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Thread: I broke my carb....sad day in the garage.

  1. #1
    Registered User dawg7's Avatar
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    Default I broke my carb....sad day in the garage.

    I haven’t started the car in a few weeks (due to traveling) and I wanted to hear the car purr. But the #3 carb was gushing out gas…..not dripping. I mean shoot, just two weeks I was hauling butt up and down the highway! So I am thinking the float has a hole in it or the needle seat is jacked somehow. I take off the carb top and start to take off the float. I didn't have the punch lined up right and pushed too hard on the float pin. I broke the pin support on the carb top. Anyone have a 40DCOE-18 carb top? I don't want to get too discouraged but these damn carbs! Driving me to drink!...

    74 260Z RLS30-016515 12/73
    3.1 Stroker; Weber 40DCOE; 5 sp
    225/50/15 BFG gForce on Konig Rewinds

  2. #2
    Rust Free'ish zKars's Avatar
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    Never fear, it can be fixed! where on the support bar did it break? Right at the split where the pin fits, or down lower?

    Order an HTS 2000 welding/brazing rod (google for a supplier like HTS-2000, Low temperature Brazing Rods for thin alloys, cast aluminum, zinc, magnesium and nonferrous metals. looks like they are in Houston) and try to braze it back on. If you weren't so dang far away.... Hmmmm, listen, just mail me your busted one, I'll mail you a good one, and I'll fix yours and keep it. Have to see a picture first I guess to judge how hard a fix this is. drop me a note to z240@shaw.ca and we do it from there.
    Last edited by zKars; 03-14-2014 at 11:44 AM.
    -----------------------------------------
    Jim
    73 240Z HLS30 149331
    69 510 PL510 77603

    www.zKars.com
    www.calgaryzclub.ca
    Reference materials
    www.xenonS30.com

  3. #3
    Registered User madkaw's Avatar
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    JB Weld it. It doesn't have to be strong, but the JB Weld will stick and hold up to fuel and you form it, drill it-whatever
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

  4. #4
    Registered User madkaw's Avatar
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    Ran into the flooding issue on my Mikuni's and it was the needle/seat was not tight and caused fuel to go around the threads instead of being metered. Check for tightness--after you fix the float
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

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    Registered User dawg7's Avatar
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    I have used jb weld many times but never in or around fuel. I do like the idea of brazing it back together. Here is a pic of the break; right there next to my favorite liquid.....




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    74 260Z RLS30-016515 12/73
    3.1 Stroker; Weber 40DCOE; 5 sp
    225/50/15 BFG gForce on Konig Rewinds

  6. #6
    Registered User madkaw's Avatar
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    I wouldn't hesistate to fix that with JB weld. You can reconstruct the shape easily and leave a hole. Believe it or not I did the same thing on a SU carb. In a pinch I hung the float with one side of the pin and some saftey wire. It actually lasted a long time and I broke the whole pin tower off.
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

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    Registered User Oiluj's Avatar
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    If you have access to a machine shop, you can mill the bad section off and "pin" a replacement section on.
    Would not be difficult to make a replacement tower.
    Last edited by Oiluj; 03-15-2014 at 05:28 PM.
    Julio
    1972 240Z (in-progress, 95% complete)
    CZC# 15388

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    Registered User dawg7's Avatar
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    I am going to buy a brazing setup and give that a shot. I have a car builder friend that is going to supervise....He does good work so I think it will be a success. Thanks for the advice and the offer. It is greatly appreciated.

    74 260Z RLS30-016515 12/73
    3.1 Stroker; Weber 40DCOE; 5 sp
    225/50/15 BFG gForce on Konig Rewinds

  9. #9
    Registered User madkaw's Avatar
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    Just my opinion, but to try out a "brazing set-up" to fix that might not be the best choice- IMHO.
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

  10. #10
    Registered User dawg7's Avatar
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    I did read a lot about how well JB weld holds up on gas tank repairs. And I have used JB weld on intakes in the past. And I have some in the shop. And it would be a repair I can do on my own.

    74 260Z RLS30-016515 12/73
    3.1 Stroker; Weber 40DCOE; 5 sp
    225/50/15 BFG gForce on Konig Rewinds

  11. #11
    Registered User madkaw's Avatar
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    It would be a good valid repair and a very minor repair. You can drill JB as you probably already know. I will probably use JB to install my fuel injector bungs on my intake. You be fixed up in a day too!
    I would be afraid of ruining that cover with too much heat. Stuff like that is kind of hard to come by.
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

  12. #12
    Rust Free'ish zKars's Avatar
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    I'll try to describe my experience in using the HTS2000 rods to help this go smoothly for you

    Think of what you are doing like this. That post, when it broke, left you with two rough surfaces on each side of the part where the post fractured. Your objective is put "glue" on both of those rough surfaces that you are re-joining, then get the "glue" covered faces to stick to each other. You are NOT, trying to surround the two broken parts with a glob of this molten rod to hold them together the way you might wrap a blob of JB weld on there.

    So rule one. The metal has to get hot enough to melt the rod. The rod must not be melted via flame heat. Heat the metal with a flame, remove the flame, then touch the rod to the metal, which must melt the rod. HTS2000 melts 500F cooler than aluminum itself melts, BUT with such a small part, you have to be very careful with the heat. Apply heat for 10 seconds, try touch the rod to the part. No melt?, apply flame for 20 seconds, try again. Continue adding time until the rod just melts so you can work with it, and you can keep the melt going with on-off flame application. The rod turns shiny when it melts, goes dull when it solidifies.

    Rule two. to get the metal face to "wet itself" with the molten rod you have to have a perfectly clean surface, which you get with first acetone soak to degrease, and second, with a fine stainless steel brush to clean the metal of oxidation. To get the metal to "wet" into the pores of the aluminum, you have to RUB the molten rod into the surface of the metal. Just putting a blob on there won't work, you have to work it in. The HTS rod instructions speak of using that SS brush to rub it in. This works, but for tiny parts, I'm not sure. You can use the mechanical action of rubbing the rod onto the surface as its melting to work it in too. If you get it right, you will have a shiny surface coated wwith the molten rod, with the same roughness it had to start with, ie you have a pretty thin coat on there.

    Once you get BOTH side of the break surface coated, you can assemble the parts, clamped together, which won't fit real tight because of the excess now coating the mating surfaces, but get it close. too Much rod on the surfaces makes alignment tough at this point. Then heat it up to the melt point again. When both side melt, the parts will magically mate together perfectly squeezing out any excess. Remove heat immediately. Let it cool naturally, no water bath!

    Now another approach may be to scrap that little part of the post that broke off and REPLACE it with a molten mass of HTS2000 rod, cool it and then file/dremel/drill it back into shape. You would have to build a thin sheet metal (steel or tin can) dam around the part (HTS won't stick to ferrous metals) to then fill with the molten rod. You would have to begin by creating a wetted surface on the part first as described above, then add enough rod volume to build it up beyond the size of the missing piece. Again, let it cool naturally.

    I've repaired broken bolt hole tabs on heads and front covers using this techique. ie don't "glue" the busted off part back on, build up material and machine up a new tab and hole. The cold rod material is stronger than the base aluminum.

    Good luck with your fix attempt. Maybe practice on same scrap Aluminum pieces about the size of the parts your working with to get a feel for heat and wetting. Have fun
    Last edited by zKars; 03-17-2014 at 12:52 PM.
    -----------------------------------------
    Jim
    73 240Z HLS30 149331
    69 510 PL510 77603

    www.zKars.com
    www.calgaryzclub.ca
    Reference materials
    www.xenonS30.com

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