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  1. #1
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    Jul 2002
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    Epoxy for Fuel Injection Bungs (from old site)

    Tireman71
    Registered User
    Posts: 67
    (12/30/03 4:48 am)
    Reply Epoxy for Fuel Injector Bungs
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    I am planning to epoxy-in some fuel injector bungs in a manifold I am working on. I was planning to use JB weld. Does anyone have experience or other recommendations?

    Thanks.

    Motornoggin1
    Registered User
    Posts: 143
    (12/30/03 10:05 pm)
    Reply Re: Epoxy for Fuel Injector Bungs
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    I have not epoxied fuel injector bungs in an intake, so I don't have that specific experience. I can only tell you of other experiences I've had. JB Weld is good for some things, it might work for the injector bungs, but I'm not sure I would trust it. If you do use it, use the regular and not the quick curing. Another product I've used (but can't tell you where to get it) is called Coretronix. It is a super strong aluminized epoxy that can withstand over 1200 deg. and is extremely stable. It is used for aerospace applications and is expensive (but you aren't going to use tons of it). Basically, it is designed to be used for this type of thing as it is heat stable, machinable, strong and chemical resistant. You might also look into a product from MSD. They have epoxy type injector bungs and might offer epoxy for this application.

    Tireman71
    Registered User
    Posts: 68
    (12/31/03 5:27 am)
    Reply Re: Epoxy for Fuel Injector Bungs
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    Thanks, I'll try to find this Coretronix stuff. I am using the MSD injector bungs. I did not see where they offered the epoxy, though.

    parsonsj
    Registered User
    Posts: 1404
    (12/31/03 6:48 am)
    Reply Re: Epoxy for Fuel Injector Bungs
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    Is there a reason you're not welding the bungs into place? I can't say I've ever seen epoxy used for this purpose...though it may work well. Are the metals dissimilar or something?

    John Parsons


    MarkM68
    Registered User
    Posts: 1134
    (12/31/03 6:56 am)
    Reply
    Re: Epoxy for Fuel Injector Bungs
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    Gas will eat JB Weld. Not that there would be alot of gas in this area, but just to let you know.

    I bet you could find someone to weld them in pretty cheap. If you had everything set up.
    My Pro-Touring 68 camaro, 468, 700r-4
    http://home.earthlink.net/~mutert23/

    Tireman71
    Registered User
    Posts: 69
    (12/31/03 8:54 am)
    Reply Re: Epoxy for Fuel Injector Bungs
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    I was wanting to epoxy them to avoid distorting the manifold. It is an old Hilborn manifold and the bungs are very close to the throttle bores.

    I thought JB weld was impervious to gas???



    parsonsj
    Registered User
    Posts: 1405
    (12/31/03 9:57 am)
    Reply Re: Epoxy for Fuel Injector Bungs
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    OK. I hear ya about welding distortion. It is a real concern. I think JB Weld is impervious to gas too.

    jp


    SDMAN
    Registered User
    Posts: 42
    (12/31/03 10:29 am)
    Reply bungs
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    Why not consider threading the outside of the bung and drilling and tapping the manifold and just screwing the bung in. There are several gasket sealers you could use to seal the threads that wont break down from the exposure to gasoline.

    Tireman71
    Registered User
    Posts: 70
    (12/31/03 1:25 pm)
    Reply Re: bungs
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    SDMAN,

    I agree it would be more secure to thread them. In fact MSD makes threaded bungs. I couldn't do it, though, because I didn't have the equipment to do anything other than a standard hole saw size (3/4"). I have a small milling machine and I removed the head and made a frame to have it drill the holes through the ports at the correct angle and position. I had to use a hole saw with a guide bar because my milling head was not stiff enough for cutting those holes at that angle with a regular bit or 2 flute cutter. The hole saw was a little undersize, which was great because I was able then to turn down the bungs to have a nice tight fit. I've already cut the holes and fitted the pockets. I am only waiting to do the epoxy part once I choose the brand.

    Thanks...

    MarkM68
    Registered User
    Posts: 1141
    (1/1/04 5:34 pm)
    Reply
    Re: bungs
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    JB is not impervious to gas, from my experience.

    I was having problems with my carb loosing fuel going around tight corners. So an Edelbrock tech told me to use JB to block off a transfer tunnel in the rear of the carb with JB. So the fuel will not go from one bowl to the other. So I tried this. A few weeks later the car started to run like crap. Some of the JB had broke off and floated into the needle/seat. And the rest of it was really soft, so I removed the rest of it.

    I'd search for an Epoxy.
    My Pro-Touring 68 camaro, 468, 700r-4
    http://home.earthlink.net/~mutert23/

    Jim Nilsen
    Unregistered User
    (1/6/04 5:31 pm)
    Reply Lock-tite or Permatex
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    You might try a Lock-tite or Permatex dealer and look at the catalog of all of the things available. Some new products have come out that might be what you are looking for.

    There is also a company called " Fusor " that might have what you are looking for. Their products claim to chemically fuse the material together.


    Good luck, Jim Nilsen




    Jim Nilsen
    Unregistered User
    (1/6/04 5:39 pm)
    Reply and another...
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    I forgot to mention that "Devcon " products also have just about everything under the sun when it comes to epoxies and other adhesives and fillers that I know and trust to do the job.

    Jim Nilsen

    walapus
    Registered User
    Posts: 119
    (1/6/04 9:30 pm)
    Reply epoxies
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    There are two part gas tank repair epoxies, they would definitely be impervious to fuel, but I don't know how strong they would be. I would be nervous about epoxying them personally, if it breaks, you've got a whole list of bad things that could happen (loss of engine control, engine damage, fuel fire, etc). At least tack them in place in 2-3 spots and epoxy the rest, then you're not couting on the epoxy for strength. Pretty please.

    Tireman71
    Registered User
    Posts: 73
    (1/7/04 1:53 pm)
    Reply Re: epoxies
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    I've looked around and I can't get past the fact that I already have experience with JB weld on two intake manifolds and that gives me a warm-fuzzy. Also, the fuel rails will be fixed separately and the shape of the bungs will not allow them to fall in. Therefore, if the epoxy does crack, all that will happen is a vacuum leak, which should be noticeable. I'm sure I'll be checking regularly anyway.

    Thanks for the opinions...

    davidpozzi
    Moderator
    Posts: 980
    (1/12/04 9:56 pm)
    Reply
    Re: Epoxy for Fuel Injector Bungs
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    www.jbweld.net/uses.html
    67 RS Camaro, 69 Camaro vint racer, 65 Lola T-70 Can-Am vint racer.
    http://ourworld.compuserve.com/homepages/David_Pozzi/

    442olds
    Registered User
    Posts: 7
    (1/29/04 8:09 pm)
    Reply Re: Epoxy for Fuel Injector Bungs
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    I know this is a little off the beaten path, but I hav epoxied aluimnum injector bungs into a plastic (6-6 black nylon) runner using plasticweld. It worked quite well, you do need to make sure there are no leaks. But with JB weld it flows into the space before totaling curing so if you get a good amount on it you should be ok. Be sure to ruff up both surfaces with coarse grit sandpaper to get a good "bite".

    Here's a few pics of the plastic manifold I refered to which I built for a school project which uses a Honda CBR 600 F2/3 engine. When I went to Version 2 I switched to a two injector bung out of 6-6 white nylon.

    wwwcgi.umr.edu/cgi-bin/cgiwrap/formula/imagefolio2.2/imageFolio.cgi?action=view&link=Old_Cars/1999-19d&image=99_lower_intake_closeup.jpg&img=&tt=

    wwwcgi.umr.edu/cgi-bin/cgiwrap/formula/imagefolio2.2/imageFolio.cgi?action=view&link=Old_Cars/1999-19d&image=99_lower_intake.jpg&img=&tt=

    wwwcgi.umr.edu/cgi-bin/cgiwrap/formula/imagefolio2.2/imageFolio.cgi?action=view&link=Old_Cars/2000-19d&image=intake4.jpg&img=&tt=

    MarkM68
    Registered User
    Posts: 1548
    (6/23/04 9:22 am)
    Reply .
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    I was re-reading one of Smokey Yunicks books today and he was saying how when he was designing what became the Holley 4150 carb, he used Devcon epoxy's.

    So I did a search, and they're still around, .

    www.devcon.com/index.cfm


  2. #2
    Join Date
    Jun 2005
    Posts
    1
    I've seen JB weld used to fill cylinder head intake ports in motorcycle engines that run to 15,000 rpms on a daily basis. Surely none of the epoxy breaks up or else it would run into the engine and ruin the whole damn thing.

    I've used JB Weld to fill my intake ports around the intake valve seats and guides to smooth the port roof on my 4 cylinder 1.5L engine (in a tercel).. It runs daily to 7200rpm with no problems.

    If you don't believe me, look at this.

    Hmm... looks like JB weld on a TURBO car with BOOST.
    http://www.2gnt.com/www/corbin/8inj.html


  3. #3
    Join Date
    May 2000
    Posts
    4,152
    Country Flag: United States
    Wow, this is old. Tried JB Weld again on trying to repair a leaking fuel connections on a Weed eater. JB Weld broke down in about 2 days. If you're not convinced gas breaks down JB Weld, you haven't tried it, ;) .

  4. #4
    Join Date
    Oct 2005
    Location
    SoCal
    Posts
    489
    There are better automotive epoxies, some made specifically for port filling. But why go through all the hassle of drilling the manifold, setting the bungs properly, just to epoxy them? Spend an hour and tig them up, it's the proper way to do things.