reading the thread http://miniairboatassoc.com/forum/sh...prepping-4A084
    where the 084 fuel pump puts out too much pressure, for the floats in the mukini carbs can't shut off the fuel when it needs to. never thought that the 3 psi the fuel pump puts out, would be to much. (could buy a fuel pressure reducer) but at the moment, i think not.

    on the intake fabed up for the 32/36 carb, i left the front of the original intake on, so i could incorporate mounting tab to help hold up the extra weight of a larger carb. also made a plug that fits in the nose, to cut down on any turbulence. the intake is tapered, so the plug stops right where it needs to. and if i decide to install a vacuum gauge, i will drill a couple of small holes in it.

    we also put some more aluminum on the bottom of the center webbing, my thoughts are, so i can grind/sand out a nice profile between the front and back ports, and not have to worry about punching through the bottom.

    I have made up some adapter plates so i can orientate the Empi carbs to which ever direction is needed.

    so i did purchase an refurbished holley #6520 carb 32/36 on ebay, (34.00 plus shipping) what could go wrong. its not worth paying for it to be shipped back. seen some electrical wires coming out of it. thought it was an electric shut off, nope it wasn't, it was an electric metering valve. just doesn't look like it will work. so now i am looking at the Weber 32/36 carbs with no electric metering valves or electric fuel shut off valves. for the jetting, they have a kit for suzuki 1.3 liter motor, which could give me a starting point.

    well this has been a fun and learning experience, just reading up about these different carburetors, and how they fit and work, it has been well worth the time and effort spent.

    one more thing I am looking at is some new intake hose couplings. the original couplers are looking not so good, after taking them on and off so much. on ebay
    http://www.ebay.com/itm/391121760028...%3AMEBIDX%3AIT
    this is for some 1-3/8 blue 4-ply silicone hose tube coupler for turbo intakes,
    it states that it is not compatible with fuel or oil. but it is made to be used on turbo intakes and radiator hoses. to me i am thinking it could work. just don't want it to disintegrate and leach silicone and fresh air into the cylinders. so if anyone has any thoughts on this, let me know.
    thanks

    for getting into the center of the manifold, I have been using a bur bit extension. http://www.carbidebur.com/misc/airtools.htm
    you want to be careful with these, the reduced shank that fits into the die grinder, will bend/brake if it gets caught up on something. or it is out of balance.
    but it sure makes reaching some of the areas, very simple.
    used to use the Irwin 6" bit extension, part # 88702, but you will need to drill out the inside, so it will fit the 1/4" shank.
    just always need to be careful when operating these extensions at a higher speed, or they can take you for a ride.
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    Last edited by Bart; 01-10-2017 at 02:32 PM.

  3. #23
    Junior Member Bart's Avatar
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    Re: Dual Intake Manifold Thoughts

    edited some of the pictures. so now they are not in the order that I thought they were.
    did a little cleaning up on the inside of the intakes. with having the put a couple of weld passes on the bottom of the intake, i felt more comfortable in cleaning up the webbing a lot more. the first 2 pictures, is how much i felt comfortable in removing before i welded the passed on the bottom. Looking at the second picture, even though it is upside down. I never really realized how much webbing that was left between the front and back ports.

    The next couple show how much more, I was able to clean the center webbing out of the way.
    still have a little work to do on the bottom, to smooth it out.
    but you can see on these pictures. where i have gotten into the weld material, that was added to the bottom of the intake joint. starting to see some of the porosity.
    maybe i am going overboard, on cleaning up the extra casting, but most of the abrupt edges have been removed, just need to smooth out the center a little more.
    just never really liked how the casting left such a division between cylinders 1 & 2, and 3 & 4.
    ended up putting in a couple of pictures of the cast webbing that has not been touched. that came straight out of a box.
    when i was sanding it out with a die grinder, i stuck a vacuum hose in one port, put a paper towel in the openings of other ports. it was amazing on how much i didn't have to clean up when done.
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    Last edited by Bart; 01-10-2017 at 02:10 PM.

  4. #24

    Re: Dual Intake Manifold Thoughts

    That's some marvelous work !!!

    Did you use a metric crescent wrench or a left handed hammer ?

    Sorry that's about I ever work with

  5. #25
    Junior Member Bart's Avatar
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    Re: Dual Intake Manifold Thoughts

    well the wind finally slowed down enough to pull out the welder and try it out for the first aluminum mig weld. with my new welder. and it turned out real nice.
    so Bobby, got me thinking and realized that i needed to shorten the height of the progressive carb adapter. with the flange that was on it. it just didn't look right after seeing what Bobby did with his.
    so i cut out the flanges, held it together with some clamps, centered and put the top deck in the same plane as the existing intake throat. it ended up being 1-3/8" height. which is alot better than the 2-1/2" that is was before.
    once it was in a position that i liked, I tacked it multiple places so it would not shift as it was welded. after welding the inside and cleaning it up. there is just a little porosity, i may borrow my friends tig welder. and fill it in.
    i am thinking this should work. the only concern is that I think Bobby came across an important tidbit. that has plagued many, that have been modifying their intakes, these motors do not like large cavities behind the carb. and on this one i may have made it to large just by cleaning it up like i did. but time will tell. the other 4 carb intakes that I have, i haven't removed as much as i did on this one.
    hope that the pictures show a little & help explain what Bobby and I have opted to do.
    i have left the original tube on, and will fill it in with a plug. so there is no dead air space in the intake.
    the reason why is with the heaver carb. i want to use the factory mounting tab to attach it to the motor.
    one way or another the intake will need supported with this larger carb.
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    Last edited by Bart; 04-06-2018 at 02:44 AM.

  6. #26
    Junior Member Bart's Avatar
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    Re: Dual Intake Manifold Thoughts

    there was one little frustration that i had with my aluminum mig gun. i had put down a few beads and i was noticing that the snout coming off of the gun was coming loose. when it was assembled the locking nut on the inside was not put on to well, but it is back together and i am pretty happy with the results. i cant wait for an other month when i can split my boat hull and really have some fun. below is just the few passes that i made with it. i guess it is almost like riding a bike, once you learn. it comes back.
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  7. #27
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    Re: Dual Intake Manifold Thoughts

    i took a piece of angle and mounted it to the right front bolt on 4 bolt adapter and run it down to the engine and supportes the carb nicely. thats some nice work bart. i was planning to split caseys boat and make it wider also but after he had finished his work on it i decided not to. it gets on plane now a lot better than when i was using it with the heavy rigging i had on it. i may let you lead the was on the dual carb setup. looks like you got it almost figured out.
    Last edited by bgmcl60; 04-06-2018 at 06:41 PM.
    4a084
    Arrow belt drive
    marty bray 116 mini pro
    solex 32/36
    weber 32/36
    solex 34 pict 3
    weber 34 ich
    Razor x 3 blade

  8. #28
    Junior Member Bart's Avatar
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    Re: Dual Intake Manifold Thoughts

    i may end up cutting off the front also. just to free up some space. i will see what it looks like.
    i am getting the itch. to hear this motor. i am getting jealous every time you post a video or picture of your motor running.
    i may just have to fab up an stand to secure the motor, while i am waiting for my friend to finish up the cad drawing. i am wanting to here this motor run. and see if any of my ideas are going to pan out.

  9. #29
    Super Moderator Corky's Avatar
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    Re: Dual Intake Manifold Thoughts

    Nice work Bart...I found that adapter at a reasonable price on Ebay and I'll probably get it...Then use the link Bobby posted for the progressive carb so I'll have a complete set-up that's proven...I like having options...

    Aluminum .120 14' X 76" hull
    Teledyne 4a084-4 engine
    Circle S 1.69:1 reduction
    67" Whirlwind "Razor X" prop



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