I have a chance to buy a pair of vintage magnesium valve covers for my 392 hemi. The only thing I'm concerned about is the corner of one has a small crack on the corner, like it was dropped. I think if I try to straighten it it will break off. Can this be repaired? Any help or advice would be appreciated. Thanks! Tim here's the crack:
Marine Tex on the inside? Don't know what else to recommend. You certainly don't want to get near it with a torch.
Actually, magnesium is quite easy to weld. A block or bar is quite difficult to ignite even intentionally- its only small shavings and dust that's easy, due to the surface area. I've TIGged mag several times, with good results. Mag rod is hard to come by- you'll have to special order it- but the actual welding is really no more difficult than doing aluminum. On your covers, you'll want to just snap or grind that broken tab off, then build it back up with weld. That piece is small enough there could be some risk of ignition. Strongly recommended you weld outside, or on a solid steel table with lots of clearance to anything even remotely flammable- including the ceiling. A couple of big buckets of dry sand as a last-ditch extinguisher can't hurt, or a real Class D extinguisher if you can find one. And of course, if you do grind, do it well away from where you'll be welding. Doc.
Potentially very cool covers! I don't know much about magnesium, or welding it, but Doc's reply sounds very logical to me.
yeah just make sure you have a lot of purging. get a dual feed line from your regulator and then put a purge block under it and then use a 3/4 or 1 inch tig shield on your torch. also make sure you dont pull the end of the rod out of the gas while you are welding it.
Before you fire up the TIG welder bolt a steel chain to your part. If it does light up, you can quickly drag it out of your shop. Welding old cast Mag is kind like welding old cast aluminum - sometime's its sweet & somtime's its poop - depends on the alloy originally used.
Agree with fang.used jb weld on mine which is alittle bigger crack and it worked fine,and is hard to see unless toure looking for it
I had a main web on an aftermarket VW magnesium case welded up with good result. found the crack on a tear down from a dropped valve on a sat. night race trying to get it together for a sunday race. called up a guy I raced with who welded up magnesium quick changes and he welded it up for me that night. scared the crap out of me when he put a torch on it to pre/post heat it but it came out great and I made the race the next day.
Heres an idea If your going to polish them ,Solder ,Its just an idea .I dont know if you can get clean enough I personally like the JB weld idea .Magnesium burns very weird .I use to work at a scrap yard and Ive torched mag before .I know it can be dangerous and water fuels the fire.Alumna weld might be another possibility,
Those covers are very cool. I'd buy 'em just to hang on the wall the. It looks like you could run them as is, maybe the JB would look good unless you polish them. Follow Docs advice if you want to fix them right. Here's another tech article by Brian Bass on welding magnesium, good info there. http://www.jalopyjournal.com/forum/showthread.php?t=184445
Doc has a handle on it. Magnesium is very volitile but it takes a lot to get it started. You can tig weld it no problem. Well No problem is a relative term it does take a bit of talent.
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