Aluminum intake manifold repair with Miller 175

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I just got a Miller 175 mig machine. The first thing I'll be doing with it is restoring a 1970 Corvette. The frame needs some repair and the steel reinforcement inside the body needs a lot of help. It really doesn't seem to be too big of a problem however there is one area that I need guidance with.At some point in this restoration I will need to repair a Turbo 400 transmission that has a cracked bell housing and a '68 big block Chevrolet intake manifold. The transmission is pretty much a "weld the crack closed" kinda deal but the manifold has me stumped. This is a cast aluminum spread bore manifold from a '68 390HP 427 Corvette motor. The outside of the manifold is in mint condition and I would like to keep it that way however there is a problem with the carburetor flange area. This area has two primary and two secondary bores and an exhaust gas crossover passage. The exhaust gas crossover is made up of two half inch vertical holes that extend down onto the heat stove under the manifold and a milled slot that connects them. This passage has major erosion. This erosion is so bad that I no longer have a gasket surface at one of the primary bores and at three other places the thickness of the aluminum is down to two or three millimeters before it breaks out to the outside of the manifold. I would like to try to prevent this.I plan to press aluminum plugs into the vertical passages, then fill in the entire crossover passage with my welder. My question is, is this possible? If so, how would you gentlemen go about doing it with a Miller 175?Sorry for the long post.Thank you.BigBlockkLater.....Last edited by BigBlockk; 03-15-2005 at 12:14 AM.
Reply:Hey Bigblock,  Welcome. As for doing the steel work on your vette I would say the MIG you have will do it.  However, as for fixing the crack on the bellhousing(alum)and the intake I would highly suggest you "prep" it as best you can. V-grove clean and clean again. As for the "plugs" you are going to make get them all set as well and bring your alum. to a good TIG weldor. What you explain really requires a TIG machine. Also you need to bake the manifold to extract all the oil impurities out of the casting. I do this on a modified grill and then put it in speedy dry or kitty litter. When the manifold is ready for welding, it should also be pre-heated a little as well.   I know welders and machinists don't like to farm out stuff but sometimes we just don't have to "tools" to accuratley complete the job. I had to do this a couple of times before I got my TIG machine. Even when I did get my TIG machine I had to bring an intake manifold to an old timer aircraft TIG weldor with my helmut in hand and watched him perform his TIG magic on the alum. Ever since I watched him I do all my alum. TIG welding now.      For what is will cost you to set your MIG up for alum. you probably will not even pay as much to have someone TIG it for you. Post pics of the intake and the bell housing.Sorry for the long post.T.J.www.tjsperformance.com
Reply:Thank you for the response TJS. This repair is mostly filling in an eroded channel and plugging a couple holes. I have been told that you can do this with the machine that I have. Respectfully Sir, I will find out because I am going to do it myself. I have been reading a lot about different transfer rates and believe I may start out practicing on the thicker parts of this manifold to see what does what. The car this manifold is going on now sits in 4 large peaces inside and outside my garage so I have plenty of time to practice.Again, thank you for the response.By the way, nice web page you got there.BigBlockkLater.....
Reply:Here's an image of what I'm trying to repair.  Sorry for the double-post, but the edit timer expired on my original post.BigBlockkLater..... Attached Images
Reply:You might want to check this product out.  It was mentioned in another thread and one of the guys responding used on an ongoing basis to fill in pits on aluminum bus bars or something.  He seemed really pleased with the product.On their web site (below) they've got some really neat fixes like reconstructing a mounting ear on a transmission case, repairing heads, etc.  Claimed to be really strong with none of the issues with boiling out impurities that you might run into with TIG.  I don't have any first hand experience with it but I'm gonna pick up some to try.  If you decide to try it let us know how it worked out.http://newtechnologyproducts.net/aluminum_repair.htmTinkerTinkerCentury 135GS, ThermalArc 250GTS
Reply:the aluminum brazing rod mentioned in the prevous post might work for the job you are trying to do. for the price of the spool gun and controler to convert to aluminum you could replace the manifold and probably the transmition, however if you do the work yourself keep us posted as to how it works out.  Also on the mainfold if the top passage is that erroded how are the pasages inside the manifold?Matt in AK
Reply:About 10 years ago I got a old car (66 Lincoln). It had some pitting in the manifold where the gasket goes so it was unable to get a good seal. I sent it out to be fixed and they used some type of brazing to fix/fill it. After I had to file down the braze material because they couldnt machine it flat. Anyways it worked well and I didnt have any problems after with it.
Reply:I just repaired a broken ear on an EFI lower manifold. I TIG'd it using a dynasty 200DX machine. I thought this was a welding site not a gimic site for alum. brazing rod for H-2000 whatever it is. Sorry I hate this info mercial stuff. Back to my intake repair. I had to machine a pocket then turn some round stock (6061) to fit in that pocket and TIG it in. It took a lot of amps and a higher freq. to get the 6061 stock to wet into the casting. Try that with H-2000 and get it to hold. I doubt it. Here are some links to the repair I just did.As for welding ypur intake with a MIG you should pre-heat the intake it cause it will take a lot of heat to fill that in and actually get it to meld and "stick". Here are some links:T.J.www.tjsperformance.com http://www.tjsperformance.com/images/tonymintake.jpg   ----- broken earhttp://www.tjsperformance.com/images/tonymintake3.jpg  ----- millingpockethttp://www.tjsperformance.com/images/tonymintake7.jpg  ----- turnedbushinghttp://www.tjsperformance.com/images/tonymintake8.jpg  ----- flycuttingintakehttp://www.tjsperformance.com/images/tonymintake14.jpg  ------drill andtapping
Reply:TJS,Your quite right. TIG is the way to go for him. I was just mentioning what they did to my manifold. Hell...I dont even remember what the manifold was made from but it wasnt light   I'm wondering after looking at your pictures, how do you weld/melt the bushing into place so that the backside is also fused to the part that is milled out? Or is there no way to do that?axehind
Reply:Originally Posted by axehindTJS,Your quite right. TIG is the way to go for him. I was just mentioning what they did to my manifold. Hell...I dont even remember what the manifold was made from but it wasnt light   I'm wondering after looking at your pictures, how do you weld/melt the bushing into place so that the backside is also fused to the part that is milled out? Or is there no way to do that?axehind
Reply:Ok. This has been a learning experience. I struck my first arc with my new Miller mig machine just before going to work this afternoon. This is my setup. A Miller 175 mig welder, 100% argon gas (didn't really pay attention to the flow rate), .035" aluminum wire, steel gun liner, 50 amps and the voltage is on the 8 whatever that is. With a total arc time of about 1.5 minutes all I cam say is WOW. I had no idea this thing would put down so much metal. I was going to take pictures of my progress but it went so fast I couldn't. Probably for the best because the beads are terrible.The first bead was almost the full length of the eroded trench pushing with terrible fusion and a lot of spatter. Sounded like bacon frying. The second pass was right next to the first. About half way through this bead the arc began to hum. The weld pool became very wide and began to remelt the side of the original bead. I then ran another bead in the trench before starting on the left side hole (see photo in post above). After striking a 2 second arc then letting it cool a half dozen times I almost have the hole closed up. I burned through in 2 places on the left side hole (something I really didn't want to do). Oh well.There were no stoppages at all in the time I used the machine this afternoon. This is the first time I have used this machine for anything. The only training I have had in welding is a week long stick welding class that my employer put on. I got to say, this machine is going to make me look a lot better than I really am.Things look promising.BigBlockkLater.....