I'll be splitting a flathead six manifold soon. I have some nickle rod which has worked fine in the past with the stick welder. I've heard that some have success with normal wire in a MIG but that sounds iffy to me. But, I found a spool of er308L that I bought at a local farm store clearance bin. So, I was wondering what do you think of using that to add steel extensions and flanges to a cast manifold? Or should I just stick with the stick with Ni-rod? I could braze, but with the cost of acetylene, I won't! Maybe propane and O2 to preheat before welding.
I would try brazing,,,,,Acetylene isn’t that expensive . Assuming you already have the tanks and gauges that is . I recently purchased my own set,,,,it was pricey,,,,,,but afterwards,,I was so proud of my brazing abilities. Read up on it ,,,,,,it’s not very difficult,,,,,and the work holds up very well,,,,almost as good as new . Tommy
I held and worked the torch for my dad as a kid when he split the exhaust on his 235. I kept the heat where he wanted it and he arc welded it with “I think” certainium? rod. Regardless, if you weld with wire I’d think preheating is needed. Brazing is its own preheat. It’s not structural, just needs to take vibrations.
my experience is that the post heat is just as important as the pre-heat. my trick for bringing it down to temp slowly is to take a disposable pan (like for a turkey) fill it with kitty litter and put it in the overn @ 400°. Once you are done welding, immediately bury it in the kitty litter and then turn the over off. It'll slowly bring it down to temp and will prevent cracking.
Welding Cast Iron, it has to be CLEAN. Not "clean enough to eat your dinner off". Cleaner than that. Fresh, bare metal. No grinding for the final prep. Use carbide burrs. The binder in the grinding discs can contaminate the weld. Welding Cast Iron is VERY fussy work. If you are Brazing, clean off all the Carbon. Bronze doesn't stick to Carbon. Yes, preheat is a must. Not the sort of thing to do in a COLD garage. Could use a propane BBQ for pre and post heating.
The braze will work - for awhile, eventually it'll sorta rot, the one that was in my 65 dodge pu S6(I didn't do it) lasted 5+yrs of hard use. I've seen exhaust manifolds done w/reg cheap mig wire hold together n last, but you've got to get all the contamination out of the welding area - that's kinda hard. At least one I saw didn't have any pre-heat, just quick-glued w/the mig. Guy didn't care, so it held... ;D . Neither would be my 1st choice, but sometimes... . Marcus...
The biggest thing with welding cast is it needs to be free of oil and grease . Pre-heated more importantly cooled sloooooooooowwwwwwwwly . my guy uses nickel rod when welding cast but says the pre-heat and cool down is the most important . he wraps stuff in pink fibreglass insulation and in a metal box for a slow cool down
A good pre-heat method is a weed burner on a propane tank. Easy to dial it back for cool down. I have had good success with silicone bronze wire in the mig.
308L is a stainless filler......which is a good thing when welding cast arn (as they say in Alerbammer) Wipe down with acetone then torch that manifold real well. Wire brush off all the contaminates. Clean it with a carbide burr tool (NOT a grinding wheel) Get it good & hot (250-300 degrees) Using the 308 wire do your welding.... Try to keep the temp of the piece good & hot. When finished welding get the piece back up to good & hot or maybe a little more. Wrap the piece in several layers type of thermal cloth(glass cloth) to hold in the heat. Wave the torch over the wrapped piece so it will slooooooowly cool off. Should be good. The stainless filler rod is 'soupy-er' than mild steel rod and will penetrate the pores of the cast iron better. Slooooow cooling is very important. 6sally6
I welded the exhaust manifold flange on my 8n tractor with flux core. Had a section that was burned out from leaking so long, built it up and ground it down several times until it was level with the other ports flanges. With new gaskets it sealed right up. Nobody told me it would or wouldn’t work. I figured at worst I’d have to replace the manifold. May have been lucky, but it worked.
Cast iron is a pain in the butt to weld. I quit doing structural cast welding years ago when another shop set up to pretty much weld cast iron only. I figured if he wanted to do that stuff, I was OK with him doing it. His shop was opened about 6 years before he closed up and moved away. I did some non-structural welding on things like cast park bench legs and such. You weld cast by either hot weld, which is recommended, and has already been explained, or you can weld it by the "cold" welding method. Cold cast iron welding can be done with things that are not under a heavy load, or something that doesn't see cold/hot cycles, or something where people won't get hurt if it fails. Cold weld cast failures are usually the cast breaking along side of the weld bead, and are usually caused by getting the cast too hot and cooling too fast, or trying to bridge a gap. Cooling time that exceeds 5 minutes probably needs to be covered so the weld area cools even slower (I often throw an old welding glove over the weld area after I do the short bead, just because). Cast iron that got too hot and cooled too fast almost guarantees a failure. Like any form of welding, practice improves the welds. Cold welding is pretty much just like it sounds. Short welds (1/4" to 1/2" long) where you pause when the cast starts getting hot to the touch and wait until it cools off. As one might think, its a slow process. I've done it with the Nickle stick rod, with stainless (308) wire in my mig, and with regular wire in my mig. The cast has to be clean and smooth, and it doesn't work well if you have gaps to fill. You obviously don't want a very deep or a very wide groove to fill. A mig weld on cast actually flows out surprisingly well. With the Nickle rod, you put a short weld bead on the cast, not much longer then a 1/4" long. Then you stop, clean off the slag, peen the area with a chipping hammer, wire brush the area, and wait until you can touch the weld with your bare fingers. Then after its cold, you repeat the process for another 1/4" and repeat the process time after time, until the weld is complete. The more distance you have to weld, the longer it takes to cool off. If the cool off time starts to take longer then 5 minutes, you really are getting too hot and probably have to cover the weld area so it will cool down slower. The mig wire process is about the same, except the mig can cover slightly more area before the cast gets hot, and you don't have to chip the slag off. The differences between the stainless wire and the regular wire is the stainless probably blends with the cast better then the regular wire does. I do recommend you peen the area and wire brush it between welds. It also has to cool off to the touch before you weld more. The trick here is if the cast gets too hot, you need to stop and cover it so it will cool slowly. You could do a cold cast weld on an intake if the pieces fit up well and you want to take the time. I would probably weld an end cap on an intake in at least 4 weld and cool down cycles, then add another to make sure any voids are closed up.
The thing lots of people seem to miss is that all cast iron isn't the same. The original contents can vary very much meaning the original properties (including weldability) can vary wildly, some versions aren't weldable at all. Then you get changes of the metal depending on what it's been exposed to, and high temperatures tend to oxidize silicon and burn out the carbon, making what once was weldable unweldable - it doesn't melt, it just falls apart. On top of that many confuse cast iron with cast steel, where cast iron is rather difficult to weld properly and cast steel can weld much like mild steel. Brazing is generally good, but remember that a brazed joint begins to lose strength over a few hundred degrees (C), a high performance engine may give you heat related problems when it comes to having a brazed exhaust manifold holding together. Some days working with cast iron goes well, some days you may be better off cutting your losses and building a new manifold from steel instead.
Good to hear that some have used 308 for this. I've done a fair amount of cast welding, but always with Ni-rod from one maker or another. All worked well but are really expensive now and I have that spool of 308, little 2 lb one but I think it was like 4-5 bucks on the clearance table. Also have some Ni-rod left on the shelf so should be all set as soon as I round up some donor manifold to cut up for the flange portion.
High performance heat related problems are not going to be an issue. Flathead six from a 56 Plymouth with a two bbl carb, little head mill and duals. On the bright side, early Mopar cast pieces are high quality and most have welded fine for me in the past. The use of 308 is going to be new to me though. If it works well it should speed up the actual welding part since there will be no slag cleanup. I hear you on differences as I've worked on some cast steel tractor parts and they weld just like 'normal' steel while looking like cast iron. Just takes a lot of preheat to weld big chunks with a little MIG.
Freeze crack. Tig weld with ER70. 1/8 mild steel patch. Not a row of dimes but cast iron doesn't like to do that.
I pulled up these pages on welding cast iron in the book in the last photo. about 16 bucks on Amazon and a pretty decent guide for most home shop welding needs.
Just Welded these 200cci flanges to some exhaust pipe with my little hobart 140 and lincoln flux core 0.30 wire. Heat it just a bit and went to town.
That looks pretty good. Have you hit it with a hammer yet? Years ago, I did the same to a cheap cast iron vise. It looked pretty good, so I mounted the vise to use it. On the first good pull on the handle, it broke again, right along the edge of the bead. I hope your effort has better results than mine did.
Yes I did the ring test...rings like a bell... Now we're going to go through the heat/cold cycle..I split my exhaust manifold and now these on this engine...time will tell. After a bit of clean up.
What is your source for cast flanges? I'd like some 'cause the cheap, thin steel versions don't seal well.
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