Newbie with SS welding question

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Hi everyone,Brand new to the forum and need help with a question on welding.  I have a wire feed flux core welder that I just use to fix little things here and there.  I also have a custom turbo project I've been working on for a while and have finally got around to the exhaust.  I simply need to tack up the muffler and hangers and then take it to a guy I know that can tig it for me.  My question is can I tack it with my flux core wire fed welder?  The system and mufflers is all t304 SS.  I know tig is the way to do this but I have to tack it in place first to make sure it will fit correctly and all I have is my flux core wire fed welder.  I've researched and read several times people say "it will no longer be stainless" when you weld SS with a regular welder but not sure what that means or if tacking vs welding is ok?  I know that the weld will rust but is that what that statement means or is there some chemical property change or something to the. Whole piece of SS?  Is this just around the weld or the whole piece of SS?  Thanks for any help/clarification.Last edited by Cfiiman; 03-29-2015 at 05:57 PM.
Reply:If you use mild steel based flux core wire, the part that gets diluted with it might rust later, but it won't spread like cancer unless it gets coated with road salt and is constantly wet.  Get flux core stainless wire, if you're really worried about it. 1st on WeldingWeb to have a scrolling sig! HTP Invertig 400HTP Invertig 221HTP ProPulse 300HTP ProPulse 200 x2HTP ProPulse 220MTSHTP Inverarc 200TLP HTP Microcut 875SC
Reply:Get a 2 lb. spoolgun size ss wire and do your tacking with that to preserve the integrity of the base metal like Oscar said above. Chip out all of flux possible as it will wreck your tig weldor's day, and be prepared to pay a premium or even a tip to him because it is a PIA to weld over. I have had my share of fluxcore tacks and I retack and then grind out the customer's tacks. And charge accordingly. They are still happy campers though.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Flux core will leave a residue that will mess up the TIG.You need a welder that will use gas during tacking.
Reply:I just joined the site, as well.  This is nearly spot-on with my predicament.  I have a Hobart Mig w/ Gas that I am unable to use since it is in storage and I don't have access to 220V.  I was considering just buying a cheap 110V gasless Mig to do JUST tacking, so that I could have a pro tig the 409/304SS exhaust pieces.  I have SS Mig wire that was to be used w/a Gas Mig; but, the person that volunteered the use of his lift & welder has flaked for over a month.So, I am in a bind to get my exhaust DONE.  Cannot afford to bring my "Builders Kit" of bends to an exhaust shop for them to make.  I can afford to pay a local to tig it; but, I have to bring [four] sections TO him, he's not an automotive shop.  That requires temporary Tacking.  To minimize my [wasted] expense buying a cheapo 110V Mig [that I'll not use again], I gather that I COULD pay the expense of a 2lb spool of SS wire for the task of Tacking [?]   If I were to do that, how do I "clean" the welds as much as possible for the tigging ?  Or ... any other thoughts.  BTW, I am a NOVICE, Self-Taught welder, so please be kind ...Thanks for looking !